Breast cancer survivorship: state of the science

Only recently has breast cancer survivorship earned formal recognition as a research discipline. Complicating survivorship research is the frequent overlap between aging and treatment sequelae. The ACS/ASCO 2016 Breast Cancer Survivorship Care Guideline (Guideline) reflects comprehensive literature review through April 2015, while the jointly sponsored, inaugural Cancer Survivorship Symposium in 2016 (Symposium) reflects ongoing research activity in the area. Together, these platforms provide an opportunity to examine the use of randomized trials and controlled studies in survivorship care research. All 236 citations from the Guideline and all 250 abstracts from the Symposium were reviewed independently by two authors and assigned to prospectively determined categories. Guideline citations were most frequently reviews (n = 88, 37.3%) and non-randomized, non-controlled studies (n = 51, 21.6%). Thirty-seven (15.7%) randomized trials were cited. Only 9% of Guideline recommendations were based on randomized clinical trial evidence, while 64% were based on evidence level "0" (expert opinion, clinical practice, etc.). Symposium abstracts consisted largely of non-randomized, non-controlled studies (n = 113, 45.2%), with ten completed randomized trials (4%). Few Guideline citations or Symposium abstracts incorporated matched, cancer-free controls. Based on the literature underlying the ASCO Guideline as well as a survey of the Cancer Survivorship Symposium abstracts, a significant proportion of the survivorship literature at least through 2015 consisted of non-randomized, non-controlled studies. To optimally address survivorship issues, cancer therapy sequelae need to be distinguished from normal aging in studies incorporating cancer-free controls, and randomized clinical trials are needed to inform intervention strategies.