Circulating cell-free DNA: a promising marker of pathologic tumor response in rectal cancer patients receiving preoperative chemoradiotherapy.

PURPOSE: The circulating cell-free DNA (cfDNA) in plasma has been reported to be a marker of cancer detection. The aim of this study was to investigate whether the cfDNA has a role as response biomarker in patients receiving preoperative chemoradiotherapy (CRT) for rectal cancer. METHODS: Sixty-seven patients (median age 61 years; male/female 42/25) who underwent CRT for rectal cancer were evaluated. After tumor regression grade (TRG) classification was made, the patients were classified as having disease that responded (TRG 1-2) and that did not respond (TRG 3-5) to therapy. Plasma samples were obtained from patients before and after CRT. The cfDNA levels were analyzed by quantitative real-time polymerase chain reaction of ß-globin. On the basis of the Alu repeats, the cfDNA was considered as either total (fragments of 115 bp, Alu 115) or tumoral (fragments of 247 bp, Alu 247). The association between the pre- or post-CRT levels and between variations during CRT of the Alu 247, Alu 115 repeat, and Alu 247/115 ratio (cfDNA integrity index) and the pathologic tumor response was analyzed. RESULTS: The baseline levels of cfDNA were not associated with tumor response. The post-CRT levels of the cfDNA integrity index were significantly lower in responsive compared to nonresponsive disease (P = 0.0009). Both the median value of the Alu 247 repeat and the cfDNA integrity index decreased after CRT in disease that responded to therapy (P < 0.005 and P < 0.005, respectively) compared to disease that did not respond to therapy (P = 0.83 and P = 0.726, respectively). The results of the multivariable logistic regression analysis showed that only the cfDNA integrity index was significantly and independently associated with tumor response to treatment. CONCLUSIONS: The plasma levels of the longer fragments (Alu 247) of cfDNA and the cfDNA integrity index are promising markers to predict tumor response after preoperative CRT for rectal cancer.

Psychological well-being outcomes in disease-free survivors of mid-low rectal cancer following curative surgery.

OBJECTIVE: The aim of this cross-sectional study was to evaluate psychological well-being outcomes in disease-free survivors who previously underwent radical surgery for rectal adenocarcinoma. METHODS: All patients with rectal adenocarcinoma who underwent primary surgery at a single institution from 1990 to 2002 were considered for inclusion in the study. We identified and sent questionnaires to 145 patients after excluding those who had died or had recurrent disease. One hundred and seventeen patients (men/women: 74/43; median age: 65 years) returned the questionnaires. Patients' well being was evaluated using the Psychological General Well-Being Index (PGWBI) questionnaire. The mean PGWBI score was compared with normative data of the general population. The impact of patient-, tumor- and treatment-related factors on patients' long-term psychological well-being status was also evaluated. RESULTS: Compared with the general population, study patients had significantly better anxiety, depressed mood, positive well being, general health, vitality scales and global index scores. On multivariate analysis, positive well being was independently affected by time from diagnosis (36 months; p=0.025) and occurrence of early major complications (p=0.024). Variables that were independently associated with worse self-control included primary education (p=0.04) and the presence of fecal urgency (p=0.049). General health was negatively affected by time from diagnosis (36 months; p=0.047) and fecal urgency (p=0.009). CONCLUSIONS: Patients who have survived cancer are likely to re-evaluate the importance of everyday events and this may explain why they had better PGWBI scores. This study also identified that a short time from diagnosis, early adverse events and bowel dysfunction had a negative impact on patients' well being.

Health-related quality of life, faecal continence and bowel function in rectal cancer patients after chemoradiotherapy followed by radical surgery.

PURPOSE: To evaluate health-related quality of life (HRQOL), faecal continence and bowel function of patients with rectal cancer who underwent preoperative chemoradiotherapy (pCRT) in a cross-sectional setting. METHODS: Out of 185 consecutive patients who underwent pCRT for rectal cancer from 1994 to 2004 at a single institution, 101 were eligible for the study. Causes of exclusion were: death (n = 38), not radical surgery or recurrence (n = 21), presence of stoma at the time of the survey (n = 15), lost to follow-up (n = 6) and miscellaneous (n = 4). Eligible patients were asked to complete: the European Organisation for Research and Treatment of Cancer (EORTC) QLQ-C30, the disease specific colorectal module (EORTC QLQ-CR38) and faecal incontinence and bowel function questionnaires. HRQOL outcomes were compared with reference data from the general population, and the association among clinical variables and HRQOL was also investigated with linear regression analyses. RESULTS: Questionnaires were completed by 80% of eligible patients. Compared to population-based norms, patients showed clinically meaningful worse outcomes in terms of constipation and diarrhoea. Stool fractionation (p < 0.01) and use of enema/laxative (p < 0.01) were negatively associated with global health status/QOL. Urgency negatively affected physical (p < 0.01), role (p < 0.01) and social functioning (p < 0.01). Sensation of incomplete evacuation negatively affected social functioning (p < 0.01). CONCLUSIONS: Although HRQOL profile of these patients is broadly similar to that of healthy subjects, there are still important limitations in terms of key symptoms. The use of validated questionnaires is crucial to provide standardised information on relevant health status areas.

