Obesity and prostate cancer-specific mortality after radical prostatectomy: results from the Shared Equal Access Regional Cancer Hospital (SEARCH) database.

BACKGROUND: At the population level, obesity is associated with prostate cancer (PC) mortality. However, few studies analyzed the associations between obesity and long-term PC-specific outcomes after initial treatment. METHODS: We conducted a retrospective analysis of 4268 radical prostatectomy patients within the Shared Equal Access Regional Cancer Hospital (SEARCH) database. Cox models accounting for known risk factors were used to examine the associations between body mass index (BMI) and PC-specific mortality (PCSM; primary outcome). Secondary outcomes included biochemical recurrence (BCR) and castration-resistant PC (CRPC). BMI was used as a continuous and categorical variable (normal <25 kg/m2, overweight 25-29.9 kg/m2 and obese ⩾30 kg/m2). Median follow-up among all men who were alive at last follow-up was 6.8 years (interquartile range=3.5-11.0). During this time, 1384 men developed BCR, 117 developed CRPC and 84 died from PC. Hazard ratios were analyzed using competing-risks regression analysis accounting for non-PC death as a competing risk. RESULTS: On crude analysis, higher BMI was not associated with risk of PCSM (P=0.112), BCR (0.259) and CRPC (P=0.277). However, when BMI was categorized, overweight (hazard ratio (HR) 1.99, P=0.034) and obesity (HR 1.97, P=0.048) were significantly associated with PCSM. Obesity and overweight were not associated with BCR or CRPC (all P⩾0.189). On multivariable analysis adjusting for both clinical and pathological features, results were little changed in that obesity (HR=2.05, P=0.039) and overweight (HR=1.88, P=0.061) were associated with higher risk of PCSM, but not with BCR or CRPC (all P⩾0.114) with the exception that the association for overweight was no longer statistical significant. CONCLUSIONS: Overweight and obesity were associated with increased risk of PCSM after radical prostatectomy. If validated in larger studies with longer follow-up, obesity may be established as a potentially modifiable risk factor for PCSM.

Long-term oncological outcomes of apical positive surgical margins at radical prostatectomy in the Shared Equal Access Regional Cancer Hospital cohort.

BACKGROUND: Approximately 29-38% of all positive surgical margins (PSMs) at radical prostatectomy (RP) involve the apex. The prognostic significance of apical PSM remains unclear. We therefore compared the long-term oncologic outcomes of men with apical PSMs to those with negative PSMs, apical and other PSMs, and other PSMs at RP. METHODS: The SEARCH (Shared Equal Access Regional Cancer Hospital) database was used to identify 4031 men with prostate cancer (PCa) managed with RP with complete pathologic grade and stage data. Margin status was categorized as negative, apex only, or other positive. Multivariable Cox regression models adjusted for pathologic stage and grade were developed to test the relationship between margin status and biochemical recurrence (BCR), metastases and PCa death. RESULTS: In the final cohort, 34.3% had PSMs, whereas 65.7% had negative margins. Univariable analysis showed that compared with negative margins, apex-only PSM was associated with BCR (hazard ratio (HR): 1.4 [1.1-1.8]), but not metastases or PCa death, whereas apex and other PSMs were associated with BCR (HR: 3.3 [2.8-4]) and metastases (HR: 1.8 [1.02-3.1]) but not PCa death. Nonapical PSMs were associated with BCR (HR: 2.7 [2.4-3.1]), metastases (1.7 [1.2-2.5)] and PCa death (1.8 [1.05-3]). On multivariable analysis, apex-only, apex and other, and nonapical PSMs were associated with BCR but margin status was not associated with metastases or PCa death. CONCLUSIONS: In a large cohort of men undergoing RP, those with PSMs at the prostatic apex had lower BCR, metastases, or PCa death compared with those with PSMs at other locations. When adjusted for pathologic stage and grade, however, PSMs were associated with BCR but not long-term oncologic outcomes. These data confirm that men with apex-only PSMs may not be ideal candidates for adjuvant therapy after RP.

Do skeletal-related events predict overall survival in men with metastatic castration-resistant prostate cancer?

