Molecular epidemiologic studies within the Selenium and Vitamin E Cancer Prevention Trial (SELECT).

OBJECTIVE: To conduct timely epidemiologic investigations of molecular/genetic markers that may contribute to the development of prostate, lung, colorectal, or other cancers within the Selenium and Vitamin E Cancer Prevention Trial (SELECT), and to evaluate interactions between these markers and the study interventions. METHODS: The epidemiologic studies within SELECT will be based on 32,400 men aged 55 years or older (age 50 or older for the African-American men) enrolled into an intergroup, randomized, placebo-controlled, double-blind, phase III prevention trial of supplemental selenium and vitamin E developed and funded by the National Cancer Institute, and coordinated by the Southwest Oncology Group. During the 12-year study period approximately 1500-2000 cases of prostate cancer, 800 lung cancers, and 500 colon cancers are estimated to be diagnosed, based on data from the ongoing Prostate Cancer Prevention Trial of finasteride. A modified fasting blood sample will be processed to collect plasma for analysis of micronutrients, hormones, cytokines, and other proteins. Buffy-coat derived white blood cells collected at baseline will be used for isolation of DNA and establishment of immortalized cell lines. Red blood cells will be stored for analysis of hemoglobin adducts and other components. RESULTS: Specific results anticipated from these molecular studies will provide information on factors hypothesized to contribute to prostate cancer risk and that may modify the efficacy of either trial supplement, including: steroid sex hormones and several polymorphic genes that encode proteins affecting androgenic stimulation of the prostate, including the androgen receptor, steroid 5alpha-reductase type II, CYP17, and beta-hydroxysteroid dehydrogenase; polymorphisms of DNA repair genes and carcinogen metabolism genes, including those involved in the activation of chemical carcinogens to reactive intermediates (e.g., CYP1A1) or the detoxification of reactive intermediates (e.g., glutathione S-transferase M1); DNA and protein adducts; and insulin-like growth factors and leptin. CONCLUSION: SELECT offers an excellent opportunity to conduct molecular epidemiologic investigations to assess gene-environment interactions and their role in prostate, lung, and colon carcinogenesis.

The Prostate Cancer Prevention Trial: Current status and lessons learned.

The Prostate Cancer Prevention Trial is the first phase 3 prevention trial for prostate cancer in the United States. The implementation of a large, randomized trial has provided a wealth of information that will aid in future cancer chemopreventive studies in US men. The experience from the implementation of the Prostate Cancer Prevention Trial was reviewed. Lessons learned from the study include: (1) US men are willing to enroll in prevention trials; (2) participants in chemoprevention trials are well educated and healthy; (3) the successful cancer prevention trial is viewed by participants as a "men's health trial"; (4) data management and discipline coordination at participating institutions are critical; (5) study design change is commonly required owing to changes in clinical practice over the course of the trial; and (6) training of institutional staff is essential. With proper design, robust data management, and a flexible staff, large-scale randomized chemoprevention trials can be accomplished in the United States. With the extraordinary number of potential agents, it is expected that much will be accomplished with this strategy in the near future.

Profile of men randomized to the prostate cancer prevention trial: baseline health-related quality of life, urinary and sexual functioning, and health behaviors.

PURPOSE: To describe men who agreed to be randomized to the Prostate Cancer Prevention Trial (PCPT), a 7-year, double-blind placebo-controlled study of the efficacy of finasteride in preventing prostate cancer. METHODS: Comprehensive health-related quality-of-life data are presented for 18,882 randomized PCPT participants. RESULTS: PCPT participants are highly educated, middle to upper income, and primarily white (92%). Participants reported healthy lifestyles. The mean American Urological Association Symptom Index score was well below the maximum entry score of less than 19; existing urinary symptoms were generally not bothersome. The scores for two sexual functioning scales could range from 0 to 100, with higher scores reflecting worse sexual functioning. The mean score for the Sexual Problem Scale was 19.2 out of 100, and the mean Sexual Activities Scale was 44.1 out of 100. Scores for seven of the eight Medical Outcomes Study 36-item Short-Form Health Survey scales (higher scores are better) were 10 to 20 points higher than those reported by a general population sample and differed minimally by race but not by age. Previously reported associations between sexual dysfunction and hypertension, diabetes, and depression were also observed. Men who never smoked reported less sexual dysfunction than did those who either had quit or still smoked. CONCLUSION: Individuals who are likely to enroll in primary prevention trials have a high socioeconomic status, healthy lifestyle behaviors, and better health than the general population. These data help oncologists design chemoprevention trials with respect to the selection of health-related quality-of-life assessments and recruitment strategies.

Comparison of young clinical investigators' accuracy and reproducibility when measuring pulmonary and skin surface nodules using a circumferential measurement versus a standard caliper measurement: American Association for Cancer Research/American Society of Clinical Oncology Clinical Trials Workshop.

