Accrual Quality Improvement Program for clinical trials.

BACKGROUND: The Early Phase Cancer Prevention Clinical Trials Program (Consortia), led by the Division of Cancer Prevention, National Cancer Institute, supports and conducts trials assessing safety, tolerability, and cancer preventive potential of a variety of interventions. Accrual to cancer prevention trials includes the recruitment of unaffected populations, posing unique challenges related to minimizing participant burden and risk, given the less evident or measurable benefits to individual participants. The Accrual Quality Improvement Program was developed to address these challenges and better understand the multiple determinants of accrual activity throughout the life of the trial. Through continuous monitoring of accrual data, Accrual Quality Improvement Program identifies positive and negative factors in real-time to optimize enrollment rates for ongoing and future trials. METHODS: The Accrual Quality Improvement Program provides a web-based centralized infrastructure for collecting, analyzing, visualizing, and storing qualitative and quantitative participant-, site-, and study-level data. The Accrual Quality Improvement Program approaches cancer prevention clinical trial accrual as multi-factorial, recognizing protocol design, potential participants' characteristics, and individual site as well as study-wide implementation issues. RESULTS: The Accrual Quality Improvement Program was used across 39 Consortia trials from 2014 to 2022 to collect comprehensive trial information. The Accrual Quality Improvement Program captures data at the participant level, including number of charts reviewed, potential participants contacted and reasons why participants were not eligible for contact or did not consent to the trial or start intervention. The Accrual Quality Improvement Program also captures site-level (e.g. staffing issues) and study-level (e.g. when protocol amendments are made) data at each step of the recruitment/enrollment process, from potential participant identification to contact, consent, intervention, and study completion using a Recruitment Journal. Accrual Quality Improvement Program's functionality also includes tracking and visualization of a trial's cumulative accrual rate compared to the projected accrual rate, including a zone-based performance rating with corresponding quality improvement intervention recommendations. CONCLUSION: The challenges associated with recruitment and timely completion of early phase cancer prevention clinical trials necessitate a data collection program capable of continuous collection and quality improvement. The Accrual Quality Improvement Program collects cumulative data across National Cancer Institute, Division of Cancer Prevention early phase clinical trials, providing the opportunity for real-time review of participant-, site-, and study-level data and thereby enables responsive recruitment strategy and protocol modifications for improved recruitment rates to ongoing trials. Of note, Accrual Quality Improvement Program data collected from ongoing trials will inform future trials to optimize protocol design and maximize accrual efficiency.

Repurposing metformin for the prevention of cancer and cancer recurrence.

Multiple epidemiological studies have documented an association between metformin, used for treatment of type 2 diabetes, and reduced cancer incidence and mortality. Cell line models may not accurately reflect the effects of metformin in the clinical setting. Moreover, findings from animal model studies have been inconsistent, whilst those from more recent epidemiological studies have tempered the overall effect size. The purpose of this review is to examine metformin's chemopreventive potential by outlining relevant mechanisms of action, the most recent epidemiologic evidence, and recently completed and ongoing clinical trials. Although repurposing drugs with excellent safety profiles is an appealing strategy for cancer prevention and treatment in the adjuvant setting, there is no substitute for well-executed, large randomised clinical trials to define efficacy and determine the populations that are most likely to benefit from an intervention. Thus, enthusiasm remains for understanding the role of metformin in cancer through ongoing clinical research.

Long-term survival of participants in the prostate cancer prevention trial.

BACKGROUND: In the Prostate Cancer Prevention Trial (PCPT), finasteride significantly reduced the risk of prostate cancer but was associated with an increased risk of high-grade disease. With up to 18 years of follow-up, we analyzed rates of survival among all study participants and among those with prostate cancer. METHODS: We collected data on the incidence of prostate cancer among PCPT participants for an additional year after our first report was published in 2003 and searched the Social Security Death Index to assess survival status through October 31, 2011. RESULTS: Among 18,880 eligible men who underwent randomization, prostate cancer was diagnosed in 989 of 9423 (10.5%) in the finasteride group and 1412 of 9457 (14.9%) in the placebo group (relative risk in the finasteride group, 0.70; 95% confidence interval [CI], 0.65 to 0.76; P<0.001). Of the men who were evaluated, 333 (3.5%) in the finasteride group and 286 (3.0%) in the placebo group had high-grade cancer (Gleason score, 7 to 10) (relative risk, 1.17; 95% CI, 1.00 to 1.37; P=0.05). Of the men who died, 2538 were in the finasteride group and 2496 were in the placebo group, for 15-year survival rates of 78.0% and 78.2%, respectively. The unadjusted hazard ratio for death in the finasteride group was 1.02 (95% CI, 0.97 to 1.08; P=0.46). Ten-year survival rates were 83.0% in the finasteride group and 80.9% in the placebo group for men with low-grade prostate cancer and 73.0% and 73.6%, respectively, for those with high-grade prostate cancer. CONCLUSIONS: Finasteride reduced the risk of prostate cancer by about one third. High-grade prostate cancer was more common in the finasteride group than in the placebo group, but after 18 years of follow-up, there was no significant between-group difference in the rates of overall survival or survival after the diagnosis of prostate cancer. (Funded by the National Cancer Institute.).

