(UroToday.com) The 2024 ASTRO annual meeting included a session on the management of small-cell neuroendocrine tumors of the genitourinary tract, featuring a presentation by Dr. Emily Weg discussing the role of radiation therapy for small-cell neuroendocrine tumors of the genitourinary tract. Dr. Weg notes that primary small cell carcinoma of the prostate has an incidence of <1%, with >25% of patients presenting with a PSA < 4 ng/mL.
Approximately 40% of patients present with lower urinary tract symptoms, 20% with bladder outlet obstruction, and 18% with bone pain. Moreover, approximately 40% present with T3-T4 disease, 50% present with N1 disease, and 60-70% present with de novo metastatic disease to the bone and viscera. The median overall survival for locoregional disease is 15 months, whereas for metastatic disease is 7 months.
Dr. Weg then discussed two cases, starting with a case of a 57-year-old male who presented with urinary obstruction and was diagnosed with 14/14 cores of mixed Gleason 5+4 adenocarcinoma with a small cell component. His PSA was 2.36 ng/mL and staging (CT, bone scan, and FDG PET) showed prostatomegaly with associated bladder neck invasion and a 1.8 cm left external iliac lymph node; an MRI of the brain was negative. He then underwent concurrent carboplatin + etoposide for five cycles, ADT for 18 months with IMRT to 50.4/56/75.6 Gy, completed in 2014. To date, he has received a CT chest/abdomen/pelvic every 6 months for 5 years, in addition to regularly scheduled PSA surveillance.
Based on a SEER analysis from Wang and colleagues in 2019,1 among 260 patients with prostate small cell carcinoma (2004-2015), chemotherapy was associated with improved overall survival for node-positive and metastatic small cell carcinoma of the prostate patients. Specifically, chemotherapy improved the median overall survival from 3 to 12 months among node-positive patients, and from 2 to 9 months for metastatic patients:
The second case was a 65-year-old male who presented with de novo M1 prostate adenocarcinoma in January 2023 involving the nodes, bones, and lung. He was subsequently treated with triplet therapy and in January 2024 presented with a symptomatic, bulky prostate mass, with biopsy showing small cell transformation. In March 2024, he received carboplatin + etoposide for four cycles, with symptomatic response but progression between cycles. He was then referred for consideration of palliative radiotherapy, undergoing radiotherapy to the prostate mass to 30 Gy in 5 fractions, completed in May 2024 with symptomatic improvement:
Dr. Weg concluded her presentation discussing the role of radiation therapy for small cell neuroendocrine tumors of the genitourinary tract with the following take-home points:
- Small cell carcinoma of the prostate tends to present symptomatically, often with locally advanced disease and regional/distant metastasis
- The initial workup can include FDG PET and MR brain
- Post-treatment follow-up should include regular PSA surveillance along with surveillance imaging
- Radiotherapy can be offered with definitive intent for locoregional disease, with systemic therapy as the priority
- Radiotherapy can offer local control and symptomatic relief for locally advanced disease
- There are many unanswered questions, including:
- What is the optimal dose and fractionation when treating small cell carcinoma of the prostate patients?
- Is there a role for radiotherapy to the prostate in metastatic small cell carcinoma of the prostate?
Presented by: Emily Weg, MD, Radiation Oncologist, University of Washington, Seattle, WA
Written by: Zachary Klaassen, MD, MSc – Urologic Oncologist, Associate Professor of Urology, Georgia Cancer Center, Wellstar MCG Health, @zklaassen_md on Twitter during the 2024 American Society for Radiation Oncology (ASTRO) Annual Meeting, Washington, DC, Sun, Sept 29 – Wed, Oct 2, 2024.
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