BACKGROUND: Skeletal-related events (SREs) including pathologic fracture, spinal cord compression, radiation to bone and surgery to bone, are common in men with bone metastatic castration-resistant prostate cancer (mCRPC). Men with mCRPC are at high risk of death. Whether SREs predict mortality is unclear. We tested the association between SREs and overall survival (OS) in a multiethnic cohort with bone mCRPC, controlling for key covariates unavailable in claims data such as bone pain, number of bone metastases and PSA doubling time (PSADT). METHODS: We collected data on 233 men diagnosed with nonmetastatic castration-resistant prostate cancer (CRPC) in 2000-2013 at two Veterans Affairs hospitals who later progressed to bone metastases. First occurrence of SRE and OS were collected from the medical records. Cox models were used to test the association between SRE and OS, treating SRE as a time-dependent variable. We adjusted for age, year, race, treatment center, biopsy Gleason, primary treatment to the prostate, PSA, PSADT, months from androgen deprivation therapy to CRPC, months from CRPC to metastasis and number of bone metastases at initial bone metastasis diagnosis. In a secondary analysis, we also adjusted for bone pain. RESULTS: During follow-up, 88 (38%) patients had an SRE and 198 (85%) died. After adjusting for risk factors, SRE was associated with increased mortality (hazard ratio (HR)=1.67; 95% confidence interval (CI) 1.22-2.30; P=0.001). When bone pain was added to the model, the association of SREs and OS was attenuated, but remained significant (HR=1.42; 95% CI 1.01-1.99; P=0.042). CONCLUSIONS: SREs are associated with increased mortality in men with bone mCRPC. Further studies on the impact of preventing SREs to increase survival are warranted.

A randomized, double-blind, placebo-controlled study of the effects of pomegranate extract on rising PSA levels in men following primary therapy for prostate cancer.

BACKGROUND: The primary objective of this study was to compare the effects of pomegranate juice on PSA doubling times (PSADT) in subjects with rising PSA levels after primary therapy for prostate cancer. METHODS: Double-blind, placebo-controlled multi-institutional study, evaluated the effects of pomegranate liquid extract on serum PSA levels. The primary end point of this study was change in serum PSADT. Additional secondary and exploratory objectives were to evaluate the safety of pomegranate juice and to determine the interaction of manganese superoxide dismutase (MnSOD) AA genotype and pomegranate treatment on PSADT. RESULTS: One-hundred eighty-three eligible subjects were randomly assigned to the active and placebo groups with a ratio of 2:1 (extract N=102; placebo N=64; juice N=17). The majority of adverse events were of moderate or mild grade. Median PSADT increased from 11.1 months at baseline to 15.6 months in the placebo group (P<0.001) compared with an increase from 12.9 months at baseline to 14.5 months in the extract group (P=0.13) and an increase from 12.7 at baseline to 20.3 in the juice group (P=0.004). However, none of these changes were statistically significant between the three groups (P>0.05). Placebo AA patients experienced a 1.8 month change in median PSADT from 10.9 months at baseline to 12.7 months (P=0.22), while extract patients experienced a 12 month change in median PSADT from 13.6 at baseline to 25.6 months (P=0.03). CONCLUSIONS: Compared with placebo, pomegranate extract did not significantly prolong PSADT in prostate cancer patients with rising PSA after primary therapy. A significant prolongation in PSADT was observed in both the treatment and placebo arms. Men with the MnSOD AA genotype may represent a group that is more sensitive to the antiproliferative effects of pomegranate on PSADT; however, this finding requires prospective hypothesis testing and validation.

Predicting bone scan positivity in non-metastatic castration-resistant prostate cancer.

