The Effectiveness And Toxicity Of Adjuvant Endocrine Therapy For Early Breast Cancer: A Meta-analysis

Objective:Adjuvant endocrine therapy is the standard of women with oestrogen receptor(ER)-positive early breast cancer,treatment with endocrine substantially reduces the breast cancer recurernce rate and mortality rate.Hormone receptor expressing breast caners are characterized by the propensity for late recurrence.The effect of extended adjuvant endocrine therapy remains unclear.The purpose of this study was to compare the efficacy of continued adjuvant endocrine therapy(>5 years)with stopped adjuvant endocrine therapy(5 years).Methods:The PUBMED,MEDLINE,EMBASE databases were systematically reviewed to identify clinical trials published up to November 2015.Online abstracts from the proceedings of the Annual Meetings of the American Society of Clinical Oncology(ASCO)(1993-2015)was also reviewed.Primary endpoints included breast cancer recurrence rate and breast cancer death rate,then while secondary endpoints included the incidence of endometrial carcinoma and the incidence rate of bone events reported as odds ratios(ORs)and 95 % confidence interval(CI).Results: Eight trials,including the experimental group(extended endocrine therapy group)14,551 and control group(stop treatment group)14608.Extended adjuvant endocrine therapy was associated with a significant reduction in the risk of recurrence(OR:0.85;95% CI,0.79-0.91;p<0.001).There was no association between extended adjuvant endocrine therapy and all-cause death(OR,0.95;95%CI,0.90-1.01;p=0.14).While endometrial carcinoma was substantially more frequent with extended adjuvant tamoxifen(OR,1.99;95%CI,1.60-2.48;p<0.001).Longer duration of aromatase inhibitor use was associated with increased odds of developing bone fractures(OR,1.23;95%CI,1.02-1.49;p<0.001).Subgroup analysis was performed in the experimental group,and divided into the tamoxifen group aromatase inhibitor group.Subgroup analysis suggested that extended adjuvant aromatase inhibitor was an apparent reduction in risk of recurrence compared with extended adjuvant tamoxifen(OR= 0.88;95%CI,0.82-0.95 VS OR= 0.63;95%CI,0.50-0.78).Subgroup analysis suggested that lymph node positive patients who are more benefit from extended adjuvant endocrine therapy compared with those who are lymph node negative.Subgroup analysis suggested that in ER(+)breast cancer,extended endocrine therapy significantly reduced mortality.Conclusion:(1)In unselected patients,extended adjuvant endocrine therapy is associated with a significant reduction in recurrence,but not associated with a reduction in all-cause death.(2)Subgroup analysis showed that lymph node positive patients in reducing the recurrence of breast cancer especially benefit from extended adjuvant endocrine therapy.(3)Subgroup analysis showed that ER(+)patients in reducing breast cancer mortality benefit from extended adjuvant endocrine therapy.