Long-term oncologic results and complications after preoperative chemoradiotherapy for rectal cancer: a single-institution experience after a median follow-up of 95 months.

BACKGROUND: This study sought to evaluate the long-term outcome and complications, and occurrence of second malignancy after preoperative chemoradiotherapy (pCRT) for rectal cancer. METHODS: One hundred twenty-three consecutive patients (78 men, 45 women) with locally advanced mid-low rectal cancer underwent pCRT between 1994 and 2002. Patients were followed up by one surgeon with a standard protocol, and data were prospectively recorded in a dedicated database. No patient was lost to follow-up. Complications were defined as late if they occurred >6 months after surgery. Overall and disease-free survival were calculated by the Kaplan-Meier method. RESULTS: Of 123 patients, 111 underwent an R0 procedure. The rate of pathologic complete response was 16% (n = 20 patients). At a median follow-up of 95 (range, 56-160) months, 50 late complications occurred in 41 patients, 21 of whom required surgery. In seven cases, the complications were clearly CRT related and were significantly associated with the total dose of radiation delivered (P < .05). The estimated 5- and 10-year overall survival was 76% and 67%, respectively. The estimated 5- and 10-year disease-free survival was 83% and 82%, respectively. In 18 of 19 patients who experienced recurrence (local, n = 3; distant, n = 16), it occurred within 48 months from surgery. The most frequent site of metastasis as first site of recurrence was the lung (9 of 19). The most frequent second primary malignancy was lung cancer (3 of 8). CONCLUSIONS: Despite satisfactory oncological outcome, late morbidity after pCRT is relevant and related to the radiotherapy dose used. Most recurrences and second malignancies were located in the lung.

Rectal cancer adjuvant chemotherapy: when is more useful?

UNLABELLED: THE AIM of the study was to evaluate time-to-progression (TTP) of rectal cancer in a group of patients receiving adjuvant chemotherapy (CHT) after combined neoadjuvant treatment. A secondary end-point was to identify the possible influence of clinical TNM (cTNM) or pathological TNM (pTNM) on TTP and overall survival (OS). PATIENTS AND METHODS: From January 2000 to December 2005, 101 consecutive rectal cancer patients who had been neoadjuvantly treated and had underne adjuvant CHT were retrospectively examined. The variables considered were age, gender and clinical and pathological effect of CHT administration. RESULTS: The mean age was 59 years (29-78 years) and the male:female ratio, 61:40. Forty-two patients had a lower (< or =5 cm from the anal verge), 54 a middle (from 6 to 10 cm) and 5 a higher (=10 cm) rectal lesion. All the patients had received the full course of neoadjuvant radiotherapy (RT) while 26.7% patients had received a reduced number of neoadjuvant CHT cycles. All the patients had undergone surgery and had received adjuvant chemotherapy which was completed in only 77.2% of the cases. Tumour down-staging and complete remissions were reported in 75.2% and 14.8% of cases, respectively. TTP and OS at 3 years were 81.2% and 91.1%, respectively. Out of locally recurrent patients, 77.8% were N+ (p=0.0026) at the pathological evaluation. CONCLUSION: In our series, neither administration of oxaliplatin-based adjuvant chemotherapy (p=0.44) nor age > or =70 years (p=0.51), clinical stage III (p=0.67), tumour down-staging (p=0.44) and achievement of pCR (p=0.66) appeared to have a significant impact on TTP; only pN+ (patients "not responders" to a neoadjuvant CHT-RT) influenced local relapse requiring more accurate postoperative treatment and confirming the literature data about the utility of adjuvant therapy in stage III disease.

Health-related quality of life outcomes in disease-free survivors of mid-low rectal cancer after curative surgery.

