Cancer risk and subsequent survival after hospitalization for intermittent claudication.

BACKGROUND Intermittent claudication, muscle ischemia due to reduced arterial circulation, may be associated with an increased risk of cancer risk and death due to neoplasm-induced hypercoagulability and angiogenesis, or to shared risk factors, but the relation is not well understood. METHODS We conducted a population-based cohort study using the Danish National Registry of Patients to identify patients with intermittent claudication from 1980 to 2011 and no history of cancer. We followed these patients for incident cancers using the Danish Cancer Registry and compared cancer incidence among patients with intermittent claudication to that expected in the general population. We also compared the survival of patients with cancer with and without claudication, matched for sex, cancer site, stage, age at diagnosis, and diagnosis year. RESULTS A total of 53,762 patients with intermittent claudication were identified. We observed 6,270 incident cancers over a total 269,430 years of follow-up (mean, 5.0), compared with 4,306 cancer cases expected [standardized incidence ratio = 1.46; 95% confidence interval (CI), 1.42-1.49]. Cancer risk also increased after the exclusion of patients with a prior diagnosis of cerebrovascular disease, myocardial infarction, or diabetes, particularly for tobacco-related cancers. The elevated cancer risk persisted over 10 years of follow-up. For patients with cancer, diagnosis of intermittent claudication within 3 months preceding the cancer diagnosis did not influence survival, but before 3 months, was associated with modestly worse survival (mortality rate ratio = 1.19; 95% CI, 1.14-1.25). CONCLUSIONS Intermittent claudication is associated with an increased risk of cancer and poorer subsequent survival. IMPACT Clinical attention following intermittent claudication diagnosis may reveal incident cancers.