Prevention and early detection of prostate cancer.

Prostate cancer is a common malignancy in men and the worldwide burden of this disease is rising. Lifestyle modifications such as smoking cessation, exercise, and weight control offer opportunities to reduce the risk of developing prostate cancer. Early detection of prostate cancer by prostate-specific antigen (PSA) screening is controversial, but changes in the PSA threshold, frequency of screening, and the use of other biomarkers have the potential to minimise the overdiagnosis associated with PSA screening. Several new biomarkers for individuals with raised PSA concentrations or those diagnosed with prostate cancer are likely to identify individuals who can be spared aggressive treatment. Several pharmacological agents such as 5α-reductase inhibitors and aspirin could prevent development of prostate cancer. In this Review, we discuss the present evidence and research questions regarding prevention, early detection of prostate cancer, and management of men either at high risk of prostate cancer or diagnosed with low-grade prostate cancer.

Phase III prostate cancer chemoprevention trials.

Chemoprevention refers to the use of pharmacologic interventions to delay, prevent, or reverse carcinogenesis with the ultimate goal of reducing cancer incidence. Two large, population-based, phase 3 prostate cancer prevention trials reported that 5-alpha reductase inhibitors significantly reduce prostate cancer risk. However, this class of agents were also associated with increased detection of high-grade prostate cancer. Another large, phase 3 prostate cancer prevention clinical trial showed no benefit for long-term supplementation with the trace element Se, given in the form of selenomethionine, or vitamin E, either individually or in combination. Paradoxically, a significant increase in prostate cancer was observed among men randomized to receive vitamin E alone. A great deal of progress had been made in the field of prostate cancer prevention over the past decade. Future studies will focus on prevention of disease progression in men on Active Surveillance, immunotherapy, mechanistically based drug combinations, and novel biomarkers of risk and benefit.

A Systematic Review and Pooled Analysis of Hypothesized versus Observed Effect Sizes in Early Phase Cancer Prevention Clinical Trials.

Early phase cancer prevention trials are designed to demonstrate safety, tolerability, feasibility, and signals of efficacy of preventive agents. Yet it is often observed that many trials fail to detect intervention effects. We conducted a systematic review and pooled analyses of recently completed early phase chemoprevention trials to gain in depth insight on the failure of detecting efficacy signals by comparing hypothesized effect sizes to the corresponding observed effect sizes.Single- or multi-arm efficacy chemoprevention trials conducted under the phase 0/I/II Cancer Prevention Clinical Trials Program of the Division of Cancer Prevention, NCI between 2003 and 2019 were evaluated. A total of 59 chemoprevention trials were reviewed. Twenty-four studies were efficacy or biomarker trials with complete information on hypothesized and observed effect sizes and included in this analysis. The majority of the trials (n = 18) were multi-arm randomized studies of which 15 trials were blinded. The pooled estimate of the observed to hypothesized effect size ratio was 0.57 (95% confidence interval: 0.42-0.73, P < 0.001) based on a random-effects model. There were no significant differences detected in the ratio of observed to hypothesized effect sizes when conducting various subgroup analyses.The results demonstrate that the majority of early phase cancer chemoprevention trials have substantially smaller observed effect sizes than hypothesized effect sizes. Sample size calculations for early phase chemoprevention trials need to balance the potential detectable effect sizes with realistic and cost-effective accrual of study populations, thereby, detecting only intervention effects large enough to justify subsequent large-scale confirmatory trials. PREVENTION RELEVANCE: The results of this systematic review and pooled analyses demonstrate that for early chemoprevention trials, there are substantial differences between hypothesized and observed effect sizes, regardless of study characteristics. The conduct of early phase chemoprevention trial requires careful planning of study design, primary endpoint, and sample size determination.

