Hodgkin's survivors treated with RT have higher stroke risk

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Patients treated for Hodgkin lymphoma with radiotherapy (RT) experience a substantially increased risk of stroke and transient ischemic attack (TIA), according to a study published online June 17 in the Journal of the National Cancer Institute.

Marie L. De Bruin, PhD, from the department of epidemiology at the Netherlands Cancer Institute in Amsterdam, and colleagues quantified the long-term risk of cerebrovascular disease associated with the use of RT and chemotherapy in survivors of Hodgkin lymphoma, and explored potential pathogenic mechanisms.

The researchers performed a retrospective cohort study among 2,201 five-year survivors of Hodgkin lymphoma treated before age 51 between 1965 and 1995. They compared incidence rates of clinically verified stroke and TIA with those in the general population, and used multivariable Cox regression techniques to study treatment-related factors and other risk factors.

After a median follow-up of 17.5 years, 96 patients developed cerebrovascular disease (55 strokes, 31 TIAs, and 10 with both TIA and stroke; median age = 52 years), the authors wrote. Most ischemic events were from large-artery atherosclerosis (36 percent) or cardioembolisms (24 percent).

The standardized incidence ratio for stroke was 2.2, and 3.1 for TIA. The investigators noted that the risks remained elevated, compared with those in the general population, after prolonged follow-up.

According to De Bruin and colleagues, the cumulative incidence of ischemic stroke or TIA 30 years after Hodgkin lymphoma treatment was 7 percent.

Radiation to the neck and mediastinum delivered as part of the patients' RT was determined to be an independent risk factor for ischemic cerebrovascular disease.

The authors wrote that treatment with chemotherapy was not associated with an increased risk. Also, hypertension, diabetes mellitus and hypercholesterolemia were associated with the occurrence of ischemic cerebrovascular disease, whereas smoking and being overweight were not.

The authors acknowledged that precise information on radiation dosage was lacking in their study, and in some cases, the etiology of cerebrovascular events was unknown.

Based on their findings, De Bruin and colleagues concluded that most survivors of Hodgkin lymphoma are at increased risk for cerebrovascular events, and risk-reducing strategies should be considered.