Moderately Hypofractionated Helical Tomotherapy for Prostate Cancer: Ten-year Experience of a Mono-institutional Series of 415 Patients

Abstract

Background/Aim: Radiotherapy represents an important therapeutic option in the management of prostate cancer (PCa). As helical tomotherapy may improve toxicity outcomes, we aimed to evaluate and report the toxicity and clinical outcomes of localized PCa patients treated with moderately hypofractionated helical tomotherapy. Patients and Methods: We retrospectively analyzed 415 patients affected by localized PCa and treated with moderately hypofractionated helical tomotherapy in our department from January 2008 to December 2020. All patients were stratified according to the D'Amico risk classification: low-risk 21%, favorable intermediate-risk 16%, unfavorable intermediate-risk 30.4%, and high-risk 32.6%. The dose prescription for high-risk patients was 72.8 Gy to the prostate (planning tumor volume-PTV1), 61.6 Gy to the seminal vesicles (PTV2), and 50.4 Gy to the pelvic lymph nodes (PTV3) in 28 fractions; for low-and intermediate-risk patients 70 Gy for PTV1, 56 Gy for PTV2, and 50.4 Gy for PTV3 in 28 fractions. Image-guided radiation therapy was performed daily in all patients by mega-voltage computed tomography. Forty-one percent of patients received androgen deprivation therapy (ADT). Acute and late toxicity was assessed according to the National Cancer Institute's Common Terminology Criteria for Adverse Events v.5.0 (CTCAE). Results: Median follow-up was 82.7 months (range=12-157 months) and the median age of patients at diagnosis was 72.5 years (range=49-84 years). The 3, 5, and 7 yr overall survival (OS) rates were 95%, 90%, and 84%, respectively, while 3, 5, and 7 yr disease-free survival (DFS) were 96%, 90%, and 87%, respectively. Acute toxicity was as follows: genitourinary (GU) G1 and G2 in 35.9% and 24%; gastrointestinal (GI) in 13.7% and 8%, with G3 or more acute toxicities less than 1%. The late GI toxicity G2 and G3 were 5.3% and 1%, respectively, and the late GU toxicity G2 and G3 were 4.8% and 2.1%, respectively, and only three patients had a G4 toxicity. Conclusion: Hypofractionated helical tomotherapy for PCa treatment appeared to be safe and reliable, with favorable acute and late toxicity rates and encouraging results in terms of disease control.External beam radiotherapy is a milestone in the treatment of men with prostate cancer (PCa) with curative intent and is associated with long-term disease control in most patients (1). Historically, the standard radiotherapy treatment involves conventional fractionation, with doses of 1.8-2 Gy/day, treatment approximately over 7 weeks, with onerous costs and a negative impact on the patient's quality of life (2, 3). Over the last decade, the constant improvement in radiotherapy techniques, including intensity-modulated radiotherapy (IMRT) and image-guided radiotherapy (IGRT), has led to more personalized treatment, with the possibility of using doseescalated schedules with significant advantages in terms of biochemical control rates and cost-effectiveness (5, 6). Helical tomotherapy, with a combination of linear accelerator and computed tomography chara...