Report from an NCI Roundtable: Cancer Prevention in Primary Care.

The Division of Cancer Prevention in the NCI sponsored a Roundtable with primary care providers (PCP) to determine barriers for integrating cancer prevention within primary care and discuss potential opportunities to overcome these barriers. The goals were to: (i) assess the cancer risk assessment tools available to PCPs; (ii) gather information on use of cancer prevention resources; and (iii) understand the needs of PCPs to facilitate the implementation of cancer prevention interventions beyond routine screening and interventions. The Roundtable discussion focused on challenges and potential research opportunities related to: (i) cancer risk assessment and management of high-risk individuals; (ii) cancer prevention interventions for risk reduction; (iii) electronic health records/electronic medical records; and (iv) patient engagement and information dissemination. Time constraints and inconsistent/evolving clinical guidelines are major barriers to effective implementation of cancer prevention within primary care. Social determinants of health are important factors that influence patients' adoption of recommended preventive interventions. Research is needed to determine the best means for implementation of cancer prevention across various communities and clinical settings. Additional studies are needed to develop tools that can help providers collect clinical data that can enable them to assess patients' cancer risk and implement appropriate preventive interventions.

Lessons Learned from the Impact of COVID-19 on NCI-sponsored Cancer Prevention Clinical Trials: Moving Toward Participant-centric Study Designs.

The COVID-19 pandemic overloaded health care systems around the globe and brought travel restrictions and other mandates. These effects critically impacted cancer care and conduct of clinical trials, and required medical and research communities to incorporate changes and novel flexible workflows within clinical trials and regulations to improve efficiency. We report the impact of the pandemic on cancer prevention clinical trials managed by the Division of Cancer Prevention within the NCI, focusing on participant-centric, study staff-centric and regulatory elements. Learning lessons from this challenging period, the cancer prevention community has the opportunity to incorporate many of these necessitated novel approaches to future design of clinical trials, to streamline and improve clinical trial efficiency and impact.

Gynecologic conditions in participants in the NSABP breast cancer prevention study of tamoxifen and raloxifene (STAR).

OBJECTIVE: This study reports the gynecologic conditions in postmenopausal women (intact uterus on enrollment) in the National Surgical Adjuvant Breast and Bowel Project (NSABP) study of tamoxifen and raloxifene (STAR)/P-2 trial. STUDY DESIGN: This study, with a median follow-up period of 81 months, evaluated the incidence rates/risks of gynecologic conditions among women who were treated with tamoxifen and raloxifene. RESULTS: Compared with women who received tamoxifen therapy, women who received raloxifene therapy had a lower incidence of uterine cancer (relative risk, 0.55)/endometrial hyperplasia (relative risk, 0.19), leiomyomas (relative risk, 0.55), ovarian cysts (relative risk, 0.60), and endometrial polyps (relative risk, 0.30) and had fewer procedures performed. Women receiving tamoxifen therapy had more hot flashes (P < .0001), vaginal discharge (P < .0001), and vaginal bleeding (P < .0001). CONCLUSION: Our results suggest that tamoxifen has more of an estrogenic effect on the gynecologic reproductive organs. These effects should be considered in counseling women on options for breast cancer prevention.

Vitamin E and the risk of prostate cancer: the Selenium and Vitamin E Cancer Prevention Trial (SELECT).

