Figure 2. Summarized results for the longevity of the effect of bisphosphonates on breast cancer survival. (A) The natural history of breast cancer after diagnosis, presented as green arrow; (B) The procedure of RCT presented as blue arrow, and golden arrow represents the duration of adjuvant treatment with bisphosphonates; (C) The results from conventional subgroup analyses by follow-up duration; (D) The results from trial sequential analyses of each subgroup by follow-up duration. *Data regarding the relapse rate of breast cancer were obtained from the Surveillance, Epidemiology, and End Results (SEER) program of the National Cancer Institute (Cheng et al. 2012). Abbreviations: ACSS, the actually cumulative sample size; BCa, breast cancer; BPs, bisphosphonates; D2-RIS, the diversity adjusted required information size; RCT, randomized controlled trial; RR, hazard ratio; TSA, trial sequential analysis.