Abstract
ObjectivesThe relationship between obesity (Body Mass Index >30 kg/m2) and quality of life (QoL) following prostate cancer (PCa) radiation therapy (RT) is unknown. Excess abdominal fat may compromise the precise delivery of radiation, putting surrounding organs at risk for greater radiation exposure. Stereotactic body radiation therapy (SBRT) utilizes a real-time tracking system that provides updated prostate position information and allows for correction of the therapeutic beam during treatment with high accuracy. In this study, we evaluate the impact of obesity on patient reported outcomes following SBRT for prostate cancer.Materials and methodsBetween February 2008 and April 2012, 88 obese and 178 non-obese patients with PCa were treated with SBRT at Georgetown University Hospital, Washington, DC. Health-related quality of life (HRQol) was assessed via the expanded prostate cancer index composite (EPIC)-26 at baseline, 6, 12, 18, and 24 months after 5-fraction delivery of 35-36.25 Gy with the CyberKnife. Patients who received androgen deprivation therapy (ADT) were excluded from this analysis due to its known negative impact on HRQoL.ResultsPretreatment characteristics of obese and non-obese patient groups were similar except that obese patients had lower total testosterone levels. Urinary and bowel function and bother scores between the two patient cohorts were comparable at baseline and subsequent follow-ups. Sexual function and bother were also similar at baseline between both groups. Bother was defined by displeasure patients may experience from functional decline. At 24 months post-SBRT, obese men experienced borderline clinically significant decrease in sexual function and greater sexual bother compared to non-obese patients. Fatigue was significantly higher in obese patients compared to non-obese patients at 18 months post-SBRT.ConclusionsProstate SBRT affects obese and non-obese patients similarly in total HRQoL scores and majority of its domains. Obesity has been associated with cancer recurrence; therefore longer follow-up is required to determine the impact of obesity on cancer control.
Highlights
Obesity (Body Mass Index (BMI) > 30 kg/m2) and associated poor health-related quality of life (HRQoL) affect nearly one-third of American men over 60 years old [1]
At 24 months postSBRT, obese men experienced borderline clinically significant decrease in sexual function and greater sexual bother compared to non-obese patients
Fatigue was significantly higher in obese patients compared to non-obese patients at 18 months post-Stereotactic body radiation therapy (SBRT)
Summary
Obesity (Body Mass Index (BMI) > 30 kg/m2) and associated poor health-related quality of life (HRQoL) affect nearly one-third of American men over 60 years old [1]. HRQoL in cancer patients is dynamic and may be adversely impacted by obesity. Total serum testosterone levels are inversely associated with BMI [3], and low levels may contribute to greater incidences of fatigue in obese patients [4]. Due to inherent technical difficulties associated with increased abdominal adipose tissue distribution, such as setup inconsistencies and increased prostatic movement during treatment [8], obesity can have a negative impact on PCa radiation therapy (RT) outcomes, with obese patients experiencing higher rates of biochemical recurrence and PCa specific mortality [9]. Obesity may have a negative impact on post-RT HRQoL, due to greater radiation exposure to the rectum, bladder, and sexual organs [12,13]
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