BACKGROUND: To evaluate PSA levels and kinetic cutoffs to predict positive bone scans for men with non-metastatic castration-resistant prostate cancer (CRPC) from the Shared Equal Access Regional Cancer Hospital (SEARCH) cohort. METHODS: Retrospective analysis of 531 bone scans of 312 clinically CRPC patients with no known metastases at baseline treated with a variety of primary treatment types in the SEARCH database. The association of patients' demographics, pathological features, PSA levels and kinetics with risk of a positive scan was tested using generalized estimating equations. RESULTS: A total of 149 (28%) scans were positive. Positive scans were associated with younger age (odds ratio (OR)=0.98; P=0.014), higher Gleason scores (relative to Gleason 2-6, Gleason 3+4: OR=2.03, P=0.035; Gleason 4+3 and 8-10: OR=1.76, P=0.059), higher prescan PSA (OR=2.11; P<0.001), shorter prescan PSA doubling time (PSADT; OR=0.53; P<0.001), higher PSA velocity (OR=1.74; P<0.001) and more remote scan year (OR=0.92; P=0.004). Scan positivity was 6, 14, 29 and 57% for men with PSA<5, 5-14.9, 15-49.9 and ⩾ 50 ng ml(-1), respectively (P-trend <0.001). Men with PSADT ⩾ 15, 9-14.9, 3-8.9 and <3 months had a scan positivity of 11, 22, 34 and 47%, correspondingly (P-trend <0.001). Tables were constructed using PSA and PSADT to predict the likelihood of a positive bone scan. CONCLUSIONS: PSA levels and kinetics were associated with positive bone scans. We developed tables to predict the risk of positive bone scans by PSA and PSADT. Combining PSA levels and kinetics may help select patients with CRPC for bone scans.

Predicting bone scan positivity after biochemical recurrence following radical prostatectomy in both hormone-naive men and patients receiving androgen-deprivation therapy: results from the SEARCH database.

BACKGROUND: To evaluate the factors associated with positive bone scans after biochemical recurrence (BCR) following radical prostatectomy in both hormone-naive subjects and subjects after androgen-deprivation therapy (ADT). METHODS: Retrospective analysis of 380 bone scans of 301 hormone-naive subjects and 214 bone scans of 137 subjects after ADT following BCR from the Shared Equal Access Regional Cancer Hospital database. Generalized estimating equations and local regression plots were used to evaluate bone scan positivity by patients' demographics, pathological features, PSA levels and kinetics. RESULTS: Among hormone-naive subjects and subjects on ADT, bone scan positivity was seen in 24 (6%) and 65 (30%) subjects, respectively. In hormone-naive subjects, the higher prescan PSA, higher PSA velocity (PSAV) and shorter PSA doubling time (PSADT) were significantly associated with positive scans (P=0.008, P<0.001 and P<0.001, respectively). In subjects after ADT, the prescan PSA, PSAV and PSADT were significantly associated with positive scans (P=0.011, P<0.001 and P=0.002, respectively). Regression plots showed increased scan positivity with increasing PSA levels and shortening PSADT (all P<0.001) for both hormone-naive subjects and subjects after ADT. For a given PSA level and PSADT, subjects on ADT had higher bone scan positivity. CONCLUSIONS: In both hormone-naive subjects and subjects after ADT, more aggressive and advanced disease identified by higher PSA levels, higher PSAV and shorter PSADT were associated with higher bone scan positivity. For the same PSA level and PSADT, subjects after ADT had higher bone scan positivity than hormone-naive subjects. Therefore, PSA levels and kinetics may be used as selection criteria for bone scan in these patients.

Metformin does not affect risk of biochemical recurrence following radical prostatectomy: results from the SEARCH database.

BACKGROUND: While epidemiologic studies suggest that metformin use among diabetics may decrease prostate cancer (PC) incidence, the effect of metformin use on PC outcome is unclear. We investigated the association between pre-operative metformin use, dose and duration of use and biochemical recurrence (BCR) in PC patients with diabetes who underwent radical prostatectomy (RP). METHODS: We conducted a retrospective cohort analysis within the Shared Equal Access Regional Cancer Hospital (SEARCH) database of 371 PC patients with diabetes who underwent RP. Time to BCR between metformin users and non-users, and by metformin dose and duration of use was assessed using multivariable Cox proportional analysis adjusted for demographic, clinical and/or pathologic features. Time to castrate-resistant PC (CRPC), metastases and PC-specific mortality were explored as secondary outcomes using unadjusted analyses. RESULTS: Of 371 diabetic men, 156 (42%) were using metformin before RP. Metformin use was associated with more recent year of surgery (P<0.0001) but no clinical or pathologic characteristics. After adjustment for year of surgery, clinical and pathologic features, there were no associations between metformin use (hazard ratio (HR) 0.93; 95% confidence interval (CI) 0.61-1.41), high metformin dose (HR 0.96; 95% CI 0.57-1.61) or duration of use (HR 1.00; 95% CI 0.99-1.02) and time to BCR. A total of 14 patients (3.8%) developed CRPC, 10 (2.7%) distant metastases and 8 (2.2%) died from PC. Unadjusted analysis suggested that high metformin dose vs non-use was associated with increased risk of CRPC (HR 5.1; 95% CI 1.6-16.5), metastases (HR 4.8; 95% CI 1.2-18.5) and PC-specific mortality (HR 5.0; 95% CI 1.1-22.5). CONCLUSIONS: Metformin use, dose or duration of use was not associated with BCR in this cohort of diabetic PC patients treated with RP. The suggestion that higher metformin dose was associated with increased risk of CRPC, metastases and PC-specific mortality merits testing in large prospective studies with longer follow-up.

Fish oil slows prostate cancer xenograft growth relative to other dietary fats and is associated with decreased mitochondrial and insulin pathway gene expression.

BACKGROUND: Previous mouse studies suggest that decreasing dietary fat content can slow prostate cancer (PCa) growth. To our knowledge, no study has yet compared the effect of multiple different fats on PCa progression. We sought to systematically compare the effect of fish oil, olive oil, corn oil and animal fat on PCa progression. METHODS: A total of 96 male severe combined immunodeficient mice were injected with LAPC-4 human PCa cells. Two weeks following injection, mice were randomized to a Western diet based on fish oil, olive oil, corn oil or animal fat (35% kilocalories from fat). Animals were euthanized when tumor volumes reached 1000 mm(3). Serum was collected at death and assayed for PSA, insulin, insulin-like growth factor-1 (IGF-1), IGF-1-binding protein-3 and prostaglandin E-2 (PGE-2) levels. Tumors were also assayed for PGE-2 and cyclooxygenase-2 levels, and global gene expression was analyzed using Affymetrix microarrays. RESULTS: Mice weights and tumor volumes were equivalent across groups at randomization. Overall, fish oil consumption was associated with improved survival relative to other dietary groups (P=0.014). On gene expression analyses, the fish oil group had decreased signal in pathways related to mitochondrial physiology and insulin synthesis/secretion. CONCLUSIONS: In this xenograft model, we found that consuming a diet in which fish oil was the only fat source slowed tumor growth and improved survival compared with that in mice consuming diets composed of olive oil, corn oil or animal fat. Although prior studies showed that the amount of fat is important for PCa growth, this study suggests that the type of dietary fat consumed may also be important.

Preoperative weight change and risk of adverse outcome following radical prostatectomy: results from the Shared Equal Access Regional Cancer Hospital database.

BACKGROUND: We examined the relationship between weight change in the year before radical prostatectomy (RP) and biochemical recurrence (BCR) and adverse pathology. METHODS: We abstracted data from 359 men undergoing RP in the SEARCH (Shared Equal Access Regional Cancer Hospital) database between 2001-2007. Logistic regression and Cox proportional hazards models were used to test the association between weight change in the year before surgery and adverse pathology and BCR, respectively. RESULTS: In all, 152 (42%) men gained weight, 193 (54%) lost weight and 14 (4%) had the same weight. Among weight gainers, median gain was 2.4 kg and among weight losers, median loss was 2.7 kg. As a continuous variable, weight change was not associated with adverse pathology or BCR (all P>0.05). In secondary analysis, on multivariate analysis, men gaining ≥ 2.5 kg were at higher BCR risk (hazards ratio=1.65, 95% confidence interval (CI): 1.03-2.64, P=0.04) while weight loss ≥ 2.5 kg was not associated with BCR (hazards ratio=0.83, 95% CI: 0.54-1.29, P=0.41). CONCLUSIONS: As a continuous variable, weight change was not associated with outcome. In secondary hypothesis-generating analyses, weight gain ≥ 2.5 kg in the year before surgery, regardless of final body mass index, was associated with increased BCR following RP. If validated, these data suggest weight gain ≥ 2.5 kg may promote prostate cancer progression.

