Acute and late toxicity after moderate hypo-fractionated intensity modulated radiotherapy (IMRT) with simultaneous integrated boost (SIB) for prostate cancer

Introduction. Moderate hypo-fractionated intensity-modulated radiotherapy with simultaneous integrated boost (MHF-IMRT SIB) aims to optimize tumor control while minimizing toxicity. This study evaluated acute and late toxicities associated with MHF-IMRT SIB in prostate cancer patients. Material and methods. Prospective cohort study included 73 patients with intermediate to very high-risk prostate cancer and nodal involvement, treated with 70 Gray (Gy) in 28 fractions using MHF-IMRT SIB. Patients were fol­lowed for 2.5 years (January 2022–December 2024). Primary endpoint was acute toxicity; secondary endpoint was late toxicity, both assessed by CTCAE v5.0. Dose-volume parameters (V40–V70) were correlated with toxicity. Results. Mean patient age was 67.6 years, most of whom had T2c disease. At 30 months follow-up, overall survival was 100%. Five patients (6.8%) experienced biochemical relapse, and two developed bone metasta­ses. During radiotherapy, G2 genitourinary (GU) toxicity was observed in 29 patients (39.7%), with G3 toxicity in seven patients (9.6%). Gastrointestinal (GI) toxicity G2 was in 26 patients (35.6%) and G3 in three patients (4.1%), toxicity peaked at week four. Within three months post-radiotherapy, G2 GU and GI toxicities were noted in 19.2% and 8.2% of patients, respectively. At the end of follow-up, chronic GU toxicity G2 was recorded in 6.8% of patients. Chronic GI toxicity G1 was recorded in 4 patients (5.5%). Dose-volume parameters (V40–V70) cor­related significantly with toxicity grades. Conclusions. MHF-IMRT to 70 Gy in 28 fractions showed a favorable toxicity profile in prostate cancer. Most acute and late genitourinary and gastrointestinal toxicities were mild and tolerated.