CONTEXT: The initial report of the Selenium and Vitamin E Cancer Prevention Trial (SELECT) found no reduction in risk of prostate cancer with either selenium or vitamin E supplements but a statistically nonsignificant increase in prostate cancer risk with vitamin E. Longer follow-up and more prostate cancer events provide further insight into the relationship of vitamin E and prostate cancer. OBJECTIVE: To determine the long-term effect of vitamin E and selenium on risk of prostate cancer in relatively healthy men. DESIGN, SETTING, AND PARTICIPANTS: A total of 35,533 men from 427 study sites in the United States, Canada, and Puerto Rico were randomized between August 22, 2001, and June 24, 2004. Eligibility criteria included a prostate-specific antigen (PSA) of 4.0 ng/mL or less, a digital rectal examination not suspicious for prostate cancer, and age 50 years or older for black men and 55 years or older for all others. The primary analysis included 34,887 men who were randomly assigned to 1 of 4 treatment groups: 8752 to receive selenium; 8737, vitamin E; 8702, both agents, and 8696, placebo. Analysis reflect the final data collected by the study sites on their participants through July 5, 2011. INTERVENTIONS: Oral selenium (200 µg/d from L-selenomethionine) with matched vitamin E placebo, vitamin E (400 IU/d of all rac-α-tocopheryl acetate) with matched selenium placebo, both agents, or both matched placebos for a planned follow-up of a minimum of 7 and maximum of 12 years. MAIN OUTCOME MEASURES: Prostate cancer incidence. RESULTS: This report includes 54,464 additional person-years of follow-up and 521 additional cases of prostate cancer since the primary report. Compared with the placebo (referent group) in which 529 men developed prostate cancer, 620 men in the vitamin E group developed prostate cancer (hazard ratio [HR], 1.17; 99% CI, 1.004-1.36, P = .008); as did 575 in the selenium group (HR, 1.09; 99% CI, 0.93-1.27; P = .18), and 555 in the selenium plus vitamin E group (HR, 1.05; 99% CI, 0.89-1.22, P = .46). Compared with placebo, the absolute increase in risk of prostate cancer per 1000 person-years was 1.6 for vitamin E, 0.8 for selenium, and 0.4 for the combination. CONCLUSION: Dietary supplementation with vitamin E significantly increased the risk of prostate cancer among healthy men. TRIAL REGISTRATION: Clinicaltrials.gov Identifier: NCT00006392.

Establishing a Primary Care Alliance for Conducting Cancer Prevention Clinical Research at Community Sites.

In September 2020, the National Cancer Institute convened the first PARTNRS Workshop as an initiative to forge partnerships between oncologists, primary care professionals, and non-oncology specialists for promoting patient accrual into cancer prevention trials. This effort is aimed at bringing about more effective accrual methods to generate decisive outcomes in cancer prevention research. The workshop convened to inspire solutions to challenges encountered during the development and implementation of cancer prevention trials. Ultimately, strategies suggested for protocol development might enhance integration of these trials into community settings where a diversity of patients might be accrued. Research Bases (cancer research organizations that develop protocols) could encourage more involvement of primary care professionals, relevant prevention specialists, and patient representatives with protocol development beginning at the concept level to improve adoptability of the trials within community facilities, and consider various incentives to primary care professionals (i.e., remuneration). Principal investigators serving as liaisons for the NCORP affiliates and sub-affiliates, might produce and maintain "Prevention Research Champions" lists of PCPs and non-oncology specialists relevant in prevention research who can attract health professionals to consider incorporating prevention research into their practices. Finally, patient advocates and community health providers might convince patients of the benefits of trial-participation and encourage "shared-decision making."

Assessment of and Interventions for Women at High Risk for Breast or Ovarian Cancer: A Survey of Primary Care Physicians.

As clinical guidelines for cancer prevention refer individuals to primary care physicians (PCP) for risk assessment and clinical management, PCPs may be expected to play an increasing role in cancer prevention. It is crucial that PCPs are adequately supported to assess an individual's cancer risk and make appropriate recommendations. The objective of this study is to assess use, familiarity, attitude, and behaviors of PCPs regarding breast and ovarian cancer risk and prevention, to better understand the factors that influence their prescribing behaviors. We conducted a cross-sectional, web-based survey of PCPs in the United States, recruited from an opt-in healthcare provider panel. Invitations were sent in batches until the target sample size of 750 respondents (250 each for obstetrics/gynecology, internal medicine, and family medicine) was met. Self-reported use of breast/ovarian cancer risk assessments was low (34.7%-59.2%) compared with discussion of cancer family history (96.9%), breast exams (87.1%), and mammograms (92.8%). Although most respondents (48.0%-66.8%) were familiar with cancer prevention interventions, respondents who reported to be less familiar were more likely to report cautious attitudes. When presented with hypothetical cases depicting patients at different breast/ovarian cancer risks, up to 34.0% of respondents did not select any of the clinically recommended course(s) of action. This survey suggests that PCP use of breast/ovarian cancer risk assessment tools and ability to translate the perceived risks to clinical actions is variable. Improving implementation of cancer risk assessment and clinical management guidelines within primary care may be necessary to improve the appropriate prescribing of cancer prevention interventions.Prevention Relevance: Primary care physicians are becoming more involved in cancer prevention management, so it is important that cancer risk assessment and medical society guideline recommendations for cancer prevention are better integrated into primary care to improve appropriate prescribing of cancer prevention interventions and help reduce cancer risk.

