Comparison of Toxicity between Single Modality Radiation Therapy and Combined Modality Radiation Therapy among Early Stage Prostate Cancer Patients Open Access

Abstract

Background: For early stage prostate cancer, conservative management is generally considered appropriate as most of these cancers are quite slow growing in nature. Aggressive therapy is sometimes used in the management of early stage disease but needs to be evaluated in the context of health related quality of life and post-treatment morbidity. This study aims to compare radiation related toxicities (gastrointestinal, genitourinary, sexual function) for early stage prostate cancer patients over the age of 65 who were treated with either a more conservative single modality or a more aggressive multimodality radiation therapy approach.

Methods: A population-based cohort study was conducted using Surveillance, Epidemiology and End Result (SEER) data linked to Medicare data. Cumulative incidence was used to calculate the probability of each outcome event of interest (toxicity).Multivariate logistic regression models were used to adjust potential confounders and assess interaction while exploring the relationship between treatment and outcomes.

Result: The final cohort of 9,202 patients consisted of 4,567patientstreated with external beam radiation only, 3,039 patients treated with brachytherapy alone, and 1,596 patients treated with combined modality radiation treatment of both external radiation and brachytherapy. Generally, patients treated with combined modality radiation therapy tended to be slightly younger, with a higher T stage, higher Gleason Score and a larger number of existing comorbidities. Among the 9 toxicity events evaluated in this study, the most frequent radiation related toxicity events were GU Incontinence (38.31%), Erectile Dysfunction (23.36%) and GU Obstruction (16.59%). The least frequent event was GU Fistula (0.07%).A significant protective effect (OR<1) of external beam radiation only compared to combined modality therapy was found for GI Fistula, GU Cystitis and Erectile Dysfunction. Significant protective effects (OR<1) for both external beam radiation therapy alone and brachytherapy alone, compared to combined modality radiation therapy, were found in models for GU Incontinence and GU Obstruction. Conclusions: Decisions regarding the use of combined modality radiation therapy to treat low risk, clinically localized prostate cancer patients should be carefully made by health providers in conjunction with their patients considering both the high survival rate of disease in these patients and the increased risk in multiple radiation related toxicity events.

Table of Contents

Table of Contents

Background...1 Methods...2 Results...6 Discussion...7 Strengths& Weaknesses...9 Conclusions...10 References...10 Tables...13 Appendix...17

About this Master's Thesis

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School	Rollins School of Public Health
Department	Epidemiology
Degree	MPH
Submission	Master's Thesis
Language	English
Research Field	Health Sciences, Public Health Health Sciences, Epidemiology Health Sciences, Radiology
Keyword	Toxicity Radiation Prostate Cancer
Committee Chair / Thesis Advisor	Ward, Kevin C., Emory University
Committee Members	Canter, Daniel J, Emory University
Partnering Agencies	Emory University schools, faculty or affiliated programs Hospital or other health care provider

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