ESTRO 2024 - Abstract Book

S2604

Clinical - Urology

ESTRO 2024

Here we present long-term 7-year outcomes and the quality of life data from a phase I/II study of once-weekly ultra hypofractionated radiotherapy for non-metastatic prostate cancer patients belonging to all risk groups (NCT03518853).

Material/Methods:

Thirty patients with non-metastatic prostate cancer belonging to all risk groups were treated in a prospective phase I/II trial between Dec 2013 and Jan 2016 to test the feasibility and efficacy of once-weekly ultra hypofractionated radiotherapy volumetric intensity modulated arc radiation therapy to a dose of 35Gy in 5 fractions. High-risk group patients also received elective pelvic nodal radiation to a dose of 25 Gy in 5 fractions simultaneously. Intermediate and high-risk patients also received androgen deprivation therapy for six months and two years, respectively. The toxicities were recorded using CTCAE v4.0, and patient-reported outcomes were measured using the International Prostate Symptom Score (IPSS) and the EORTC quality of life questionnaire (EORTC-QLQ) C30 and PR25 questionnaires and PR25 questionnaires. The follow-up data of these patients were analysed to calculate the long term oncological outcomes, late toxicities and long-term patient-reported outcomes.

Results:

The majority of patients had Gleason 7 (50%) and T3 (60%) disease. The median PSA was 17 ng/ml. High-risk disease was present in 20 patients (66.7%). With a median follow-up of 90 months, the 7-year biochemical failure-free survival is 80% in the high-risk group and 78% in the low-intermediate risk group patients. The 7-year distant metastasis-free survival is 80% in the high-risk group and 100% in low-intermediate risk. The overall survival at seven years is 68% in the high risk and 80% in the low-intermediate risk. The incidence of grade 2 or more late proctitis is 6.7% (n=2), and grade 2 or more late cystitis is 16.6% (n=5). No patient had grade 2 or more late small bowel toxicity. In patient-reported outcomes, the average change from baseline in the scaled score (on 100) at the end of RT, 4-7 months, 10-14 months, 20-26 months and >26 months was +14, +6, +7, +5 and +6 for a composite of urinary symptoms on the PR25 scale. The only clinically meaningful change (>+10) was seen at end-of-RT. The corresponding values on a composite of bowel symptoms were +2, +4, +4, +4, and +7, suggesting clinically insignificant changes overall. The change in the total IPSS symptom score from baseline (on a scale of 35) at the same time periods were +7, +1, +2, -1, and 0, suggesting a return close to baseline within six months of RT completion.

Conclusion:

Long-term outcomes of ultra hypofractionated radiation therapy with modest doses and once weekly fractionation with androgen deprivation therapy to high-risk diseases are very encouraging. Toxicities were modest, and patient reported outcomes suggest only short-term worsening of symptoms.

Keywords: Ultrafractionation, Prostate cancer, PRO

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