PET-Guided Radiotherapy Shows Lasting Control of Recurrent Prostate Cancer

A new retrospective study with a 10-year follow-up suggests that some men with prostate cancer recurring only in lymph nodes may achieve prolonged disease control using PET-directed radiotherapy combined with temporary androgen deprivation therapy (ADT).

The retrospective study included 93 men with hormone-sensitive prostate cancer that had returned in pelvic and/or para-aortic lymph nodes after previous treatment intended to cure the disease. PET imaging identified a median of two positive lymph nodes, while patients had a median PSA of 2.7 ng/mL at recurrence.

Rather than irradiating only the visible metastases, patients received elective nodal radiotherapy covering the relevant lymphatic region, with a higher simultaneous radiation dose delivered to the PET-positive nodes. Most also received temporary ADT for a median of approximately two years.

After a median follow-up of 10 years, overall survival was 95% at five years and 77% at ten years, while prostate cancer-specific survival was 96% and 87%, respectively. Importantly, 55% of patients remained free from castration-resistant prostate cancer at ten years.

Long-term disease control was more difficult to maintain: biochemical relapse-free survival was 46% at five years and 38% at ten years, while distant metastasis-free survival was 54% and 31%. Nevertheless, 35% of patients remained free from additional treatment ten years after the original salvage strategy.

The location of recurrence also appeared important. Men whose disease was confined to pelvic lymph nodes had a 10-year overall survival of 93%, compared with 70% among those with common iliac or para-aortic involvement. Prostate cancer-specific survival was 96% versus 83%.

Despite treating relatively large nodal regions, serious late toxicity remained uncommon. At ten years, grade 3 genitourinary toxicity was 4.3% and grade 3 gastrointestinal toxicity 1.1%.

The study does not prove that this approach is superior to other strategies: it was retrospective, included selected patients and reflects treatments delivered in an earlier therapeutic era. Modern PSMA PET, metastasis-directed radiotherapy and systemic intensification have also changed the landscape considerably.

However, ten years of follow-up provides something rarely available in oligorecurrent prostate cancer studies. The results suggest that PET-detected nodal recurrence does not necessarily require indefinite systemic treatment from the outset and that, in selected hormone-sensitive patients, aggressive treatment of the nodal disease combined with a finite period of ADT may produce remarkably prolonged periods without castration resistance or further therapy.

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