BACKGROUND:Biologics are widely used to manage the side effects of cancer treatment (e.g., epoetin alfa is used to treat chemotherapy-induced anemia [CIA] and granulocyte colony-stimulating factors [G-CSFs] are used to treat chemotherapy-induced neutropenia [CIN]). As several patents for biologics used in cancer treatment have expired, a number of companies have developed supportive care biosimilars (e.g., epoetin alfa biosimilar, filgrastim biosimilar, pegfilgrastim biosimilar). OBJECTIVE:The objective of this study was to synthesize current evidence on the efficacy and safety of supportive care biosimilars compared with their reference biologics in oncology. METHODS:We searched PubMed, Embase, the Cochrane library, ClinicalTrials.gov, ISI Web of Science and several Chinese databases from their inception dates to December 31, 2018 for randomized controlled trials (RCTs) or comparative observational studies that compared the efficacy and safety of supportive care biosimilars and their reference biologics in oncology. We pooled results separately for RCTs and observational studies, as such studies involve different patient populations and are designed differently. We pooled binary outcomes using risk ratios (RR) with confidence intervals (CIs) and continuous outcomes using weighted mean differences (WMD) with 95% CIs, then conducted subgroup and sensitivity analyses. We used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach to rate the quality of evidence. RESULTS:We identified 28 studies that compared biosimilars of G-CSF or epoetin alfa: one RCT and five cohort studies (total N = 2816) of epoetin alfa biosimilars, and 13 RCTs and 9 cohort studies (total N = 23,043) of G-CSF biosimilars [corrected]. Despite involving different populations, RCTs and observational studies comparing biosimilars and reference biologics indicated similar efficacy and safety results. Overall, there was no statistically significant difference in any efficacy or safety outcomes between any biosimilars and their corresponding original biologics (all p > 0.05). The quality of GRADE evidence of efficacy and safety outcomes was moderate or low. Findings were robust for all prespecified subgroup and sensitivity analyses. CONCLUSION:Existing evidence suggests highly comparable efficacy and safety profiles for supportive care biosimilars and their reference biologics in oncology.