[Intermediate-risk prostate cancer treated with exclusive external irradiation: Focus on anatomical sites of recurrence in two French trials].

Purpose: Retrospective description of anatomical sites of relapse based on (18F)-choline PET-CT, (68Ga)-prostatic specific-membrane antigen PET-CT, bone scan, and prostate magnetic resonance imaging (MRI) data.

Materials And Methods: From two French prospective cohorts, patients treated with exclusive radiotherapy for an intermediate-risk cancer were identified during their follow-ups. They were included if they presented a rising of the prostate-specific antigen (PSA) associated with the realization of an imaging showing the sites of recurrences.

Results: Two hundred and sixty-three patients were included. After a median follow-up of 76 months (interquartile range [IQR] 67-95), 65 patients had biochemical recurrence and positive imaging. The median nadir PSA was 0.6ng/mL and the median PSA at recurrence was 3.4ng/mL. A single lesion was found in 48% of cases, 2 to 4 lesions in 43% of cases and more than 4 lesions in 9% of cases. The sites of relapse identified were prostate (37/65), prostate only (19/65), seminal vesicles (9/65) Pelvic nodes (35/65), extrapelvic nodes (15/65) and bone (13/65).

Conclusions: The majority of relapses presented as a single lesion localized in the pelvis.