BACKGROUND: The main objective of this study was to investigate health-related quality of life (HRQOL) in terms of symptoms and functional outcomes in disease-free survivors of rectal cancer. METHODS: Consecutive patients (n = 117) who underwent curative surgery for rectal cancer with a minimum of 2 years' follow-up and whose disease had not recurred were asked to complete the European Organization for Research and Treatment of Cancer QLQ-C30 and its colorectal cancer module (QLQ-CR38). Long-term HRQOL outcomes were compared with reference data from the general population. Relevant clinical data including type of surgery, stage of disease, type of treatment, and early and late complications were collected. Univariate and multivariate regression analyses were performed to investigate associations among covariates. RESULTS: HRQOL functional aspects were similar with that of an age- and sex-matched general population. Although clinically meaningful better outcomes favoring our patients were found for the global health status/HRQOL and the pain scales, constipation was worse in rectal cancer survivors than the general population. Multivariate analysis found that worse physical functioning was associated with increasing age (P < .001), female sex (P < .01), presence of stoma (P < .05), and occurrence of late major complications (P < .05). Worse body image was associated with the presence of stoma (P < .001) and chemoradiotherapy (P < .05). CONCLUSION: Overall, patients with rectal cancer recover well in the long run, with HRQOL levels comparable to that of the general population. HRQOL outcomes provide valuable data that may be used to improve information disclosure to patients.

Neoadjuvant chemoradiotherapy with 5-fluorouracil by bolus.

BACKGROUND: Neoadjuvant chemoradiotherapy (CT-RT) with continuous infusion (c.i.) 5-fluorouracil (5-FU) before resection of high-risk rectal cancer improves overall survival (OS) and pelvic control. Since the presence of cardiomiopathy may contraindicate c.i. of 5-FU, an alternative regimen of 5-FU CT-RT was prospectively studied in these patients. PATIENTS AND METHODS: From October 2000 to December 2006, patients with clinical stage T3 or T4, or node-positive disease were assigned according to their cardiological status to receive weekly 5-FU bolus administration during radiotherapy (RT). The preoperative treatment consisted of 5,040 cGy, delivered infractions of 180 cGy per day, five days per week, and 5-FU, given in 15 minutes at a dose of 450 mg/m2 of body surface area weekly during all radiotherapy. Surgery was performed six weeks after the completion of CT-RT. The primary endpoint was disease-free survival (DFS). RESULTS: Fifty-one patients received preoperative CH-RT. The 2-year OS rate was 92.3% and the 3-year DFS was 87.5%. The five-year cumulative incidence of local relapse was 3.9%. Grade 3 acute toxic effects occurred in 19.6% of the patients; worsening of patient's cardiopathy was never reported. CONCLUSION: Patients with cardiopathy developed similar local control and DFS, toxicity and OS with 5-FU administered weekly by bolus as those reported by literature data.

Role of neoadjuvant treatment in cT3N0M0 rectal cancer.

BACKGROUND: The aim of the study was to evaluate the pathological response (pTNM), local relapse and overall survival (OS) in clinical T3N0M0 (cT3N0M0) rectal cancer after a neoadjuvant chemoradiotherapy (CHT-RT) with 5-fluorouracil (5-FU) continuous infusion (c.i.) (+/- oxaliplatin) or bolus or capecitabine (an oral fluorpyrimidine). A secondary endpoint was to identify the local relapse rate and OS in those patients also receiving an adjuvant chemotherapy. PATIENTS AND METHODS: From January 2000 to January 2006, 48 consecutive cT3N0M0 rectal cancer cases neoadjuvantly treated were retrospectively examined. Variables considered were age, gender, modality of 5-FU administration and tumour site. RESULTS: Median age was 64 years (range, 22-84 years) and the male:female ratio was 28:20. All the patients received the full course of CHT-RT. Twenty-eight patients received c.i. 5-FU neoadjuvant chemotherapy, 17 received bolus 5-FU administration and 3 patients received capecitabine-based therapy. The mean number of chemotherapy weeks was 4.9 (range, 2-6). A total of 85.4% of patients were operated on without relevant postoperative complications but another 4 are awaiting surgery. Twenty-one patients had a lower (< or = 5 cm from the anal verge) and 27 had a middle rectal lesion (from 6 to 10 cm). In those patients with the lower site of lesion, a sphincter-saving (SS) procedure was achieved in 88.9%. Downstaging was reported in 66.7%. Ninety percent of cases are still free from progression after a median follow-up of 22.1 months; 7.5% are dead. CONCLUSION: The down-staging, the good level of SS and the disease-free survival (DFS) obtained here suggests that a neoadjuvant therapy may also be useful for stage II rectal cancer at diagnosis. The use of a postoperative chemotherapy should probably be outlined better.

