Long-term Outcomes Comparable Between Conventional vs Hypofractionated Radiation Therapy in Prostate Cancer

hypofractionated radiation therapy

Patients who received hypofractionated radiation therapy (HRT) did not demonstrate statistically significant differences in long-term outcomes compared with patients who received conventional radiation therapy (CRT), according to study results presented during a scientific session at the 2015 ASTRO Annual Meeting. Because of the comparable efficacy of various treatment options in prostate cancer, quality-of-life (QoL) outcomes have become important in decision-making. Currently, there is no long-term QoL data comparing conventional with hypofractionated radiation therapy.

“In general, hypofractionated and conventional fractionated radiation therapy have similar long-term quality-of-life outcomes,” said Talha Shaikh, MD, lead author of the study and resident in the department of radiation oncology at Fox Chase Cancer Center. Traditionally, physicians have been concerned about delivering radiation therapy to the prostate, “but advanced radiation techniques have made delivery of high-dose conformal radiation with minimal toxicity increasingly attainable,” said Shaikh.

In the phase III study, 303 men with low-to-high-risk prostate cancer received either 76 Gy in 38 fractions at 2.0 Gy per fraction (CRT) versus 70.2 Gy in 26 fractions at 2.7 Gy per fraction (HRT). The Expanded Prostate Cancer Index Composite (EPIC) survey, which measures urinary incontinence, urinary irritative/obstructive bowel, and sexual hormonal symptoms on a scale from 0 to 100; the International Prostate Symptom Score (IPSS) questionnaire, which measures frequency, nocturia, weak urinary stream, hesitancy, intermittence, incomplete emptying, and urgency on a 0 to 35 scale and QoL on a 0 to 6 scale; and the EuroQoL five-dimension Questionnaire (EQ5D), which measures mobility, self-care, usual activities, pain/discomfort, anxiety/depression and a visual analogue scale were used to assess patient reported outcomes (PRO) in the study, which followed men from 2002 through 2006. At each time point, mean PRO scores were reported. Changes from baseline, defined as the score <1 month prior to initiation of radiation therapy, were compared between treatment arms. Generalized estimating equation models were used to assess the effect of treatment over time.

The median follow-up was 69 months (range 7-136). There was no significant difference between the two cohorts regarding clinical or treatment-related characteristics. There was an initial decrease in all EPIC domains in both treatment arms although this subsequently stabilized. There was no significant difference in mean score change for the EPIC bowel (P<.01), sexual (P<.01), hormonal (P<.01), or urinary irritative/obstructive (P<.01) domains between the two treatment groups.

Patients in the HRT arm exhibited a larger decrease in score on the EPIC urinary incontinence domain at 3 years versus the CRT arm (-7.2 vs -1.3,P= .03), although this improved with further follow-up and was no longer significantly different after 5 years. There was no significant difference in overall IPSS score or QoL score between the two treatment cohorts. There was a trend toward a worse IPSS score at 2 (P= .06) and 3 years (P= .06) in the HRT group, although this improved with further follow-up.

&ldquo;Patients receiving HRT appear to have inferior genitourinary incontinence outcomes versus patients receiving CRT,&rdquo; said Shaikh. He noted that patients with poor baseline genitourinary function may have worse QoL outcomes with hypofractionated radiation versus conventionally fractionated radiation. In addition, &ldquo;baseline function is an important predictor of long-term QoL outcomes for all domains measured.&rdquo;

Moderator of the scientific session, Ronald C. Chen, MD, MPH, asked if there was a clinical difference in the proportion of patients with incontinence. &ldquo;It does appear that patients have worse GU incontinence scores, but at this time, I can&rsquo;t specify differences between the groups,&rdquo; said Shaikh.

References

1. Shaikh T, Li ME, Johnson L, et al. Long-term patient reported outcomes from a phase 3 randomized prospective trial of conventional versus hypofractionated IMRT radiation therapy for localized prostate cancer. Presented at: ASTRO 2015; October 18-21; San Antonio, TX. Abstract 77.