Second malignancy probabilities in prostate cancer patients treated with SBRT and other contemporary radiation techniques. (August 2021)

• Record Type: Journal Article
• Authors: Dee, Edward Christopher; Muralidhar, Vinayak; King, Martin T.; Martin, Neil E.; D'Amico, Anthony V.; Mouw, Kent W.; Orio, Peter F.; Nguyen, Paul L.; Leeman, Jonathan E.
• Is Part Of: Radiotherapy and oncology. Volume 161(2021)
• Page Start: 241
• Page End: 250
• Publication Date: 2021-08
• Subjects: Prostate cancer -- SBRT -- External beam radiation therapy -- Prostate radiotherapy -- Secondary malignancy; Oncology -- Periodicals; Radiotherapy -- Periodicals; Tumors -- Periodicals; Medical Oncology -- Periodicals; Neoplasms -- radiotherapy -- Periodicals; Radiotherapy -- Periodicals; Radiothérapie -- Périodiques; Cancérologie -- Périodiques; Tumeurs -- Périodiques; Electronic journals; 616.9940642
• DOI: 10.1016/j.radonc.2021.06.023
• Languages: English
• ISSNs: 0167-8140

Abstract

Highlights: Risk of second malignancy (SM) with hypofractionated prostate RT or SBRT is unknown. Probabilities of SM after prostate cancer treatments were derived from NCDB. Probability of SM was similar between SBRT and radical prostatectomy. Probability of SM was lower with SBRT compared to other radiation modalities. Abstract: Background: Prostate radiotherapy has been associated with an increased risk of developing a second malignancy (SM). However, relative SM probabilities following treatment with contemporary radiation techniques such as stereotactic body radiotherapy (SBRT) or moderately hypofractionated intensity modulated radiotherapy (HF-IMRT) remain unknown. Methods: A cohort analysis was performed of men from a nationally representative database with localized prostate cancer with at least 60 months of follow-up comparing SM probability amongst men receiving either radical prostatectomy (RP), conventionally fractionated intensity-modulated radiotherapy (CF-IMRT), HF-IMRT, brachytherapy (BT), or SBRT, using multivariable logistic models, which were used to generate predicted probabilities. Additionally, propensity score-adjusted pairwise assessments of modalities were performed. Results: For 303, 432 patients included in the study, median follow-up was 9.08 years (IQR 7.01–11.21). Predicted rates of SM by treatment modality and adjusted odds ratios (AOR) for development of SM (referent: RP) were: 6.0% for RP (AOR n/a), 7.1% for CF-IMRT (AOR 1.20, 95%CI 1.14–1.25, P < 0.001), 7.3% for HF-IMRT (AOR 1.25, 95%CI 1.01–1.55, P = 0.045), 6.6% for BT (AOR 1.11, 95%CI 1.07–1.16, P < 0.001), and 5.7% for SBRT (AOR 0.95, 95%CI 0.81–1.12, P = 0.567). On propensity score-adjusted analysis, SBRT was associated with lower odds of SM compared to CF-IMRT (AOR 0.78, 95%CI 0.66–0.93, P = 0.005); no significant difference was found when SBRT was compared to RP (AOR 0.86, 95%CI 0.73–1.03, P = 0.102). Conclusions: Conventionally fractionated intensity-modulated radiotherapy, moderately hypofractionated intensity-modulated radiotherapy, and brachytherapy but not stereotactic body radiotherapy were associated with increased probability of a second malignancy compared to radical prostatectomy. Patients treated with SBRT may be at lower risk of second malignancy due to improved conformality, radiobiological differences or patient selection. The possibility that SBRT in select patients may minimize the probability of SM underscores the need for assessment of second malignancy risk in prospective studies of SBRT.