PURPOSE: The clinical investigator must understand that errors in measuring tumors can greatly affect such clinical-trial end points as tumor response. We performed a prospective, controlled study of tumor measurements that compared circumferential measurements made with a loop planimeter with linear measurements made with a standard caliper. METHODS: Using a cross-over design, 76 clinical oncology fellows/junior oncology faculty members attending a Methods in Clinical Cancer Research Workshop sponsored by the American Association for Cancer Research and the American Society of Clinical Oncology measured five pulmonary nodule phantoms that ranged in size from 1.76 to 13.21 cm(2) and five surface nodule phantoms with sizes ranging from 2.3 to 12.9 cm(2). To perform these measurements, they used both a loop planimeter and a caliper. Forty-two and 40 participants repeated measurements 3 days later on pulmonary and surface nodules. Accuracy, reproducibility, and time efficiency were evaluated. RESULTS: The linear caliper measurements overestimated pulmonary nodule and surface nodule size by a median of 37% and 23%, respectively. Circumferential loop planimeter measurements overestimated pulmonary nodule size and surface nodule size by a median of 8% and 17%, respectively. Interobserver reproducibility for the planimeter was greater than that for the caliper, as evidenced by thinner measurement interquartile ranges. Furthermore, intraobserver reproducibility was higher for the planimeter, with its variability being only 31.4% and 25.5% as large as that of the caliper when measuring the pulmonary and surface nodules, respectively. CONCLUSION: Circumferential measurements provide better accuracy, reproducibility, and speed in measuring both pulmonary and surface nodules than do perpendicular diameters.

Minority recruitment in the prostate cancer prevention trial.

PURPOSE: African American men have a higher prostate cancer risk profile than that of other men in the United States. The purpose of this manuscript is to summarize the challenges associated with enrolling and randomizing African American and other minority participants in the Prostate Cancer Prevention Trial (PCPT). METHODS: The PCPT is a randomized trial of finasteride versus placebo for preventing prostate cancer in healthy men age 55 years and older; it is coordinated by the Southwest Oncology Group. The manuscript describes demographic and lifestyle characteristics of the PCPT randomized sample (18,882 men) by four racial and ethnic groups (Caucasian, African American, Hispanic, and other). African American men comprised 4% of the total randomized sample compared to our goal of 8%. Minority recruitment was emphasized through the Study Manual and training that occurred at trial activation. Supplemental minority recruitment activities were initiated a year after study activation and continued through the end of the accrual period. Minority recruitment was emphasized as follows: minority recruitment presentations at PCPT training seminars (held during twice yearly Southwest Oncology Group meetings); distribution of additional minority recruitment materials; engagement of four consultants for minority recruitment; production of a Minority Recruitment Manual; and a small pilot study involving minority outreach recruiters at five PCPT sites. RESULTS: The consultants were helpful in implementing the pilot project and in suggesting and reviewing materials for minority recruitment. The five-site pilot project did not increase either enrollment or randomization of minorities (with a possible exception at one site). CONCLUSIONS: We suggest that a long-term perspective is required for successful recruitment of minority participants in clinical trials. Likewise, extensive minority recruitment efforts must be ready to implement at trial activation.

Underrepresentation of patients 65 years of age or older in cancer-treatment trials.

BACKGROUND: Studies have documented the underrepresentation of women and blacks in clinical trials, and their recruitment is now federally mandated. However, little is known about the level of participation of elderly patients. We determined the rates of enrollment of patients 65 years of age or older in trials of treatment for cancer. METHODS: We analyzed data on 16,396 patients consecutively enrolled in 164 Southwest Oncology Group treatment trials between 1993 and 1996 according to sex, race (black or white), and age under 65 years or 65 or older. These rates were compared with the corresponding rates in the general population of patients with cancer, derived from the 1990 U.S. Census and from the National Cancer Institute's Surveillance, Epidemiology, and End Results Program for the period from 1992 through 1994. Fifteen types of cancer were included in the analysis. RESULTS: The overall proportions of women and blacks enrolled in Southwest Oncology Group trials were similar to or the same as the estimated proportions in the U.S. population of patients with cancer (women, 41 percent and 43 percent; blacks, 10 percent and 10 percent, respectively). In contrast, patients 65 years of age or older were underrepresented overall (25 percent vs. 63 percent, P<0.001) and in trials involving all 15 types of cancer except lymphoma. The underrepresentation was particularly notable in trials of treatment for breast cancer (9 percent vs. 49 percent, P<0.001). The findings were similar when data on patients who were 70 years of age or older were analyzed, when 15 trials that excluded older patients were eliminated from the analysis, and when community-based enrollment was analyzed separately from enrollment at academic centers. CONCLUSIONS: There is substantial underrepresentation of patients 65 years of age or older in studies of treatment for cancer. The reasons should be clarified, and policies adopted to correct this underrepresentation.

Prostate Cancer Prevention Trial (PCPT) update.

