NSABP B-35

  • The NSABP B-35:
    • Is a phase III clinical trial:
      • That randomized postmenopausal women with ER-positive DCIS to:
        • 5 years of anastrozole or tamoxifen:
          • Following breast-conserving surgery and radiation
      • The trial sought to determine:
        • How effective anastrozole is compared to tamoxifen in preventing a breast cancer occurrence:
          • As well as the quality of life of patients taking anastrozole
    • The trial is currently closed after meeting its accrual goal of:
      • 3100 patients
    • Median follow-up of 9 years
    • Investigators found:
      • Significantly fewer breast cancer events in the anastrozole group (n = 90) than in the tamoxifen group (n = 122):
        • Hazard ratio, 0.73; confidence interval, 0.56–0.96, P=0.0234
    • The estimated 10-year breast-cancer-free interval rates were:
      • 93.5% for anastrozole versus
      • 89.2% for tamoxifen
        • This recorded difference in breast cancer-free interval:
          • Was attributable almost entirely to younger postmenopausal women:
            • Less than 60 years of age
    • Interestingly:
      • The difference between treatments did not become apparent until after 5 years of follow-up:
        • Likely due to the low number of events in both groups
    • There was no difference in overall survival (OS):
      • Between the two treatment groups