Table 2.

Studies relating duration of and/or adherence to adjuvant endocrine therapy to breast cancer outcome

Lead authorStudyFindings
EBCTCG—Early Breast Cancer Trialist Collaborative Group 2001Overview analyses of randomized clinical trials evaluating duration of tamoxifen useTamoxifen duration 1 year, recurrence reduced 27%; tamoxifen duration 2 years, recurrence reduced 33%; tamoxifen duration 5 years, recurrence reduced 47%; P trend < 0.00001
Yood et al. (29)Cohort of 1,837 U.S. patients (≥65 years old) with early-stage breast cancerAdjuvant tamoxifen <1 year vs. ≥ 5 years with higher breast cancer mortality (HR, 6.26; 95% CI, 3.10–12.64)
McCowan et al. (30)Retrospective cohort of 2,080 Scottish patients with early-stage breast cancerAdherence to tamoxifen <80% associated with poorer survival (HR, 1.10; 95% CI, 1.001–1.21)
Hershman et al. (23)Northern California Kaiser Permanente cohort of 8,769 women with early-stage, hormone-sensitive breast cancer and endocrine therapy adherence (drug availability)31% discontinued therapy, 10-year survival was 73.6% 69% continued therapy, 10-year survival was 80.7%; P < 0.001
Xu et al. (37)Cohort of 116 men with early-stage, hormone-sensitive breast cancer and hormone therapy adherenceFor those adherent, 10-year survival was 79.6%; for those nonadherent, 10-year survival was 50.5%; P = 0.008
Markkula et al. (34)Prospective cohort of 417 Swedish patients with early-stage breast cancer and adherence (self-report) to adjuvant endocrine therapyNonadherence at the 1-year visit associated with increased early breast cancer events (HR, 2.97; 95% CI, 1.08–8.15)
Haque et al. (32)Southern California Kaiser Permanente cohort of 22,850 women with early-stage breast cancer and endocrine therapy adherence (drug availability)Women with high adherence had greater recurrence risk reduction (e.g., HR, 0.42; 95% CI, 0.36–0.47 for tamoxifen) compared with those with less adherence (HR, 0.46; 95% CI, 0.41–0.52 for tamoxifen) but the difference was not statistically significant.
Pagani et al. (36)International Breast Cancer Study Group trials 13–93 and 14–93 with 690 women with early-stage breast cancer or SERMsWomen with ≥4 years of SERM had longer 10-year disease-free survival (71%) compared with <4-year use (64%), P = 0.20