NSABP B-20 — National Surgical Adjuvant Breast and Bowel Project Protocol B-20

Phase 3 · 1997 · Breast Cancer

Design

Randomized phase 3 trial comparing tamoxifen alone versus tamoxifen plus chemotherapy (CMF or MF) in women with node-negative, estrogen-receptor-positive breast cancer.

Population

Women with lymph node-negative, estrogen receptor-positive operable breast cancer.

Primary Endpoint

Disease-free survival

Key Result

Adding chemotherapy to tamoxifen improved 5-year disease-free survival to 90% with MF plus tamoxifen and 89% with CMF plus tamoxifen versus 85% with tamoxifen alone (RR of recurrence 0.68 for MF-T and 0.62 for CMF-T).

Guideline Impact

Supported chemoendocrine therapy in node-negative ER+ disease and enabled Oncotype DX validation