Presenter(s)
C. A. Jones1, J. Haseltine2, V. S. Brennan2, Z. R. Moore2, D. J. Gorovets2, S. M. McBride2, M. A. Kollmeier3, T. P. Kole2, H. Nagar2, and J. Janopaul-Naylor2; 1Brody School of Medicine at Eastern Carolina University, Greenville, NC, 2Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY, 3DepMemorial Sloan Kettering Cancer Center, New York, NY
Purpose/Objective(s): While the vast majority of prostate cancer presents as prostatic adenocarcinoma, it can present as or transform into neuroendocrine carcinoma (NEPC). Due to its rarity, we have limited data on effective radiation approaches. This study reports efficacy of radiation treatments on neuroendocrine prostate cancer in and outside the prostate.
Materials/Methods: We reviewed 29 patients with 86 total radiation courses of radiotherapy for neuroendocrine prostate cancer of which 73 sites had follow-up imaging. Covariates included de novo (n=8) vs transformed (n=11) vs partially differentiated (n=10) neuroendocrine carcinoma, body site radiated, radiation dose and fractionation, and imaging follow-up for each site treated. Endpoints assessed include overall survival and local control based on clinical and radiographic findings. The Kaplan Meier method and log-rank test in R were used.
Results: The median radiographic follow-up for the 73 lesions with post-treatment imaging was 349 days (IQR 128 – 1,034 days). Median survival for men with de novo, transformed, and partially differentiated NEPC was 37 months, 4 months, and not reached respectively. No patient with transformed NEPC survived >12 months. In total, 25 men had their prostate treated with median BED10 of 45 Gy (range 25-102 Gy) with no local failures. Other sites treated included bones (n=40), lymph nodes (n=3), brain (n=3), and lung (n=2). There was only 1 local failure. The local failure occurred in a 71-year-old man with focal neuroendocrine differentiation 2 years after an initial dose of 3000 cGy in 5 fractions to an iliac lymph node. There were no local failures in patients with pure de novo or transformed NEPC. There were 9 courses of a single 800 cGY, none of which experienced a local failure, but limited to 199 days of follow-up in this subset.
Conclusion: NEPC in the prostate and bones appears to be highly radiosensitive in this sample. Patients with transformed NEPC had poor prognosis but no local radiation failures in limited follow-up. Given one relapse after SBRT, select patients with good prognosis may benefit from ablative treatment; however, further work is needed to clarify the largely palliative role of radiotherapy for men with NEPC.