The influence of hepatic function on prostate cancer outcomes after radical prostatectomy.

Prostate growth is dependent on circulating androgens, which can be influenced by hepatic function. Liver disease has been suggested to influence prostate cancer (CaP) incidence. However, the effect of hepatic function on CaP outcomes has not been investigated. A total of 1181 patients who underwent radical prostatectomy (RP) between 1988 and 2008 at four Veterans Affairs hospitals that comprise the Shared Equal Access Regional Cancer Hospital database and had available liver function test (LFT) data were included in the study. Independent associations of LFTs with unfavorable pathological features and biochemical recurrence were determined using logistic and Cox regression analyses. Serum glutamic oxaloacetic transaminase (SGOT) and serum glutamic pyruvic transaminase (SGPT) levels were elevated in 8.2 and 4.4% of patients, respectively. After controlling for CaP features, logistic regression revealed a significant association between SGOT levels and pathological Gleason sum > or =7(4+3) cancer (odds ratio=2.12; 95% confidence interval=1.11-4.05; P=0.02). Mild hepatic dysfunction was significantly associated with adverse CaP grade, but was not significantly associated with other adverse pathological features or biochemical recurrence in a cohort of men undergoing RP. The effect of moderate-to-severe liver disease on disease outcomes in CaP patients managed non-surgically remains to be investigated.

The effect of race on the discriminatory accuracy of models to predict biochemical recurrence after radical prostatectomy: results from the Shared Equal Access Regional Cancer Hospital and Duke Prostate Center databases.

To evaluate whether race modifies the accuracy of nomograms to predict biochemical recurrence (BCR) after radical prostatectomy among subjects from the Shared Equal Access Regional Cancer Hospital (SEARCH) and Duke Prostate Center (DPC) databases. Retrospective analysis of 1721 and 4511 subjects from the SEARCH and DPC cohorts, respectively. The discrimination accuracy for BCR of seven previously published predictive models was assessed using concordance index and compared between African-American men (AAM) and Caucasian men (CM). AAM represented 44% of SEARCH and 14% of DPC. In both cohorts, AAM were more likely to experience BCR than CM (P<0.01). In SEARCH, the mean concordance index across all seven models was lower in AAM (0.678) than CM (0.715), though the mean difference between CM and AAM was modest (0.037; range 0.015-0.062). In DPC the overall mean concordance index for BCR across all seven nomograms was 0.686. In contrast to SEARCH, the mean concordance index in DPC was higher in AAM (0.717) than CM (0.681), though the mean differences between CM and AAM was modest (-0.036; range -0.078 to -0.004). Across all seven models for predicting BCR, the discriminatory accuracy was better among CM in SEARCH and better among AAM in DPC. The mean difference in discriminatory accuracy of all seven nomograms between AAM and CM was approximately 3-4%. This indicates that currently used predictive models have similar performances among CM and AAM. Therefore, nomograms represent a valid and accurate method to predict BCR regardless of race.

Preoperative predictors of blood loss at the time of radical prostatectomy: results from the SEARCH database.

The literature contains conflicting data on preoperative predictors of estimated blood loss (EBL) at radical retropubic prostatectomy (RRP). We sought to examine preoperative predictors of EBL at the time of RRP among patients from the SEARCH database to lend clarity to this issue. A total of 1154 patients were identified in the SEARCH database who underwent RRP between 1988 and 2008 and had EBL data available. We examined multiple preoperative factors for their ability to predict EBL using multivariate linear regression analysis. Median EBL was 900 ml (s.d. 1032). The 25th and 75th percentile for EBL were 600 and 1500 ml, respectively. EBL increased significantly with increasing body mass index (BMI) and increasing prostate size and decreased with more recent year of RRP (all P<0.001). The mean-adjusted EBL in normal-weight men (BMI<25 kg/m(2)) was 807 ml compared to 1067 ml among severely obese men (BM I>or=35 kg/m(2)). Predicted EBL for men with the smallest prostates (<20 g) was 721 ml, compared to 1326 ml for men with prostates >or=100 g. Finally, statistically significant differences between centers were observed, with mean-adjusted EBL ranging from 844 to 1094 ml. Both BMI and prostate size are predictors of increased EBL. Prostate size is of particular note, as a nearly twofold increased EBL was seen from the smallest (<20 g) to the largest prostates (>or=100 g). Over time, average EBL significantly decreased. Finally, significant differences in EBL were observed between centers. Patients with multiple risk factors should be forewarned they are at increased risk for higher EBL, which may translate into a greater need for blood transfusion.

