Abstract 4209: Cancers of unknown primary: survival by histologic type, demographic features, and treatment in the US Military Health System

Abstract

Abstract Background: Cancers of unknown primary (CUP), a group of heterogenous metastatic cancers lacking a known primary site, have poor prognosis. This study compared survival by histologic type, patient characteristics, and treatment in the U.S. Military Health System (MHS), which provides universal care to its members. Methods: Patients diagnosed with CUP were identified from the U.S. Department of Defense’s Automated Central Tumor Registry. Median survival with 95% confidence intervals was calculated for demographic and treatment variables by histologic type. A multivariable accelerated failure time model estimated time ratios and 95% confidence intervals. Results: The study included 3,358 CUP patients. The most prevalent CUP in this study was well and moderately differentiated adenocarcinomas. Median survival varied by histologic type with squamous cell carcinoma having the longest at 25.1 months and poorly differentiated carcinomas having the shortest at 3.0 months. For each histologic type, survival was generally similar by sex and active-duty status. Younger patients tended to have longer survival than those aged 65 years or older. Women with well and moderately differentiated adenocarcinoma had longer survival than their male counterparts. Generally, there were no racial differences in survival except poorer survival for Blacks than Whites with other histologic types. Patents with chemotherapy and radiation treatment generally had improved survival whereas patients with squamous cell carcinoma who received chemotherapy had shorter survival than those without. Conclusion: Survival generally did not differ between racial groups, which may be related to equal healthcare access despite racial background. Further studies are warranted to better understand how survival in the MHS compares with that in the general U.S. population. Disclaimer: The contents of this publication are the sole responsibility of the authors and do not necessarily reflect the views, opinions or policies of USUHS, HJF, the DoD or the Departments of the Army, Navy or Air Force. Mention of trade names, commercial products or organizations does not imply endorsement by the US Government. Citation Format: Julie A. Bytnar, Jie Lin, Joel T. Moncur, Craig D. Shriver, Kangmin Zhu. Cancers of unknown primary: survival by histologic type, demographic features, and treatment in the US Military Health System. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4209.