Therapies with the continuous administration of anti-hormonal agents in sex-hormone-dependent malignancies such as prostate and breast carcinomas often lead to the development of resistant tumor cells. A systematic evaluation of the use and effects of the intermittent application of endocrine therapy could provide information on the state of knowledge in this research area. PubMed, Cochrane Library, Embase, and Web of Science will be systematically searched using pretested search strategies. Randomized and non-randomized controlled trials, pragmatic trials, case-control, and comparative cohort studies will be eligible. Primary outcomes will be progression-free survival, disease-free survival, and overall survival. The literature retrieved will be selected based on predefined inclusion and exclusion criteria. Relevant data will be extracted from included references into a pre-designed table. The risk of bias will be assessed, and the report of the results will follow PRISMA recommendations and include any deviations from this protocol. The increasing prevalence of breast and prostate cancer and limitations of current therapeutic approaches require a closer look at alternatives. Additionally, to explore new therapeutic agents, modalities of administration should be rigorously reviewed to determine the best regimens for patients. This proposed systematic review aims to summarize and evaluate the current knowledge regarding intermittent endocrine cancer therapy to provide a basis for further research.
Keywords: breast cancer; endocrine therapy; intermittent administration; prostate cancer.