Unique Characteristics and Outcomes of Patients Diagnosed With Both Primary Thyroid and Primary Renal Cell Carcinoma

Abstract

Patients with multiple primary malignancies may exhibit unique clinical characteristics that suggest a common predisposition or lead to different disease management. Given the association of primary thyroid (TC) and renal cell carcinoma (RCC), we characterized the clinicopathologic features of patients treated for both malignancies (TC/RCC). TC/RCC patients were identified through the institutional tumor registry and using data compiled by retrospective chart review. To compare with broader institutional and national cohorts, we examined patients admitted with TC or RCC institution-wide and reviewed the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) program for these cancers. Overall, 51% of patients developed TC before RCC, 27% developed RCC before TC, and 22% were diagnosed within 1 year of each other. The mean age at TC diagnosis was 52 ± 15 (18-77), which was significantly older than institutional TC patients (45 ± 16.5 years, P≤.0001), and the mean age at RCC diagnosis was 59 ± 12 (32-79). The TC/RCC cohort had a balanced sex distribution (51% female) compared with the institutional TC group (67% female, P = .0003) and the institutional RCC group (31% female, P<.0001). Similar age and sex ratio differences were seen when compared with SEER cohorts. In the TC/RCC cohort, 43% of patients developed other cancers (52% of females, 33% of males; P = .04); among the females, 45% developed breast cancer. Individuals who develop both TC and RCC may represent a unique subset of cancer patients. Further prospective research is warranted to explore the unanticipated association with breast cancer in female patients and to investigate a possible common pathogenesis underlying these malignancies.