A Polygenic Risk Score Predicts Incident Prostate Cancer Risk in Older Men but Does Not Select for Clinically Significant Disease.

Despite the high prevalence of prostate cancer in older men, the predictive value of a polygenic risk score (PRS) remains uncertain in men aged ≥70 years. We used a 6.6 million-variant PRS to predict the risk of incident prostate cancer in a prospective study of 5701 men of European descent aged ≥70 years (mean age 75 years) enrolled in the ASPirin in Reducing Events in the Elderly (ASPREE) clinical trial. The study endpoint was prostate cancer, including metastatic or non-metastatic disease, confirmed by an expert panel. After excluding participants with a history of prostate cancer at enrolment, we used a multivariable Cox proportional hazards model to assess the association between the PRS and incident prostate cancer risk, adjusting for covariates. Additionally, we examined the distribution of Gleason grade groups by PRS group to determine if a higher PRS was associated with higher grade disease. We tested for interaction between the PRS and aspirin treatment. Logistic regression was used to independently assess the association of the PRS with prevalent (pre-trial) prostate cancer, reported in medical histories. During a median follow-up time of 4.6 years, 218 of the 5701 participants (3.8%) were diagnosed with prostate cancer. The PRS predicted incident risk with a hazard ratio (HR) of 1.52 per standard deviation (SD) (95% confidence interval (CI) 1.33-1.74, p < 0.001). Men in the top quintile of the PRS distribution had an almost three times higher risk of prostate cancer than men in the lowest quintile (HR = 2.99 (95% CI 1.90-4.27), p < 0.001). However, a higher PRS was not associated with a higher Gleason grade groups. We found no interaction between aspirin treatment and the PRS for prostate cancer risk. The PRS was also associated with prevalent prostate cancer (odds ratio = 1.80 per SD (95% CI 1.65-1.96), p < 0.001).While a PRS for prostate cancer is strongly associated with incident risk in men aged ≥70 years, the clinical utility of the PRS as a biomarker is currently limited by its inability to select for clinically significant disease.

A nutrient approach to prostate cancer prevention: The Selenium and Vitamin E Cancer Prevention Trial (SELECT).

The Selenium and Vitamin E Cancer Prevention Trial (SELECT) randomized 35,533 healthy men, >55 yr old (>50 yr if African American), with normal digital rectal exams and prostate specific antigens <4 ng/ml to 1) 200 µg/day l-selenomethionine, 2) 400 IU/day all-rac-alpha-tocopheryl acetate (vitamin E), 3) both supplements, or 4) placebo for 7 to 12 yr. The hypotheses underlying SELECT, that selenium and vitamin E individually and together decrease prostate cancer incidence, derived from epidemiologic and laboratory evidence and significant secondary endpoints in the Nutritional Prevention of Cancer (selenium) and Alpha-Tocopherol Beta-Carotene (vitamin E) trials. In SELECT, prostate cancer incidence did not differ among the 4 arms: hazard ratios [99% confidence intervals (CIs)] for prostate cancer were 1.13 (99% CI = 0.95-1.35, P = 0.06; n = 473) for vitamin E, 1.04 (99% CI = 0.87-1.24, P = 0.62; n = 432) for selenium, and 1.05 (99% CI = 0.88-1.25, P = 0.52; n = 437) for selenium + vitamin E vs. 1.00 (n = 416) for placebo. Statistically nonsignificant increased risks of prostate cancer with vitamin E alone [relative risk (RR) = 1.13, P = 0.06) and newly diagnosed Type 2 diabetes mellitus with selenium alone (RR = 1.07, P = 0.16) were observed. SELECT data show that neither selenium nor vitamin E, alone or together, in the doses and formulations used, prevented prostate cancer in this heterogeneous population of healthy men.

Cancer Prevention in Primary Care: Perception of Importance, Recognition of Risk Factors and Prescribing Behaviors.