Impact of nerve sparing on surgical margins and biochemical recurrence: results from the SEARCH database.

The effects of nerve sparing on the risk of positive surgical margins (PSMs) and biochemical recurrence after radical prostatectomy (RP) remain controversial. We examined data from 1018 men treated by RP between 1988 and 2006 at five centers in the Shared Equal Access Regional Cancer Hospital database. Neither bilateral nor unilateral nerve-sparing techniques were associated with a higher risk of PSM; on multivariate analysis of individual sides, the risk of PSM on either side was not increased by nerve sparing on either side. The risk for biochemical recurrence was not affected by bilateral or unilateral nerve sparing. When used on appropriately selected patients, nerve sparing does not increase the probability of PSM or biochemical recurrence after RP.

Effect of diet and exercise intervention on the growth of prostate epithelial cells.

Epidemiological studies suggest a positive association between nutrient intake, hyperinsulinemia and risk of Benign prostatic hyperplasis (BPH). This study tests the hypothesis that a low-fat, high-fiber diet and daily exercise would lower serum insulin and reduce the growth of serum-stimulated primary prostate epithelial cells in culture. Serum samples were obtained from eight overweight men before and after the Pritikin residential, 2-week diet and exercise intervention and from seven men who were long-term followers of the low-fat, high-fiber diet and regular exercise lifestyle. The serum was used to stimulate primary prostate epithelial cells in culture. Growth was measured after 48 and 96 h and apoptosis after 96 h. At 48 h there was no significant difference in growth within the Pre, 2-week or Long-Term groups. At 96 h growth was significantly reduced in the 2-week (13%) and in the Long-Term (14%) groups compared to the Pre data. At 96 h, apoptosis was not significantly different among the three groups. Fasting insulin was reduced by 30% in the 2-week group and by 52% in the Long-Term group compared to the Pre data. Testosterone was unchanged in the 2-week group. The results of this study indicate that a low-fat, high-fiber diet and daily exercise lowers insulin and reduces growth of prostate primary epithelial cells and suggests that lifestyle may be an important factor in the development or progression of BPH. Future prospective trials should address the effects of this lifestyle modification on BPH symptomatology and progression.

Feasibility of a low-fat/high-fiber diet intervention with soy supplementation in prostate cancer patients after prostatectomy.

OBJECTIVES: To evaluate the feasibility and long-term compliance with a low-fat diet supplemented with soy protein in men at increased risk for recurrence after radical prostatectomy. DESIGN: Randomized, control study. SETTING: Academic center in USA. SUBJECT: Forty men who had undergone radical prostatectomy and were at increased risk for recurrence. INTERVENTION: Low-fat (15% fat), high-fiber (18 g/1000 kcal) diet supplemented with 40 g soy protein isolate (n=26) was compared to USDA recommended diet (n=14). RESULTS: Over 4 years, subjects in the intervention group but not in the control group made and sustained significant changes in their diet as measured by the dietary assessment instruments and urinary isoflavone excretion. In the intervention group, dietary fat intake was reduced from 33.46+/-1.27% energy/day to 21.04+/-1.74% (P<0.05), fiber intake increased from 14.6+/-1.06 to 21.05+/-2.29 g/day. The insulin growth factor-1 (IGF-1) level was decreased from 260.4+/-8.6 ng/ml at baseline to 220.5+/-7.9 ng/ml at 6 months (P<0.05) in the intervention group with no significant change in the control group. An ex vivo assay demonstrated inhibition of LNCaP cell growth (-20.0+/-7.7%, P<0.05) by sera from patients in the intervention group after 6 months of dietary change compared to baseline. CONCLUSION: These data suggest that long-term low-fat dietary interventions as part of prospective randomized trials in prostate cancer survivors are feasible, and lead to reductions in circulating hormones or other growth factors stimulating prostate cancer growth ex vivo.

