Evaluation of the effect of metformin as a radiosensitiser in solid tumours: A systematic review.

Background: Metformin is an antidiabetic drug that has shown its benefit in increasing the effect of radiotherapy in the treatment of solid tumors in preclinical studies. The objective of this systematic review is to study the effect of metformin as a radiosensitizer in studies carried out in clinical practice.

Methods: Systematic review carried out according to PRISMA criteria of clinical trials, systematic reviews and observational studies focused on the influence of metformin as a radiosensitizer in solid tumors. The studies were published between the years 2010 and 2022. The results of the studies have been analyzed in terms of survival (OS, PFS, DFS, DMFS) and response (ORR) between patients treated with metformin and without it.

Results: A total of 16 studies have been found in the literature (the most frequent tumor was prostate cancer, 5 studies). External radiotherapy was administered in all the studies and in two of them to greater brachytherapy. The use of metformin with radiotherapy showed a consistent benefit in terms of survival and response in tumors of prostate, hepatic and gynecological origin. The benefit in the rest of the tumors analyzed (lung, rectal, and head and neck cancer) is doubtful, and the results are contradictory. The greatest benefits were observed in prostate tumors both in OS and SLE.

Conclusions: The use of metformin in combination with radiotherapy in solid tumors is one of the most promising treatments under development in oncology. The benefit observed in real-life studies makes it necessary to develop clinical trials that specifically evaluate its use in clinical practice in the future.