MON-416 - The Risk of Venous Thromboembolism in Thyroid Cancer: A National Inpatient Sample 2015-2020 Database Study

Background:
Cancer is a well-established prothrombotic state and a risk factor for venous thromboembolism (VTE), including deep venous thrombosis and pulmonary embolism. However, data on VTE risk in thyroid cancer are limited and inconclusive, possibly because of its favorable oncologic prognosis. In 2025, thyroid cancer accounted for approximately 44,000 cases (2.2% of all cancers) and 2,290 deaths (0.4% of cancer deaths), with a 98.4% 5-year relative survival (1). The objective of this study was to evaluate the incidence of VTE in thyroid cancer and compare it with cancer-free admissions and other common malignancies.

Methods:
This study used the National Inpatient Sample (NIS) database to extract inpatient admission data using ICD-10 codes and analyzed data from Q4 2015 to 2020. Exclusion criteria included age < 18 years, missing age, pregnancy, antiphospholipid syndrome, and primary thrombophilias (including activated protein C resistance, prothrombin gene mutation, antithrombin III deficiency, and protein C or S deficiency). Weights were applied to the NIS dataset as advised by HCUP (Healthcare Cost and Utilization Project). Statistical analyses were performed using SAS version 9.4 (SAS Institute Inc., 2023).

Results:
After applying the exclusion criteria, the study examined 134,866,701 admissions. We examined the incidence of VTE for 16 common cancers: prostate, thyroid, colon, breast, melanoma, Hodgkin’s lymphoma, non-Hodgkin’s lymphoma, lymphoid leukemia, bladder, kidney, gallbladder, stomach/small intestine, ovarian, lung, uterine, and pancreatic. Among cancer-free admissions (admissions without any of the above cancers), VTE incidence was 2.85%. Among cancer-associated admissions, VTE incidence varied by malignancy and was observed in prostate (4.04%), thyroid (4.11%), colon (5.58%), breast (5.87%), melanoma (6.07%), lung (8.83%), and uterine cancer (9.85%). Admissions with thyroid cancer had a higher VTE incidence than cancer-free admissions and were comparable to several traditionally higher-risk malignancies. Notably, the incidence of VTE in thyroid cancer admissions increased over time, from 3.96% in 2015 to 4.95% in 2020.


Conclusions:
Despite a generally indolent clinical course, thyroid cancer is associated with a higher incidence of VTE than in cancer-free admissions and shows a rising VTE burden over time. These findings suggest that thyroid cancer-associated VTE may be under-recognized and warrant further investigation. Future studies should evaluate VTE risk across cancer subtypes, explore underlying mechanisms, and assess whether thyroid cancer status should inform VTE risk stratification and screening.

Citation: (1) Cancer Stat Facts: Thyroid Cancer. NIH National Cancer Institute Surveillance, Epidemiology, and End Results Program. Retrieved January 21 from seer.cancer.gov/statfacts/html/thyro.html

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