Impact of diet on prostate cancer: a review.

Epidemiological studies suggest that environmental factors may mediate the transformation of latent prostate cancer into clinically apparent tumors and that diet appears to influence this progression. Close correlations between average per capita fat intake and prostate cancer mortality internationally generated interest in underlying mechanisms for this link, such as through serum levels of androgens, free radicals, proinflammatory fatty acid metabolites, or insulin-like growth factor. Much interest currently lies in the potential of HMG-CoA reductase inhibitors (statins) to play a chemopreventative role in prostate cancer. Lycopene, a potent antioxidant found in tomatoes, may exert a protective effect in the prostate. Selenium and vitamin E have also been shown to decrease the risk of prostate cancer in some men. Calcium may support vitamin D-related antiproliferative effects in prostate cancer. Certain soy proteins, common in the Asian diet, have been shown to inhibit prostate cancer cell growth. Finally, green tea may also have a chemopreventive effect by inducing apoptosis. Despite confounding factors present in clinical studies assessing the effect of diet on cancer risk, the data remain compelling that a variety of nutrients may prevent the development and progression of prostate cancer.

Is there a difference in outcome after radical prostatectomy between patients with biopsy Gleason sums 4, 5, and 6? Results from the SEARCH database.

PURPOSE: Fewer patients newly diagnosed with prostate cancer today have biopsy Gleason sums <6 compared to several years ago. Several tables and nomograms for predicting disease recurrence after definitive therapy provide little or no discrimination between biopsy Gleason sums 4, 5, and 6. We sought to examine the significance of biopsy Gleason sum for predicting biochemical failure following radical prostatectomy (RP) for men with biopsy Gleason sums of 4, 5, and 6. MATERIALS AND METHODS: We examined data from 988 men treated with RP between 1988 and 2002 who had biopsy Gleason sums of 4-6. Clinical and pathological variables as well as outcome information were compared between men with biopsy Gleason sums of 4-6. The log-rank and Cox proportional hazards analysis were used to determine whether biopsy Gleason sum provided unique prognostic information for men with low biopsy Gleason sums undergoing RP. RESULTS: There was statistically significant, but overall weak correlation between biopsy Gleason sum and Gleason sum of the RP specimen (Spearman's r=0.277, P<0.001). As biopsy Gleason sum increased from 4 to 5 to 6, there was a steady rise (HR=1.31 for each one point increase in Gleason sum, Cox's model) in the risk of PSA failure (P=0.025, log-rank). On multivariate analysis comparing biopsy Gleason sum, preoperative PSA, clinical stage, year of surgery, percent of biopsy cores positive, and age for their ability to predict time to biochemical recurrence, only PSA (HR 2.09, CI 1.56-2.80, P<0.001) and biopsy Gleason sum (HR 1.33, CI 1.05-1.70, P=0.019) were significant independent predictors of PSA failure. CONCLUSIONS: Despite weak correlation between biopsy and pathologic Gleason sum among men with biopsy Gleason sum 4-6 tumors, grade was a significant independent predictor of PSA failure following RP. In the range of 4-6, biopsy Gleason sum acted as a continuous variable for predicting PSA failure. The routine use of Gleason sums 4 and 5 to grade prostate needle biopsy specimens should not be abandoned.

Prostate cancer: another aspect of the insulin-resistance syndrome?