Primary rectal carcinoma in patients with stage IV resectable disease at diagnosis.

BACKGROUND: Rectal cancer is commonly diagnosed at a precocious stage, but for patients presenting at diagnosis with stage IV disease the best treatment is still undefined. The purpose of this study was to review the feasibility and outcome of multimodality treatment of rectal cancer patients metastatic at diagnosis. PATIENTS AND METHODS: From January 2000 to December 2005, 40 patients with histologically proven stage IV rectal adenocarcinoma (< 12 cm from the anal verge) were examined. Variables considered were age (under or over 65 years), tumour grade, presence of peritoneal carcinomatosis, type of surgery (palliative versus resection). RESULTS: The median age was 61 years (range, 32-83) and 27 were male and 13 female. Seventeen patients with unresectable or potentially resectable metastatic disease received neoadjuvant chemoradiotherapy (CHT-RT) with 5-fluorouracil (5FU) (plus oxaliplatin in 11 cases), radical surgery was performed in almost half of the cases; only in two patients were metastases also resected. If the patient is a candidate for radical surgical resection, the primary tumour should initially be treated as in a patient without metastatic disease and subsequently the primary tumour and metastases should be treated surgically. If the metastases are unresectable, the treatment of the primary lesion, according to the patient's symptoms, should be by palliative CHT. It is still not determined whether RT should be reserved for the symptomatic cases as an alternative to local surgery. In five patients treated with neoadjuvant CHT alone, radical local surgery was performed in two cases. Eighteen symptomatic patients were resected primarily; all of them received a postoperative CHT but only five of them also received postoperative RT. Nevertheless, after a multimodality treatment (neoadjuvant CHT +/- RT) 22.5% achieved a response rate (RR) (one complete remission (CR) and eight partial remission (PR)). Considering that all except two of the patients were locally radically resected and two of them also underwent metastases surgery, the overall RR was 17.5% (four CR and three PR). All of the CR were disease-free and alive after a median follow-up of 19.3 months. Age > or = 65 years had no impact on overall survival (OS), but the presence of peritoneal carcinosis in five patients showed a trend towards diminished survival, although it was not statistically significant (p = 0.08). CONCLUSION: The best treatment on diagnosis of metastatic rectal cancer is a multimodality CHT-RT approach. New prospective studies should evaluate non cross-resistant regimens as additional therapy for those patients with a systemic residual disease after common CHT-RT.

Rectal cancer neoadjuvant treatment in elderly patients.

BACKGROUND: The aim of the study was to evaluate the differences in terms of toxicity and feasibility of neoadjuvant 5-fluorouracil (5FU) continuous infusion (c.i.) or bolus in combination with pelvic radiotherapy (RT) in locally advanced rectal cancer "fit" or "vulnerable" elderly patients. A secondary endpoint was to identify any specific comorbidity that affected either effectiveness or morbidity of treatment. PATIENTS AND METHODS: From June 2000 to June 2005, 36 patients over 70 years of age out of a total of 88 consecutive elderly cases were retrospectively examined. Variables considered were age, gender, modality of 5FU administration and comorbidities (evaluated according to Cumulative Illness Rating Scale-Geriatric, CIRS-G). RESULTS: Median age was 74 years (range, 70-82) years and the male:female ratio, 22:14. Fourteen % of the patients healthy and 25% with slight comorbidities were considered "fit" and 61% "vulnerable". All the patients received the full course of RT. The mean number of chemotherapy weeks was 5.34 (range, 2-6); "vulnerable" patients did not experience higher toxicity compared to "fit" patients (p = 0.69). Eighty-nine % of the patients were operated without relevant postoperative complications. Thirteen out of 20 "vulnerable" and 10 out of 12 "fit" patients had a pathological downstaging of disease (p = 0.24). CONCLUSION: Selected elderly "vulnerable" patients with rectal cancer can receive the same neoadjuvant 5FU-based chemoradiotherapy (either bolus or c.i.) and undergo surgery as well as "fit" elderly patients, since tolerability and response rate seem to be similar in both categories of patients.

5-fluorouracil and weekly oxaliplatin combined with radiotherapy for locally advanced rectal cancer: surgical complications and long-term results.

