Background: Whole pelvic irradiation in prostate cancer patients might prevent metastatic spread of cancer cells through lymphatic drainages in patients eligible for definitive radiotherapy, but its use has declined in the last decades in favor of prostate-only irradiation (POI). The aim of our study is to assess the incidence of pelvic lymph nodal relapse and outcome in prostate cancer patients receiving POI.
Materials and methods: Data from 207 consecutive patients were collected. Clinical and treatment variables were collected. Biochemical relapse-free survival (BRFS), pelvic nodal relapse-free survival (PNRFS), distant metastasis-free survival (DMFS), disease-specific survival (DSS) and overall survival (OS) were calculated; analysis of prognostic variables was performed.
Results: Five-year BRFS, PNRFS, DMFS, DSS and OS were, respectively, 90, 98, 96, 97 and 91%. On multivariate analysis, independent negative predictors of BRFS were Gleason score ≥ 7 (HR: 3.25) and PSA nadir ≥ 0.08 (HR: 4.86). Pelvic nodal relapse was not correlated to impaired outcome.
Conclusions: Lymph nodal pelvic relapse occurs in 2% of patients at 5 years and does not correlate with impaired outcome, suggesting the lack of theoretical benefit of a prophylactic nodal irradiation. Tumor biology and response to treatment are the main determinants of outcome.

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Keywords Definitive radiotherapy, Prostate cancer, Prostate-only irradiation, Whole pelvic irradiation
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Journal La Radiologia Medica
Loi, M, Incrocci, L, Desideri, I. (Isacco), Bonomo, P. (Pierluigi), Detti, B. (Beatrice), Simontacchi, G. (Gabriele), … Livi, L. (Lorenzo). (2018). Prognostic impact of nodal relapse in definitive prostate-only irradiation. La Radiologia Medica, 1–7. doi:10.1007/s11547-018-0888-1