The concept of metastasis-directed therapy for nodal oligorecurrences with stereotactic body radiotherapy is increasingly accepted. Hence, the comparison between salvage extended field radiotherapy (s-EFRT) and salvage involved field radiotherapy (s-IFRT) in patients with 18F-fluorocholine (FCH) PET/CT+ nodal oligorecurrences from prostate cancer is worthy of investigation.

Patients with oligorecurrent nodes on FCH PET/CT treated with salvage radiotherapy between 2009 and 2017 in a single tertiary cancer centre were selected for this study. Patients treated with s-IFRT were compared with those treated with s-EFRT. Toxicities and times to failure (TTF) were compared between the two groups.

The study included 62 patients with positive lymph nodes only who underwent FCH PET/CT for a rising PSA level after radical prostatectomy or radiotherapy. Of these patients, 35 had s-IFRT and 27 had s-EFRT. After a median follow-up of 41.8 months (range 5.9-108.1 months), no differences were observed in acute or late gastrointestinal and genitourinary toxicities of grade 2 or more between the two groups. The 3-year failure rates were 55.3% (95% CI 37.0-70.3%) in the s-IFRT group and 88.3% (95% CI 66.9-96.1%) in the s-EFRT group (p = 0.0094). In multivariate analysis of TTF, an interval of >5 years was significantly correlated with better outcomes (HR = 0.33, 95% CI 0.13-0.86, p = 0.023). There was a strong trend toward better outcomes with s-EFRT even after adjusting for concomitant androgen-deprivation therapy (HR = 0.38, 95% CI 0.12-1.27, p = 0.116).

FCH PET-positive node-targeted s-EFRT is feasible with low rates of toxicity and longer TTF, suggesting that oligorecurrent nodal disease diagnosed on FCH PET is unlikely.

European journal of nuclear medicine and molecular imaging. 2018 Sep 28 [Epub]

Alexis Lépinoy, Yannick E Silva, Etienne Martin, Aurélie Bertaut, Magali Quivrin, Léone Aubignac, Alexandre Cochet, Gilles Créhange

Department of Radiation Oncology, University Hospital Jean Minjoz, 25000, Besançon, France., Department of Nuclear Medicine, Unicancer-Georges François Leclerc Cancer Center, 21000, Dijon, France., Department of Radiation Oncology, Unicancer-Georges François Leclerc Cancer Center, 21000, Dijon, France., Department of Biostatistics, Unicancer-Georges François Leclerc Cancer Center, 21000, Dijon, France., Department of Medical Physics and Radiation Oncology, Unicancer-Georges François Leclerc Cancer Center, 21000, Dijon, France., Department of Radiation Oncology, Unicancer-Georges François Leclerc Cancer Center, 21000, Dijon, France. .

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