Benefit of prophylactic pelvic irradiation in intermediate-risk prostate cancer: A multicenter retrospective study (iPPAPI)

Abstract

Context.

Prostate cancer (PCa) is the most common urologic malignancy in men, with most cases diagnosed at a localized stage. The benefit of whole-pelvic radiotherapy (WPRT) to eradicate subclinical nodal disease remains debated, particularly in intermediate-risk PCa. This study assessed the impact of WPRT in this population.

Methods

We conducted a multicenter retrospective study within the AP-HP GRRAP program across five radiotherapy departments. Biopsy-proven intermediate-risk PCa (d’Amico classification) treated with conformational external beam radiotherapy between 2010 and 2019 were included. The primary endpoint was recurrence-free survival (RFS), defined as time from diagnosis to biochemical, local, metastatic recurrence, or death. Secondary endpoints were overall survival (OS) and acute (<6 months) or late (≥6 months) genitourinary (GU), gastrointestinal (GI), and sexual toxicities (CTCAE v4.03/v5.0). Survival outcomes were assessed using univariate and multivariate Cox models.

Results

Three hundred patients (60 per center) were included; 94 % received IMRT and 6 % 3D-RT. After a median follow-up of 77 months, univariate analysis showed no significant association between WPRT and RFS (HR; 0.61; 95 % CI, 0.26–1.42; p = 0.25). Multivariable analysis adjusted for clinical and treatment factors yielded similar results (HR, 0.70; 95 % CI, 0.27 to 1.81; p = 0.46). OS results were also comparable. Rates of grade 2 acute or late toxicities were similar, but grade ≥ 3 late GI toxicity was higher with WPRT (14.3 % vs. 5.4 %; p = 0.045; OR 2.90).

Conclusion

In intermediate-risk PCa, WPRT did not improve RFS or OS compared with prostate-only RT but was associated with an increased risk of severe GI toxicity.