Prostate cancer radiotherapy regimen may not impact long-term toxicity
medwireNews: Patients with intermediate-to-high-risk localized prostate cancer report similar long-term bowel and urinary symptoms and sexual function whether treated with ultra-hypofractionated radiotherapy or conventional radiotherapy, phase 3 study data show.
However, patient-reported bowel toxicity is significantly worse immediately after ultra-hypofractionated radiotherapy than after conventional radiotherapy, report Per Fransson (Umeå University, Sweden) and co-investigators from the phase 3 HYPO-RT-PC trial.
The primary analysis from the trial found no significant difference in the rates of 5-year failure-free survival and physician-assessed toxicity between ultra-hypofractionation, given at a dose of 42.7 Gy in seven fractions, 3 days per week for 2.5 weeks, and conventional fractionation, given as 78.0 Gy in 39 fractions, 5 days per week for 8.0 weeks.
However, Fransson and colleagues note that “physician-reported ratings of symptoms do not necessarily correlate well with PROs [patient-reported outcomes]” and PROs can therefore “be an important guide in the choice of treatment,” particularly because “toxicity is a common concern for patients.”
The current analysis included data for 1165 participants, with a median 48 months of follow-up, who completed the Prostate Cancer Symptom Scale (PCSS) and the 30-item EORTC Quality-of-Life Questionnaire (EORTC QLQ-C30) at baseline, the end of radiotherapy, and at regular intervals throughout the study follow-up.
On the PCSS, there was no significant difference in the incidence of clinically relevant deterioration (change of ≥0.5 points from baseline) in the majority of individual urinary symptoms between the two treatment arms at each timepoint up to 6 years. There was also no difference at 6 years in the rate of self-reported clinically relevant deterioration of overall bother from all urinary problems, at 28% among 120 patients with data in the ultra-hypofractionation group and 33% of 132 patients in the conventional fractionation group.
By contrast, the researchers found that, compared with conventional radiotherapy, a significantly higher proportion of patients who received ultra-hypofractionation reported clinically relevant deteriorations immediately after radiotherapy in seven of the 10 bowel symptoms assessed, namely stool frequency, rush to toilet, flatulence, bowel cramp, mucus, blood in stool, and limitation in daily activity.
However, by 3 months, there were no significant differences in bowel symptoms between the two groups, and at 6 years, 28% of 123 patients in the ultra-hypofractionation group and 33% of 129 patients in the conventional fractionation group reported clinically relevant deterioration in overall bother from all bowel symptoms.
There was no clinically relevant deterioration in overall sexual bother in either group and no significant difference between the two groups throughout the course of the study.
The QLQ-C30 showed significantly higher rates of clinically relevant deterioration (≥5 points from baseline) at the end of ultra-hypofractionated radiotherapy than after conventional radiotherapy fractionation for role function, emotional function, global health/quality of life (QoL), pain, and diarrhea, but there were no significant differences thereafter.
At 6 years, 37% of 125 patients in the ultra-hypofractionation group and 42% of 134 patients in the conventional fractionation group reported clinically relevant deterioration of global health/QoL.
Writing in The Lancet Oncology, Fransson and co-authors say their study “adds to the growing evidence for ultra-hypofractionated radiotherapy becoming standard treatment for intermediate- to-high-risk prostate cancer.”
They note, however, that “further long-term studies are needed” to confirm their findings and also point out that a cost-effectiveness study on the HYPO-RT-PC data is underway.
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