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SEER Inquiry System - Report
Produced: 05/15/2026 2:21 PM
Question 20190083
Inquiry Details
References:
Solid Tumor Rules. Other Sites, Updated 9/11/2018
Question:
Solid Tumor Rules (2018)/Multiple primaries--Prostate: How many primaries should be reported when metastatic small cell carcinoma of the prostate is diagnosed at the same time as adenocarcinoma of the prostate? See Discussion.
Discussion:
Patient has biopsy of prostate 12/28/2018 showing Gleason 5+5 adenocarcinoma. Liver biopsy on same date is metastatic small cell carcinoma consistent with prostate primary. Oncology consult states that liver biopsy is likely neuroendocrine conversion from prostate carcinoma. Patient also has bone metastasis and receives radiation, Lupron, Casodex, and chemotherapy of carboplatin and etopiside.
Per Solid Tumor Rules, we code histology from primary site over a metastatic site. Thus, the small cell carcinoma, which appears to be the focus of the chemotherapy is lost. Is it correct to code this as a single primary with an adenocarcinoma histology?
Both SINQ 20130221 and 20180088 instruct us to abstract multiple primaries when patient develops a metastatic small cell carcinoma of the prostate after being previously diagnosed with adenocarcinoma of the prostate.
Answer:
Accession two primaries, adenocarcinoma [8140/3] of the prostate [C619] and small cell neuroendocrine carcinoma [8041/3] of the prostate [C619] per Rule M17 of the Other Sites Solid Tumor Rules 2018, as these are different histologies with different histology codes at the second number.
Adenocarcinoma of prostate often manifests as a small cell carcinoma following treatment or as a progression of disease. It is important to capture these tumors as new primaries.