The Prostate Cancer Prevention Trial is an intergroup effort in the USA managed by the Southwest Oncology Group (SWOG) in collaboration with the Eastern Cooperative Oncology Group (ECOG) and the Cancer and Leukemia Group B (CALGB). This 10-year study began approximately 5 years ago and will achieve its primary endpoint in October 2004. At the start of the study, 18,882 men, aged over 55 years, and with normal digital rectal examination (DRE) and serum prostate-specific antigen (PSA) levels of 4.0 ng/ml, a biopsy is recommended. Because of the effect finasteride has on PSA, the PSA value has been indexed to equalize the number of biopsies in both arms. At 7 years all survivors will undergo a sextant biopsy to determine the period prevalence of prostate cancer. The critical assumptions are: (1) finasteride-induced PSA changes result in a simple downward shift; (2) the assessment of adherence is sensitive enough to detect nonadherence affecting PSA level interpretation: (3) factors affecting biopsy loss will be equal in both arms; (4) finasteride does not affect the sensitivity or specificity of DRE on transrectal ultrasound nor the sensitivity of biopsy; (5) bias resulting from transurethral resection of the prostate in benign prostate hyperplasia cases will be negligible.

Army and Air Force leadership in the Prostate Cancer Prevention Trial.

Prostate cancer is now the most common solid tumor in men in the United States. Although the current public health approach to this disease is early diagnosis and treatment, investigations are also focusing on the possibility of disease prevention. The Prostate Cancer Prevention Trial, begun in 1993, has completed recruitment of 18,000 men who will be randomized to receive either finasteride or placebo to determine if finasteride can prevent the development of this disease. Both Army and Air Force institutions are participating in this trial, with four Department of Defense institutions contributing over 10% of the patients randomized. The results of this study may have a major impact on active duty personnel for whom prevention of prostate cancer may become possible.

Chemoprevention of prostate cancer: the Prostate Cancer Prevention Trial.

BACKGROUND: A variety of innovative approaches to the prevention of prostate cancer are now available, including selenium, alpha tocopherol, dietary interventions, and vitamin D. Perhaps the most promising opportunity is based upon considerable evidence that cumulative androgen exposure of the prostate contributes to the age-related risk of prostate cancer. METHODS: The Prostate Cancer Prevention Trial has completed randomization of over 18,000 healthy men to either finasteride or placebo. CONCLUSIONS: While the primary objective of this study is to determine whether finasteride can reduce the period prevalence of prostate cancer over a 7-year period, the biologic and data resources of this study will provide multiple opportunities to better understand this most common cancer in U.S. men.

Prostate cancer clinical trials of the Southwest Oncology Group.

The changing clinical dynamics of prostate cancer have resulted in a broadening of the research focus of the Genitourinary (GU) Cancer Committee of the Southwest Oncology Group (SWOG). Beginning with an emphasis on hormone-refractory disease in its early years, SWOG prostate cancer trials now cover the entire spectrum of the disease: localized, locally advanced, metastatic and hormone-refractory disease. As the world's largest GU cancer research group, the GU committee of SWOG has pioneered studies in combined androgen therapy for metastatic disease, quality-of-life (QOL) assessments for patients with localized and advanced disease, adjuvant therapy models, and prostate cancer chemoprevention. The committee has also formed the GU Global Group, whose purpose is to convene the chairs of the GU committees of all the major national and international oncology cooperative groups. Meeting semiannually, this group discusses activities within their respective organizations, plans collaborative strategies and protocols, and establishes global strategy in prostate cancer clinical research. The future directions of national and international prostate cancer trials will build on this broad foundation of well-conceived, logically sequenced studies.

Screening for prostate cancer: opportunities for prevention.

Although early detection and treatment of prostate cancer is widely advocated, this so-called secondary prevention approach has a number of drawbacks. First, it is not yet certain that active treatment of localized prostate cancer offers any advantage over surveillance. Second, screening may detect indolent tumors while missing some virulent ones. Third, treatment is not uniformly successful, even in patients with early disease. Fourth, radical prostatectomy and radiotherapy are associated with considerable side effects. And finally, the economic and psychological costs of large-scale screening cannot be overlooked. Although attention has been focused on the possibility of primary prevention, neither large-scale dietary manipulation nor long-term prophylactic use of retinoids is considered feasible. With the recent approval of the 5-alpha-reductase inhibitor finasteride for the treatment of benign prostatic hyperplasia, the opportunity for primary chemoprevention has moved closer to reality. The Prostate Cancer Prevention Trial (PCPT), a randomized, placebo-controlled study expected to enroll 18,000 healthy men over the age of 55, is currently addressing the question of whether finasteride prophylaxis can reduce the incidence of prostate cancer over a 7-year period. This is a US government work. There are no restrictions on its use.

Design of the Prostate Cancer Prevention Trial (PCPT).

The PCPT is a chemoprevention trial of finasteride with a primary endpoint of biopsy-proven presence or absence of prostate cancer. A total of 18,000 healthy men, aged 55 years and older, will be randomized. Half will receive finasteride (5 mg/day) and half will receive placebo (one matching tablet per day) for 7 years. The trial is designed to have 92% power to detect a 25% reduction in period prevalence of biopsy-proven disease using a two-sided test with alpha = 0.05. The trial is complicated by the known impact of finasteride on the major screening test for prostate cancer, prostate specific antigen (PSA). This paper describes the PCPT design with reference to alternatives that were considered. The chosen design depends on five critical assumptions that must be monitored closely throughout the 9-year trial.