The pattern of cancer in a large cohort of stroke patients.

A cohort of 113,732 stroke patients from Danish Hospital Discharge Registry were, by linkage to the Danish Cancer Registry, found to have developed a total of 5151 cases of cancer in a mean follow-up time of 2.4 years after the diagnosis of stroke. There was no excess of gastric cancer. The present findings fail to support the existence of a common, strong risk factor for stroke and gastric cancer in individuals. In the cohort, more cancer than expected was observed. In particular, a more than ten-fold increase in risk of brain tumours within the first year after stroke diagnosis was observed, suggesting some diagnostic misinterpretation of a brain tumour as a stroke. Minor excesses of cancer of other sites were also found in the first year of follow-up. They are probably due to increased medical surveillance and diagnostic misinterpretation of an underlying malignancy as an incident of cerebrovascular disease, eg through metastatic spread to the brain.