IMRT Yields Similar QOL Vs Proton Therapy in Localized Prostate Cancer

Investigators of the multi-center, randomized phase 3 PARTIQoL trial (NCT01617161) assessed patient-reported QOL among those who received IMRT or proton beams to determine which modality conferred the best reductions in adverse effects.

Intensity-modulated radiation therapy (IMRT) and proton beam therapy yielded comparable quality of life (QOL) outcomes and effective tumor control among patients with localized prostate cancer, according to findings from the phase 3 Prostate Advanced Radiation Technologies Investigating Quality of Life (PARTIQoL) trial (NCT01617161) presented in a press briefing at the 2024 American Society for Radiation Oncology Annual Meeting (ASTRO).¹

Regarding bowel function at 24 months per Expanded Prostate Cancer Index (EPIC) assessments, the mean changes in bowel scores were –2.2 from baseline in the IMRT arm compared with –2.4 in the proton therapy arm (P = .84). At 24 months, the mean changes in urinary incontinence scores were –3.4 and –3.5 in each respective arm (P = .99).

The mean changes in urinary irritation scores were 0.8 following IMRT and 1.0 with proton therapy at 24 months (P = .85). After 24 months of treatment, the mean changes in sexual QOL scores were –6.0 and –10.6 with IMRT and proton therapy, respectively (P = .05).

The progression-free survival (PFS) rates were 99.0% in the IMRT arm vs 98.1% in the proton therapy arm at 24 months. Additionally, the 60-month PFS rates were 93.7% vs 93.4% in each arm (HR, 1.16; P = .71).

When assessing bowel QOL outcomes across treatment arms, investigators reported no differences based on whether patients were 65 years or younger or older than 65 years; similar outcomes occurred regardless of whether patients had intermediate- or low-risk disease. Additionally, there were no differences in bowel outcomes regardless of the use of rectal spacer or whether patients underwent conventional or hypofractionated radiotherapy schedules.

“IMRT and proton therapy offer patients with localized prostate cancer equally excellent [QOL] outcomes with highly effective tumor control, without measurable differences between the 2 approaches,” Jason A. Efstathiou, MD, PhD, FASTRO, a professor of radiation oncology at Harvard Medical School; vice-chair of Faculty & Academic Affairs and director of the Genitourinary (GU) Division in the Department of Radiation Oncology and clinical co-director of The Claire and John Bertucci Center for GU Cancers at Massachusetts General Hospital, said in a presentation on these data.¹ “We continue to monitor [patients] for longer follow-up and secondary end points, as well as the results from our companion registry.”

Investigators of the multi-center, randomized phase 3 PARTIQoL trial assessed patient-reported QOL among those who received IMRT or proton beams to determine which modality conferred the best reductions in adverse effects (AEs). A total of 450 patients with localized prostate cancer were randomly assigned to receive proton beam therapy or IMRT, with investigators assessing end points at baseline and 3, 6, 9, 12, 18, 24, 36, 48, and 60 months after initiating treatment.

The trial’s primary end point was bowel function at 24 months based on EPIC assessments. Secondary end points included urinary and erectile function, health-related QOL and utilities, perceptions of care, AEs, efficacy end points, economic end points, and response biomarkers.

Patients 18 years and older with histologically confirmed adenocarcinoma of the prostate based on core biopsy within a year of study entry and clinical stage T1c to T2c disease were eligible for enrollment on the trial.² Other requirements for enrollment included having a prostate-specific antigen level of less than 20 within 6 months of study entry and an ECOG performance status of 0 or 1.

Investigators stratified patients based on clinical trial site, age, rectal spacer use, and receipt of moderate hypofractionation. Patients received radiotherapy at a planned fractionation schedule of 1.8 Gy fractions to 79.2 Gy or 2.5 Gy to 70.0 Gy.

Of 450 randomly assigned patients, 226 were assigned to the proton beam therapy arm. Of these patients, 221 initiated study treatment, 202 completed EPIC bowel assessments at baseline, and 167 finished bowel assessments at 24 months. Additionally, of 224 patients who were assigned to the IMRT arm, 216 began treatment, 195 completed bowel assessments at baseline, and 162 finished bowel assessments at 24 months.

References

1. Efstathiou JA, Yeap BY, Michalski JM, et al. Prostate advanced radiation technologies investigating quality of life (PARTIQoL): phase III randomized clinical trial of proton therapy vs. IMRT for localized prostate cancer. Presented at the 2024 American Society for Radiation Oncology Annual Meeting (ASTRO); September 29 – October 2, 2024; Washington, DC. Abstract LBA01.
2. Proton therapy vs. IMRT for low or intermediate risk prostate cancer (PARTIQoL). ClinicalTrials.gov. Updated October 26, 2023. Accessed September 30, 2024. https://tinyurl.com/3h7n2t68