PURPOSE: Acceptability and uptake of cancer preventive interventions is associated with physician recommendation, which is dependent on physician familiarity with available preventive options. The goal of this study is to evaluate cancer prevention perceptions, understanding of breast and ovarian cancer risk factors, and prescribing behaviors of primary care physicians. METHODS: We conducted cross-sectional. Web-based survey of 750 primary care physicians (250 each for obstetrics/gynecology, internal medicine, and family medicine) in the United States. Survey respondents were recruited from an opt-in health care provider panel. RESULTS: Perception of importance and the practice of recommending general and cancer-specific preventive screenings and interventions significantly differed by provider type. These perceptions and behaviors reflected the demographics of the population that the primary care physicians see within their respective practices. The majority of respondents recognized genetic/hereditary risk factors for breast or ovarian cancer, while epidemiologic or clinical risk factors were less frequently recognized. Prescribing behaviors were related to familiarity with the interventions, with physicians indicating that they more frequently reinforced a specialist's recommendation rather than prescribed a preventive intervention. CONCLUSIONS: Cancer prevention perceptions, recognition of cancer risk factors, and prescribing behaviors differ among practice types and were related to familiarity with preventive options. Cancer prevention education and risk assessment resources should be more widely available to primary care physicians.

A Phase IIa Trial of Metformin for Colorectal Cancer Risk Reduction among Individuals with History of Colorectal Adenomas and Elevated Body Mass Index.

Obesity is associated with risk of colorectal adenoma (CRA) and colorectal cancer. The signaling pathway activated by metformin (LKB1/AMPK/mTOR) is implicated in tumor suppression in ApcMin/+ mice via metformin-induced reduction in polyp burden, increased ratio of pAMPK/AMPK, decreased pmTOR/mTOR ratio, and decreased pS6Ser235/S6Ser235 ratio in polyps. We hypothesized that metformin would affect colorectal tissue S6Ser235 among obese patients with recent history of CRA. A phase IIa clinical biomarker trial was conducted via the U.S. National Cancer Institute-Chemoprevention Consortium. Nondiabetic, obese subjects (BMI ≥30) ages 35 to 80 with recent history of CRA were included. Subjects received 12 weeks of oral metformin 1,000 mg twice every day. Rectal mucosa biopsies were obtained at baseline and end-of-treatment (EOT) endoscopy. Tissue S6Ser235 and Ki-67 immunostaining were analyzed in a blinded fashion using Histo score (Hscore) analysis. Among 32 eligible subjects, the mean baseline BMI was 34.9. Comparing EOT to baseline tissue S6Ser235 by IHC, no significant differences were observed. Mean (SD) Hscore at baseline was 1.1 (0.57) and 1.1 (0.51) at EOT; median Hscore change was 0.034 (P = 0.77). Similarly, Ki-67 levels were unaffected by the intervention. The adverse events were consistent with metformin's known side-effect profile. Among obese patients with CRA, 12 weeks of oral metformin does not reduce rectal mucosa pS6 or Ki-67 levels. Further research is needed to determine what effects metformin has on the target tissue of origin as metformin continues to be pursued as a colorectal cancer chemopreventive agent.

Selenium and Vitamin E Cancer Prevention Trial: a nutrient approach to prostate cancer prevention.

Prostate cancer continues to be both a major health threat, especially among African-American men, and a public health burden. However, growing evidence suggests that selenium and vitamin E may decrease the risk of this disease. The Selenium and Vitamin E Cancer Prevention Trial (SELECT), a phase III randomized, placebo-controlled study, is designed to determine whether selenium and vitamin E, alone or in combination, decrease the risk of prostate cancer in healthy men. SELECT opened to accrual on 25 July 2001 in more than 400 clinical sites across the United States, Puerto Rico, and Canada; the goal was to randomize 32,400 men. Accrual was completed in June 2004, 2 years ahead of schedule, with a total of 35,534 men randomized. Eligibility requirements include age of at least 55 years (African-American men at least 50 years), and no evidence of prostate cancer as determined by a serum PSA level of no more than 4 ng/ml and a digital rectal exam (DRE) not suspicious for prostate cancer. Participants were randomized to receive selenium (200 microg/ day of l-selenomethionine) and/or vitamin E (400 IU/day of all-rac-alpha-tocopheryl acetate) supplementation for a minimum of 7 years (maximum of 12 years). The rationale for choosing these agents was based on preclinical data as well as analyses of secondary endpoints in cancer prevention clinical trials. The primary endpoint of SELECT is occurrence of prostate cancer based on community standards of diagnosis. Several other non-cancer endpoints are also being explored.

The use of tamoxifen and raloxifene for the prevention of breast cancer.