BACKGROUND: We undertook this study to evaluate early surgical complications and long-term results after preoperative radiotherapy and chemotherapy (RCT) using 5-fluorouracil (5-FU) and oxaliplatin (OXA) for rectal cancer. METHODS: Forty six TNM stage II-III rectal cancer patients were studied, who were given preoperative RT (50.4 Gy/28 fractions) combined with 5-FU (200-225 mg/m(2)/day by continuous venous infusion) and weekly OXA (25-60 mg/m(2)). Major complications and reoperations were recorded overall, whereas outcome analyses were performed only for patients who received the recommended regimen dosage. RESULTS: Forty three patients (M:F, 25:18; median age 59 years) were available for analysis. All patients received the planned RT dose. There were no postoperative deaths; seven patients had early major surgical complications, four requiring re-operation. One additional patient had a second surgical procedure due to a duodenal fistula complicating the resection of an aortic aneurysm performed concomitantly with rectal cancer surgery. At a median follow-up of 49 months, two of the 23 patients treated at the recommended doses developed recurrence (one local, and one local and distant), and two died of cancer progression. Following the Kaplan-Meier method, the estimated 5-year overall and disease-free survival rates were 92 and 89%, respectively. CONCLUSIONS: The preoperative RCT regimen used in the present study incurs a low rate of recurrence with an acceptable surgical morbidity.

Relationship between pathologic T-stage and nodal metastasis after preoperative chemoradiotherapy for locally advanced rectal cancer.

BACKGROUND: We investigated the relationship between pathologic T-stage and mesorectal metastases after preoperative chemoradiotherapy (CRT) for clinical stage II to III rectal carcinoma. METHODS: The records of consecutive patients with clinical stage II to III carcinoma of the mid or low rectum who underwent surgery after CRT were reviewed. Indications for preoperative CRT were cancer up to 11 cm from the anal verge, Eastern Cooperative Oncology Group performance status of 0 to 2, age 18 to 75 years, and clinical tumor-node-metastasis stage II or III. RESULTS: The study group consisted of 235 patients (148 men and 87 women; median age, 61 years). The pretreatment tumor-node-metastasis stage was as follows: I, n = 1; II, n = 96; and III, n = 138. Radiotherapy was delivered at a median dose of 50.4 Gy. A pathologic complete response on the rectal wall was found in 24% of patients, and nodal metastases were found in 20% of patients. According to the pT stage, the rate of node positivity was 2% for pT0, 15% for pT1, 17% for pT2, 38% for pT3, and 33% for pT4 cases. At multivariate analysis, the best model for predicting pathologic node involvement included young age, positive pretreatment N status, and pT status. On considering pT stage alone, the odds ratio was in the region of 10 for pT1/2 and >20 for pT3/4 patients. CONCLUSIONS: In patients with pT0 after preoperative CRT for clinical stage II to III mid or low rectal cancer, the risk of nodal metastases is very low. More conservative surgery (local excision) may be considered in these cases.

Complete pathologic response following preoperative chemoradiation therapy for middle to lower rectal cancer is not a prognostic factor for a better outcome.

