Larger Prostates Showed Post-Radiotherapy Urinary Symptom Normalization

At the 2026 American Society for Radiation Oncology (ASTRO) Annual Meeting, Allen Khodab, MD, discussed how patients with larger prostates experienced International Prostate Symptom Scores (IPSS) score reductions that normalized to the same level as those with normal-sized glands; a finding that exceeded initial expectations and offers a new data point for clinicians counseling patients ahead of treatment.

In an interview with CancerNetwork®, Khodab discussed results from a retrospective study evaluating whether prostate volume influenced urinary quality of life after external beam radiation therapy. The initial hypothesis aligned with existing literature linking prostates larger than 60 cc to elevated toxicity risk and assumed greater dose exposure to surrounding structures such as the lower urethra and trigone of the bladder would sustain higher IPSS scores. However, IPSS scores in the larger-prostate cohort instead normalized to the same level as the normal-sized group by final follow-up, a finding Khodab attributed to obstruction relief and radiation-induced gland shrinkage. He acknowledged the inherent limits of the retrospective design, which spanned 2004 to 2019, while noting that the cohort size lends the result clinical utility for patient counseling.

Khodab is an incoming resident specializing in radiation oncology at University of Miami Sylvester Cancer Center.

Transcript:

CancerNetwork: Going in, was the hypothesis that larger prostates would predict worse urinary quality of life after radiation? How do the actual results compare to what you expected?

Khodab: The initial hypothesis was that we figured that the IPSS scores would be higher for the larger prostate group, which made sense because of the mechanical obstruction aspect. But we didn’t think that the IPSS scores would respond as much because the other factor is that, for larger prostates, there’s more dose delivered to the surrounding structures—the lower urethra and the trigone of the bladder. We didn’t really expect the IPSS scores to decrease as substantially as they did, but they normalize to about the level that we found in the normal-size cohort.

Some of the limitations: this study ran from 2004 to 2019, and prostate cancer treatment has evolved so much over that time. Although all patients were treated with external beam [radiation] without any brachytherapy, treatment modalities have changed, technology has changed, and there were different radiation oncologists doing the plans, which are variables we can’t really control for in a retrospective study. In a prospective study, we could control for a lot more of these variables and be more consistent, but that’s a natural limitation of the study design we chose, and it’s also what allowed us to have as large a cohort as we did.

Reference

Khodab A, Kacker S, Song D, et al. Determining the effect of prostate size on the quality-of-life outcomes for prostate cancer patients undergoing definitive radiotherapy. Presented at: 2026 American Society for Radiation Oncology (ASTRO) Annual Meeting; October 2026. Abstract 3294