Idiopathic superficial thrombophlebitis and the incidence of cancer in primary care patients.

PURPOSE The association of spontaneous venous thromboembolism with occult malignancy is well established. Less clear is the incidence of subsequent cancer in patients with superficial thrombophlebitis. We wanted to determine the incidence of cancer after an episode of spontaneous superficial thrombophlebitis in a large general practice population. METHODS The objective of this study was to assess the incidence of newly diagnosed malignancies in patients within 2 years after the diagnosis of a spontaneous episode of superficial thrombophlebitis and to compare this incidence with nonexposed matched control patients and the Dutch population. The patients and their controls were identified by a search in the electronic patient records of 5 primary health care centers in Amsterdam, the Netherlands. A standardized morbidity ratio was calculated using data of the Dutch cancer registry. RESULTS A total number of 277 patients with superficial thrombophlebitis were identified, of which 250 patients had no cancer at study entry. In 5 of these 250 patients (2%; 95% confidence interval [CI], 1%-5%), a new malignancy was diagnosed within 2 years after their superficial thrombophlebitis compared with 2% (95% CI, 1%-4%) in the control group. The standardized morbidity ratio was 1.1 (95% CI, 0.5-2.7). A recurrent episode of superficial thrombophlebitis was observed in 18 of the 250 patients, and in 1 patient cancer was diagnosed within 24 months after the first episode of superficial thrombophlebitis. CONCLUSION We conclude that a single episode of unprovoked superficial thrombophlebitis diagnosed by a family physician is not associated with an increased risk of subsequent cancer.