Anatomic Patterns of Recurrence Following Biochemical Relapse in the Dose-Escalation Era for Prostate Patients Undergoing External Beam Radiotherapy.

To provide a comprehensive analysis of anatomic patterns of recurrence following external beam radiotherapy (EBRT) for localized prostate cancer (PC) patients.

This retrospective analysis included 2694 patients with localized PC receiving definitive dose-escalated EBRT from 1991 to 2008. First-recurrence sites (FRS) were defined as initial sites of clinically detected recurrence (CDR) and any subsequent CDR within 3 months. Anatomic recurrence patterns were classified as local (prostate/seminal vesicles only), lymphotropic (lymph nodes [LN] only), and osteotropic (bones only) for patients with disease confined solely to these respective sites for at least 2 years from initial CDR.

Prostate was the most common FRS for all risk groups (8-year cumulative incidence, 3.5%, 9.8%, and 14.6% for low-, intermediate-, and high-risk patients, respectively). Eight-year risk of isolated pelvic LN relapse as FRS was 0%, 1.0%, and 3.3%, respectively. For the 474 patients experiencing CDR, the most common FRSs were local (55.3%), bones (33.5%), pelvic LN (21.3%), and abdominal LN (9.1%). Patients displayed unique relapse distributions, including local (41.6%), lymphotropic (9.7%), osteotropic (20.3%), and multiorgan/visceral (28.5%) patterns. Anatomic recurrence pattern was the strongest predictor for PCSM in a multivariate analysis of CDR patients.

The most common FRS after dose-escalated EBRT for PC is within the prostate and SV for all risk groups. By contrast, patients treated without elective pelvic LN irradiation have a relatively low risk of isolated pelvic LN relapse. Recurrence patterns displayed a tropism for specific anatomic distributions, with divergent prognoses, suggesting underlying biological differences amongst tumors.

J Urol. 2015 Jul 9. pii: S0022-5347(15)04327-X. doi: 10.1016/j.juro.2015.06.100. [Epub ahead of print]

Zumsteg ZS1, Spratt DE1, Romesser PB1, Pei X1, Zhang Z1, Kollmeier M1, McBride S1, Yamada Y1, Zelefsky MJ2.

1 Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY.
2 Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY.