Effect of Conventional Chemotherapy in Patients With Neuroendocrine Tumours: A Systematic Review

Background: Neuroendocrine tumours (NETs) are a wide-ranging group of neoplasms originating from neuroendocrine cells. In 2014 NETs incidence was 7 per 100000 people annually. The purpose of this systematic review is to evaluate the safety and efficacy of various types of chemotherapeutic agents on gastroenteropancreatic NETs (GEP NETs) and to determine which type of chemotherapy is the most effective for different tumour types, with minimum adverse events. To our knowledge, this study is the first systematic review that compares several types of chemotherapy and evaluates their safety and efficacy on GEP NETs. Methods: The study followed recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines on reporting systematic reviews. The literature search for this systematic review was conducted using the following databases and search engines: Cochrane library, EMBASE, Google Scholar, PubMed, and Web of Science, from 1963 to 2020. Results: The review comprised 26 observational studies, and 5 randomized controlled trials (RCTs). The total number of subjects included in this study was 1783. Our study showed that the most effective treatment for Grade 3 NETs and Grade 3 neuroendocrine carcinomas was cisplatin/etoposide. Furthermore, capecitabin/temozolomide therapy has been shown to be most effective in Grade 1 and Grade 2 NETs. Conclusion: Therapy with two chemotherapeutic agents has been shown to be more effective than monotherapy and therapy with three chemotherapeutic agents. Unfortunately, our study has limitations and we urgently need RCTs or larger observational studies that will contain all the necessary efficacy and safety tools, and thus provide answers to our clinical questions.