Determine the frequency and predictors of newly diagnosed cancer after an ischemic stroke (IS).

Despite the growing interest for cancer-associated strokes and suggestions of diagnostic approaches to occult cancer in patients with IS, the frequency and predictors of cancer after an IS remain unclear.

We searched eight electronic databases (including MEDLINE and EMBASE) in all languages from January 1980 to February 2019, and screened four major stroke conference proceedings. We included studies reporting data on measures of frequency, association or predictors of any malignant tumor (solid or hematological) or myeloproliferative neoplasm diagnosed after an IS, according to our published protocol (PROSPERO ID: CRD42019132455). We pooled data using random-effects model, and used Q-tests to assess for heterogeneity between subgroups.

We screened 15,400 records to include 49 in the review and 30 in the meta-analysis of frequency. The pooled cumulative incidence of cancer within 1 year after an IS was 12.3 per thousand (95% confidence interval [CI], 4.6 to 23.4). This frequency was higher in studies reporting non-neurological imaging in all subjects (41.3 per thousand; 95%CI, 9.7 to 91.8 versus 7.2 per thousand; 95%CI, 2.5 to 14.1; p=0.03) and those with cryptogenic strokes only (62.0 per thousand; 95%CI, 13.6 to 139.3 versus 8.2 per thousand; 95%CI, 3.4 to 15.0; p=0.02). The frequency of cancer appeared higher after an IS compared to controls, and most cancers were diagnosed within the first few months after the IS. We identified 22 predictors of cancer that included markers of hypercoagulability and inflammation such as higher D-dimer, C-reactive protein and fibrinogen levels.

The frequency of newly diagnosed cancer after an IS is low, but higher in cryptogenic strokes and with non-neurological imaging. Several predictors may be used to identify patients with a higher risk of cancer.