Risk of haemorrhagic and ischaemic stroke in patients with cancer: a nationwide follow-up study from Sweden.

BACKGROUND

Stroke is common in cancer patients, but risk estimates for different cancer sites/types have not been determined. The aim of this nationwide study was to examine whether there is an association between cancer and first hospitalisation for haemorrhagic or ischaemic stroke.

METHODS

All 820,491 individuals in Sweden with a diagnosis of cancer between 1st January 1987 and 31st December 2008 were followed for first hospitalisation for haemorrhagic or ischaemic stroke. The reference population was the total population of Sweden without cancer. Standardised incidence ratios (SIRs) for haemorrhagic and ischaemic strokes were calculated.

RESULTS

Overall risk of haemorrhagic stroke and ischaemic stroke during the first 6 months after diagnosis of cancer was 2.2 (95% confidence interval (CI)= 2.0-2.3) and 1.6 (CI = 1.5-1.6), respectively. For 18 and 20 of the 34 cancers studied, respectively, risk of haemorrhagic and ischaemic strokes was increased. Overall stroke risk decreased rapidly, but remained elevated, even 10+years after diagnosis of cancer 1.2 (CI = 1.1-1.3) for haemorrhagic stroke and 1.1 (CI = 1.1-1.2) for ischaemic stroke. The risk of stroke was highest during the first 6 months after diagnosis of cancer of the nervous system (29 (CI = 25-34) for haemorrhagic stroke and 4.1 (CI = 3.4-4.8) for ischaemic stroke)) or leukaemia (13 (CI = 10-16) for haemorrhagic stroke and 3.0 (CI = 2.5-3.7) for ischaemic stroke)). Metastasis was associated with an increased risk of haemorrhagic stroke 2.2 (CI = 1.8-2.7) and ischaemic stroke 1.5 (CI = 1.3-1.7).

INTERPRETATION

Several cancer sites/types are associated with an increased risk of haemorrhagic and ischaemic strokes.