THE RISK OF A DIAGNOSIS OF CANCER AFTER PRIMARY DEEP VENOUS THROMBOSIS OR PULMONARY-EMBOLISM

Background Several small studies have indicated an association between deep venous thrombosis or pulmonary embolism and a subsequent diagnos is of cancer, but the subject is controversial. Methods We conducted a nationwide study of a cohort of patients with deep venous thrombosis or pulmonary embolism that was drawn from the Danish National Registry of Patients for the years 1977 th rough 1992. The occurrence of cance r in the cohort was determined by linkage to the Danish Cancer Registr y. The expected number of cancer cases was estimated on the basis of n ational age-, sex-, and site-specific incidence rates. Results A total of 15,348 patients with deep venous thrombosis and 11,305 patients wi th pulmonary embolism were identified. We observed 1737 cases of cance r in the cohort with deep venous thrombosis, as compared with 1372 exp ected cases (standardized incidence ratio, 1.3; 95 percent confidence interval, 1.21 to 1.33). Among the patients with pulmonary embolism, t he standardized incidence ratio was 1.3, with a 95 percent confidence interval of 1.22 to 1.41. The risk was substantially elevated only dur ing the first six months of follow-up and declined rapidly thereafter to a constant level slightly above 1.0 one year after the thrombotic e vent. Forty percent of the patients given a diagnosis of cancer within one year after hospitalization for thromboembolism had distant metast ases at the time of the diagnosis of cancer. There were strong associa tions with several cancers, most pronounced for those of the pancreas, ovary, liver (primary hepatic cancer), and brain. Conclusions An aggr essive search for a hidden cancer in a patient with a primary deep ven ous thrombosis or pulmonary embolism is not warranted. (C)1998, Massac husetts Medical Society.