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Henry Ford Hospital


Introduction and Objective: American Joint Committee on Cancer (AJCC) recognizes five rare histological variants of prostate adenocarcinoma (PCa). Our aim was to describe the contemporary presentation and overall survival (OS) of these rare variants. Methods: From 2004-2015, we selected cases of mucinous, ductal, signet ring cell (SRC), Adenosquamous, and neuroendocrine (NEC) variants of PCa from the National Cancer Database. Characteristics at presentation for each variant were compared with nonvariant PCa. Cox regression was used to study the effect of histological subtype on overall mortality. Results: Less than 1 percent (5062/1345561; 0.38%) patients presented with rare-variant PCa. All variants had a higher clinical T stage at presentation than nonvariant PCa (all p<0.001; Table 1). Metastatic disease was most common with NEC (62.9%), followed by adenosquamous (31.1%), SRC (10.3%), and ductal (9.8%) variants, compared to 4.2% in nonvariant PCa (all p<0.001). Metastatic disease in mucinous (3.3%) was similar to nonvariant PCa (p = 0.15). SRC, mucinous, and ductal variants presented with a significantly higher PSA (Median 9.0, 6.7, and 6.6, respectively vs. 6.2 ng/ml in nonvariant PCa; all p < 0.001), and higher biopsy grade (Grade group ≥ 4 (34.7%, 11.2%, and 27%, respectively vs. 8.6% in nonvariant PCa; all p < 0.001). Estimated 5-year OS was highest in mucinous variant (89.3%), followed by nonvariant (87.2%), ductal (76.4%), SRC (67.0%), adenosquamous (20.5%), and NEC PCa (13.4%). After adjusting for covariates—compared to nonvariant PCa—mortality was significantly higher in ductal, SRC, adenosquamous, and NEC variants (Table 2) Conclusions: There are differences in the presentation and OS among rare variants of PCa. NEC, adenosquamous, signet ring cell, and ductal variants more commonly present with metastatic disease. All variants present with a higher local stage than nonvariant PCa. NEC variant is associated with the worst, and mucinous variant with the best OS.

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Rare Histological Variants of Prostate Adenocarcinoma (PCa):  NCDB Analysis