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. Author manuscript; available in PMC: 2016 Oct 1.
Published in final edited form as: Semin Oncol. 2015 Jul 10;42(5):748–763. doi: 10.1053/j.seminoncol.2015.07.006

Table 2.

Summary of Results of Large-Scale Prevention Trials

Study Name NCT Identifier Sponsoring Organization Intervention Study Size Time of Accrual Results
Prostate Cancer Prevention Trial (PCPT) Southwest Oncology Group (SWOG)
http://swog.org 		Finasteride vs. Placebo with serial PSA screening and end-of-study biopsy 18,882 men age 55+ randomized from January 1994 to May 1997 Men taking finasteride had 25% fewer prostate cancers, but seemed to have a slightly higher incidence of aggressive tumors. Further pathological analysis and data have shown that reduced prostate size contributes to finding more high-grade tumors.
Selenium and Vitamin E Cancer Prevention Trial (SELECT) NCT00006392 Southwest Oncology Group (SWOG)
http://swog.org 		Selenium vs. Vitamin E vs. both vs. placebos in men 35,543 men age 55+ (50+ for African Americans) August 2001 to June 2004 Neither selenium nor Vitamin E separately or together prevented the development of prostate cancer. On follow-up, men who took vitamin E alone had a 17 percent relative increase in numbers of prostate cancers compared to men on placebo.
Breast Cancer Prevention Trial (BCPT) National Surgical Adjuvant Breast and Bowel Project (NSABP), now part of NRG Oncology
http://nsabp.pitt.edu 		Tamoxifen vs. Placebo in women at increased risk of breast cancer 13,388 women ages 35+ accrued April 1992 to May 1997 Women taking tamoxifen had 49% fewer diagnoses of invasive and noninvasive breast cancers, as well as increased risk of blood clots and uterine cancers. Tamoxifen approved by U.S. Food and Drug Administration (FDA) in 1998 for reduction of breast cancer risk in women at increased risk.
Study of Tamoxifen and Raloxifine (STAR) (breast) NCT00003906 National Surgical Adjuvant Breast and Bowel Project (NSABP), now part of NRG Oncology
http://nsabp.pitt.edu 		Tamoxifen vs. Raloxifene in postmenopausal women at increased risk of breast cancer 19,747 women age 35+ accrued from July 1999 to November 2004 Raloxifene found equivalent to tamoxifen for reducing invasive breast cancer risk with reduced risk of blood clots and uterine cancers; follow-up showed raloxifene reduced risk of noninvasive breast cancer. Raloxifene approved by FDA in 2007 for reduction of breast cancer risk in postmenopausal women at increased risk.