NSABP B-57 Trial Information
Based on the available evidence, there is no NSABP B-57 trial documented in breast cancer literature. The evidence provided references multiple NSABP trials (B-13, B-14, B-33, B-35, B-42) but does not include any trial designated as B-57 1.
Documented NSABP Breast Cancer Trials
The National Surgical Adjuvant Breast and Bowel Project has conducted several landmark trials for hormone receptor-positive breast cancer, but B-57 is not among them:
NSABP B-33
- Extended adjuvant exemestane trial comparing 5 years of exemestane versus placebo after completing 5 years of tamoxifen 2
- Enrolled 1,598 postmenopausal patients with T1-3N1M0 breast cancer who were disease-free after 5 years of tamoxifen 2
- Median follow-up of 30 months showed borderline statistically significant improvement in 4-year disease-free survival (91% vs 89%; RR = 0.68; P = .07) 2
- Trial was terminated early due to NCIC MA.17 results showing benefit from extended letrozole therapy 2
NSABP B-35
- Anastrozole versus tamoxifen for ductal carcinoma in situ (DCIS) in postmenopausal women undergoing lumpectomy plus radiotherapy 3
- Enrolled 3,104 patients between 2003-2006, randomly assigned to tamoxifen 20 mg daily or anastrozole 1 mg daily for 5 years 3
- Median follow-up of 9.0 years showed anastrozole provided significant improvement in breast cancer-free interval (HR 0.73,95% CI 0.56-0.96, p=0.0234) 3
- Benefit was primarily in women younger than 60 years of age (significant treatment-by-age interaction, p=0.0379) 3
NSABP B-42
- Extended letrozole therapy trial (also known as NRG Oncology/NSABP B-42) evaluating 5 additional years of letrozole versus placebo after completing 5 years of aromatase inhibitor-based therapy 4
- Enrolled 3,966 postmenopausal patients with stage I-IIIA hormone receptor-positive breast cancer between 2006-2010 4
- Ten-year results showed statistically significant improvement in disease-free survival (HR = 0.85,95% CI 0.74-0.96; P = .01; absolute difference = 3.3%) 4
- No difference in overall survival (HR = 0.97,95% CI 0.82-1.15; P = .74) 4
NSABP B-13 and B-14
- B-13: Evaluated methotrexate and fluorouracil in 737 women with ER-negative, node-negative tumors, showing 27% reduction in treatment failure through 5 years 5
- B-14: Compared tamoxifen versus placebo in 2,844 patients with ER-positive, node-negative tumors, showing 36% reduction in treatment failure through 5 years 5
Clinical Context for the Patient Described
For a 66-year-old postmenopausal woman with hormone receptor-positive (ER 80%, PR 30%) breast cancer, the relevant evidence-based recommendations are:
- Standard adjuvant endocrine therapy should be an aromatase inhibitor (anastrozole, letrozole, or exemestane) for 5 years as initial therapy 6, 7, 8
- Extended therapy up to 10 years total should be offered if node-positive disease is present 7, 8, 4
- If aromatase inhibitor intolerance develops, switching to an alternative aromatase inhibitor is recommended before considering tamoxifen 6