Presentation Authors: Sohrab Arora*, Akshay Sood, Deepansh Dalela, Jacob Keeley, Alex Borchert, Lee Baumgarten, Craig G Rogers, James Peabody, Mani Menon, Firas Abdollah, Detroit, MI
Introduction: American Joint Committee on Cancer (AJCC) recognizes five rare histological variants of PCa. Our aim was to describe the contemporary presentation and overall survival (OS) of these rare variants.
Methods: We focused on 1345561 PCa patients diagnosed between 2004-2015 within the NCDB. The cases included nonvariant PCa, and 5 rare variants of adenocarcinoma, namely, ductal, neuroendocrine (NEC), mucinous, signet ring cell (SRC), and adenosquamous PCa. Characteristics at presentation for each variant were compared with nonvariant PCa. Regression analyses tested the effect of histological subtype on OS.
Results: Overall, 5062 (0.38%) patients presented with rare-variant PCa. All rare variants presented with an advanced local stage (Stage â‰¥ cT3 43.4%, 42.2%, 18.9%, 16%, and 9.2%, in NEC, adenosquamous, ductal, SRC, and mucinous variants, respectively), compared to 5.9% in 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 â‰¥ 4 (34.7%, 11.2%, and 27%, respectively vs. 8.6% in nonvariant PCa; all p < 0.001). At a median follow up of 5.3 years, estimated OS was highest in mucinous variant (88.7%), followed by nonvariant (86.3%), ductal (75.2%), SRC (66.2%), adenosquamous (20.5%), and NEC PCa (13.1%). After adjusting for covariates, regression analyses confirmed variant histology to be an independent predictor of OS.
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.