Insulin resistance and compensatory hyperinsulinaemia are thought to be the underlying factors in the metabolic or insulin-resistance syndrome and can be controlled by diet and exercise. Hyperinsulinaemia has been shown to have a direct effect on the live, suppressing the production of sex hormone-binding globulin (SHBG) and insulin-like growth factor-binding proteins 1 and 2 (IGFBP-1, -2) while stimulating the production of insulin-like growth factor 1 (IGF-1). These factors have been proposed to be important modulators of hormone-related cancers, such as prostate cancer. Men adopting a low-fat diet and daily exercise reduced their levels of serum insulin and IGF-1, while increasing their levels of IGFBP-1 and sex hormone-binding globulin (SHBG). Cell-culture studies with LNCaP prostate cancer cells showed apoptosis of tumour cells and a reduction in serum-stimulated cell growth in the post diet and exercise serum. These results suggest that prostate cancer may be another aspect of the insulin-resistance syndrome and that adopting a low-fat diet combined with regular exercise may reduce the risk for prostate and other hormone-related cancers. This needs to be tested with prospective studies.

Modulation of omega-3/omega-6 polyunsaturated ratios with dietary fish oils in men with prostate cancer.

OBJECTIVES: The results of epidemiologic and animal studies support the role of a low-fat diet supplemented with omega-3 fatty acids contained in fish oil in preventing the development and progression of prostate cancer. As a first step in studying the role of a low-fat, fish oil-supplemented (LF/FOS) diet in a clinical setting, we conducted a prospective study in men with untreated prostate cancer to evaluate whether a 3-month dietary intervention affects the ratio of omega-3 to omega-6 fatty acids in plasma and gluteal fat. In addition, we evaluated the feasibility of studying cyclooxygenase-2 (COX-2) expression in serial prostate needle biopsy specimens before and after the diet. METHODS: Nine men with untreated prostate cancer consumed an LF/FOS diet for 3 months. Plasma, gluteal adipose tissue, and prostate needle biopsy specimens were obtained from each patient before and after the intervention. The fatty acid compositions of the plasma and gluteal adipose tissue were determined by gas-liquid chromatography, and the COX-2 expression in the prostatic tissue specimens was determined by semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR). RESULTS: Short-term intervention with an LF/FOS diet caused a significant increase in the omega-3/omega-6 fatty acid ratio in plasma (P = 0.002) and gluteal adipose tissue (P = 0.002) in men with prostate cancer. The COX-2 expression in prostatic tissue was quantitated by RT-PCR in 7 of 9 patients, and COX-2 expression decreased in 4 of these 7 patients. CONCLUSIONS: A short-term dietary intervention in men with prostate cancer leads to a significant increase in the omega-3/omega-6 fatty acid ratios in plasma and adipose tissue. The potential for this diet to prevent the development and progression of prostate cancer by way of altered COX-2 expression and prostaglandin production in prostatic tissue requires further study.

Evidence of an inhibitory effect of diet and exercise on prostate cancer cell growth.

PURPOSE: A high fat diet and sedentary lifestyle may predispose men to prostate cancer through effects on serum factors such as hormones. We evaluated the effects of a low fat, high fiber diet and exercise intervention on serum stimulated growth of established prostate cancer cell lines. MATERIALS AND METHODS: Fasting serum was obtained from 13 overweight men before and after undergoing an 11-day low fat, high fiber diet and exercise intervention. Serum was also obtained from 8 men who had complied with the regimen for a mean of 14.2 years. Hormone dependent LNCaP and independent PC-3 prostate cancer cell lines were grown in culture medium containing 10% of subject pre-intervention or post-intervention serum and viable cells were counted after 48 hours. Anthropometry, serum free testosterone, lipids and glucose were measured in all subjects. RESULTS: Post-intervention serum from each of the 11-day intervention subjects reduced LNCaP cell growth by a mean of 30% compared with pre-intervention serum from each (p <0.01). LNCaP cell growth in serum from long-term subjects was 15% below that of post-intervention serum (p <0.01). There was no difference in the growth of PC-3 cells when cultured with serum from either intervention group. Serum free testosterone, body weight, glucose and lipids were significantly reduced in 11-day subjects. CONCLUSIONS: A low fat, high fiber diet and exercise intervention resulted in serum changes that significantly reduced the growth of androgen responsive LNCaP prostate cancer cells in vitro.