Radiation therapy for oligorecurrence in prostate cancer. Preliminary results of our centre

There is growing interest in the use of more aggressive therapeutic modalities for treating metastatic prostate cancer. In this study, we examine the use of stereotactic body radiation therapy (SBRT) for patients with oligorecurrent prostate cancer. We analysed the biochemical response and toxicity of patients who underwent this therapy at our centre.

We selected patients who experienced oligorecurrence between January 2015 to December 2016 and were administered SBRT. The association of androgen deprivation (AD) was left in each case to the decision of the tumour committee. We describe the clinical situation at diagnosis of oligorecurrence, the treatment administered and the biochemical response. We considered a biochemical response to be a 50% reduction in the absolute prostate-specific antigen (PSA) readings.

SBRT was administered to 11 patients with bone (82%) and/or lymph node oligometastasis (18%). The treatment regimen for bone oligometastasis was 27Gy divided into 3 sessions, while the treatment for lymph node oligometastasis reached 70Gy. Seven patients had no treatment at the time of diagnosis, 2 were in the castration-resistant phase, 1 patient was in the off phase of intermittent AD, and 1 patient had adjuvant AD for pN1. Seven patients presented a biochemical response with a PSA reduction of 75-100%. The response was not assessable in 4 patients due to the continuing adjuvant AD. With a mean follow-up of 10.5 months, only 2 patients had progressed. Grade 1 gastrointestinal toxicity was detected in only 1 patient.

Our data suggest that the use of SBRT in carefully selected patients with metastatic oligorecurrence of prostate cancer can achieve biochemical response and potentially delay progression and the use of systemic treatments.