Radiotherapy-related toxicity for localized prostate cancer: meta-analysis comparing conventional or moderately hypofractionated vs. ultrahypofractionated protocols

Background To compare toxicities in relation to standard radiation treatments [conventional fractionation RT (CRT) and moderate hypofractionated RT (MRT)] with ultrahypofractionated RT (URT) in the treatment of patients with localized PCa. Methods A searched was performed in Medline, Embase, Cochrane CENTRAL, and LILACS to January 2020 for studies comparing URT to CRT and/or MRT in relation to genitourinary (GU) and gastrointestinal (GI) toxicity in the treatment of patients with localized PCa. URT, MRT and CRT were defined as protocols delivering a daily dose of >= 5 Gy, 2.4-4.9 Gy, and <2.4 Gy per fractions regardless total dose, respectively. Results Eight studies with 2929 patients with localized PCa were included in the analysis. These eight studies did not find any difference between URT and MRT/CRT groups in relation to acute GU toxicity (21.0% x 23.8%, RD -0.04; 95% CI -0.13, 0.06; p = 0.46; I-2 = 89%) and acute GI toxicity (4.9% x 6.9%, RD -0.03; 95% CI -0.07, 0.01; p = 0.21; I-2 = 79%). Six studies did not find any difference between URT and MRT/CRT groups in relation to late GU toxicity (3.9% x 4.7%, RD -0.01; 95% CI -0.03, 0.00; p = 0.16; I-2 = 19%) and late GI toxicity (2.1% x 3.5%, RD -0.01; 95% CI -0.03, 0.00; p = 0.05; I-2 = 22%). Conclusion The present study suggests that acute GU/GI and late GU/GI toxicity are similar between URT and standard protocols. More studies with longer follow-ups directed to oncology outcomes are warranted before any recommendation on this topic.