The NSABP Study of Tamoxifen and Raloxifene (STAR), launched in 1999, compared tamoxifen with raloxifene in a population of healthy postmenopausal women at increased risk for breast cancer to determine the relative effects on the risk of invasive breast cancer. To be eligible for participation, a woman had to be healthy with at least a 5-year predicted breast cancer risk of 1.66% based on the Gail model or a history of lobular carcinoma in situ (LCIS) treated by local excision alone. All participants were at least 35 years of age and postmenopausal. Between July 1999 and November 2004, 19,747 participants were randomized to receive either tamoxifen (20 mg, plus placebo) or raloxifene (60 mg, plus placebo) daily for a 5-year period. The mean age of the participants was 58.5 years; 93% were white and 51.6% had a hysterectomy prior to entering the study. Of the women, 71% had one or more first degree female relatives (mother, sister, daughter) with a history of breast cancer and 9.2% of the women had a personal history of LCIS. A history of atypical hyperplasia of the breast was noted in 22.7% of the participants. The mean predicted 5-year risk of developing breast cancer among the study population was 4.03% (SD, 2.17%) with a lifetime predicted risk of 16%. The mean time of follow-up is 3.9 years (SD, 1.6 years). There was no difference between the effect oftamoxifen and the effect of raloxifene on the incidence of invasive breast cancer; there were 163 cases of invasive breast cancer in the tamoxifen-treated group and 168 cases in those women assigned to raloxifene (incidence 4.30 per 1,000 vs 4.41 per 1,000; RR 1.02; 95% CI, 082-1.28). There were fewer cases of noninvasive breast cancer (LCIS and ductal carcinoma in situ [DCIS]) in the tamoxifen group (57 cases) than in the raloxifene group (80 cases), although the difference is not yet statistically significant (incidence 1.51 vs 2.11 per 1,000; RR, 1.40; 95% CI, 0.98-2.00). There were 36 cases of uterine cancer with tamoxifen and 23 cases with raloxifene (RR, 0.63; 95% CI, 0.35-1.08).

Effect of selenium and vitamin E on risk of prostate cancer and other cancers: the Selenium and Vitamin E Cancer Prevention Trial (SELECT).

CONTEXT: Secondary analyses of 2 randomized controlled trials and supportive epidemiologic and preclinical data indicated the potential of selenium and vitamin E for preventing prostate cancer. OBJECTIVE: To determine whether selenium, vitamin E, or both could prevent prostate cancer and other diseases with little or no toxicity in relatively healthy men. DESIGN, SETTING, AND PARTICIPANTS: A randomized, placebo-controlled trial (Selenium and Vitamin E Cancer Prevention Trial [SELECT]) of 35,533 men from 427 participating sites in the United States, Canada, and Puerto Rico randomly assigned to 4 groups (selenium, vitamin E, selenium + vitamin E, and placebo) in a double-blind fashion between August 22, 2001, and June 24, 2004. Baseline eligibility included age 50 years or older (African American men) or 55 years or older (all other men), a serum prostate-specific antigen level of 4 ng/mL or less, and a digital rectal examination not suspicious for prostate cancer. INTERVENTIONS: Oral selenium (200 microg/d from L-selenomethionine) and matched vitamin E placebo, vitamin E (400 IU/d of all rac-alpha-tocopheryl acetate) and matched selenium placebo, selenium + vitamin E, or placebo + placebo for a planned follow-up of minimum of 7 years and a maximum of 12 years. MAIN OUTCOME MEASURES: Prostate cancer and prespecified secondary outcomes, including lung, colorectal, and overall primary cancer. RESULTS: As of October 23, 2008, median overall follow-up was 5.46 years (range, 4.17-7.33 years). Hazard ratios (99% confidence intervals [CIs]) for prostate cancer were 1.13 (99% CI, 0.95-1.35; n = 473) for vitamin E, 1.04 (99% CI, 0.87-1.24; n = 432) for selenium, and 1.05 (99% CI, 0.88-1.25; n = 437) for selenium + vitamin E vs 1.00 (n = 416) for placebo. There were no significant differences (all P>.15) in any other prespecified cancer end points. There were statistically nonsignificant increased risks of prostate cancer in the vitamin E group (P = .06) and type 2 diabetes mellitus in the selenium group (relative risk, 1.07; 99% CI, 0.94-1.22; P = .16) but not in the selenium + vitamin E group. CONCLUSION: Selenium or vitamin E, alone or in combination at the doses and formulations used, did not prevent prostate cancer in this population of relatively healthy men. TRIAL REGISTRATION: clinicaltrials.gov identifier: NCT00006392.