PURPOSE: The aim of this study was to evaluate factors associated with pathologic tumor response following pre-operative chemoradiation therapy, and the prognostic impact of pathologic response on overall and disease-free survival. METHODS: Between 1994 and 2002, 132 patients underwent chemoradiation therapy followed by surgery for middle to lower rectal cancer. After excluding 26 cases (metastatic cancer, n = 13; nonradical surgery, n = 6; local excision procedure, n = 4; non-5-fluorouracil-based chemotherapy, n = 2; incomplete data on preoperative chemoradiation therapy regimen used, n = 1), the remaining 106 patients were included in the study. Variables considered were the following: age, gender, tumor location, pretreatment T and N stage, modality of 5-fluorouracil administration, total radiotherapy dose delivered, chemoradiation therapy regimen used (Regimen A: chemotherapy (bolus of 5-fluorouracil and leucovorin, days 1-5 and 29-33) + radiotherapy (45 Gy/25 F/1.8 Gy/F); Regimen B: chemotherapy (5-fluorouracil continuous venous infusion +/- weekly bolus of carboplatin or oxaliplatin) + radiotherapy (50.4 Gy/28 F/1.8 Gy/F)), time interval between completion of chemoradiation therapy and surgery, postoperative chemotherapy administration, surgical procedures, pT, pN, and pTNM stage, and response to chemoradiation therapy defined as tumor regression grade, scored from 1 (no tumor on surgical specimen) to 5 (absence of regressive changes). Statistical analysis was performed by means of logistic regression analysis (Cox's model for overall and disease-free survival). RESULTS: Median age of the 106 patients was 60 (range, 31-79) years and the male:female ratio, 66:40. Median distance of tumor from the anal verge was 6 (range, 1-11) cm. Pretreatment TNM stage, available in 104 patients, was cT3T4N0, n = 41; cT2N1, n = 9; cT3N1, n = 39; and cT4N1, n = 17. The median radiotherapy dose delivered was 50.4 (range, 40-56) Gy; 58 patients received 5-fluorouracil by continuous venous infusion, and carboplatin with oxaliplatin was added to the chemotherapy schedule in 71 cases. Patients were given Regimen A in 47 cases and Regimen B in 59. The median interval between chemoradiation therapy and surgery was 42.5 (range, 19-136) days, and 94 patients underwent a sphincter-saving procedure. Tumor regression grade, available in 104 cases, was 1, n = 19; 2, n = 18; 3, n = 15; 4, n = 13; and 5, n = 39. At a median follow-up of 42 (range, 1-110) months, 11 patients had died, and 95 were alive. None of the patients had local recurrences, but 13 had distant recurrences. At logistic regression analysis, the chemoradiation therapy regimen used was the only independent predictor of tumor response following preoperative chemoradiation therapy (odds ratio = 0.29, 95% confidence interval = 0.13-0.67, P = 0.003). At Cox's regression analysis, pretreatment T stage was the only independent prognostic factor for both disease-free survival (relative risk = 7.13, 95% confidence interval = 2.3-21.8, P = 0.001) and overall survival (relative risk = 4.83, 95% confidence interval = 1.1-19.9, P = 0.029). CONCLUSIONS: Tumor response following preoperative chemoradiation therapy is mainly related to the preoperative regimen used. For patients receiving preoperative chemoradiation therapy, pretreatment T stage, but not tumor response to preoperative chemoradiation therapy, is prognostic for outcome (both disease-free and overall survival).

Early-age-at-onset colorectal cancer and microsatellite instability as markers of hereditary nonpolyposis colorectal cancer.

PURPOSE: Early-age-at-onset colorectal cancer and microsatellite instability are characteristic features of hereditary nonpolyposis colorectal cancer. Our aim was therefore to investigate whether these features might be useful markers in screening for hereditary nonpolyposis colorectal cancer and mismatch repair gene mutations. METHODS: From 1,132 consecutive patients who underwent surgery for colorectal cancer at our department between 1980 and 1999, we selected all patients 40 years of age or younger (study group, n = 59) and a subset of patients 40 years of age or older (control group, n = 60) who were matched for gender and pathologic TNM stage. Patients for whom a complete family cancer history or microsatellite status was unavailable were excluded from the study. Family cancer histories, retrieved from archival charts, were reassessed. Microsatellite status was investigated with the five microsatellites from the Bethesda recommended panel (BAT-26, BAT-25, D2S123, D5S346, and D17S250). On the basis of the number of altered microsatellites (> or = 2, 1, or 0), tumors were considered as having high or low instability or microsatellite stability, respectively. Mutation analysis for MLH1 and MSH2 genes was performed only in cases of high instability. DNA was investigated for mutations by single-strand conformational polymorphism and sequencing analysis. RESULTS: Data from 95 patients (study group: n = 37, 18 males, mean age 35 years; control group: n = 58, 29 males, mean age 62 years) were available for analysis. Four patients (study group, n = 3; control group, n = 1) fulfilled the Amsterdam II criteria for hereditary nonpolyposis colorectal cancer. Of the 37 study group tumors, 12 (32.4 percent) showed high-frequency microsatellite instability, and 25 had microsatellite stability, whereas among the 58 control group tumors, 4 (7 percent) showed high-frequency microsatellite instability, and 54 had microsatellite stability (P < 0.002). Mismatch repair gene mutation analysis was performed in 12 cases (study group, n = 7; control group, n = 5). We found four mutations (MSH2 119delG, MLH1 ex9 684insT, MSH2 Gln239Stop, and MLH1 del0.8 Kb) in the study group patients and none in the control group. Of four hereditary nonpolyposis colorectal cancer patients who underwent mismatch repair gene mutation analysis, one had a mutation. CONCLUSIONS: Early-age-at-onset colorectal cancer is significantly correlated with high-frequency microsatellite instability tumor status and is a useful criterion to identify hereditary nonpolyposis colorectal cancer patients. Moreover, when used in association with high-frequency microsatellite instability status, it is effective in selecting patients for mismatch repair gene mutation analysis.