Increased risk of stroke and transient ischemic attack in survivors of Hodgkin lymphoma

Patients treated for Hodgkin lymphoma with radiation therapy have a substantially higher risk of stroke, according to a new study published June 17 online in the Journal of the National Cancer Institute.

The study was undertaken because information on clinically verified stroke and transient ischemic attack (TIA), or a "mini stroke," following Hodgkin lymphoma is limited.

In order to quantify the long-term risks, Flora E. van Leeuwen, Ph.D., of the Department of Epidemiology at the Netherlands Cancer Institute in Amsterdam, and colleagues performed a retrospective cohort study among 2,201 Hodgkin lymphoma survivors. The patients, who had survived at least 5 years from the time of diagnosis, had been treated between 1965 and 1995 before age 51. The researchers compared incidence rates of clinically verified stroke and TIA in this cohort with rates in the general population.

After a median follow-up of almost 18 years, 96 patients developed cerebrovascular disease. The incidence rate for stroke was 2.2 times the incidence in the general population. For TIA, it was 3.1. Risks also remained elevated, compared to those in the general population, after prolonged follow-up. Radiation to the neck and mediastinum was associated with increased risk, whereas chemotherapy was not.

"For young survivors of Hodgkin lymphoma, who are at especially increased risk of stroke and TIA, physicians should consider appropriate risk-reducing strategies, such as treatment of hypertension and lifestyle changes to reduce the risk of stroke and TIA," the authors write.

In an accompanying editorial, Dan L. Longo, M.D., of the National Institute on Aging, part of the National Institutes of Health in Bethesda, Md., discusses the study's contribution to the "already overwhelming evidence that radiation therapy in Hodgkin's disease is short-sighted…" He applauds the detailed medical documentation and nearly complete follow-up of the patients in the study, but notes a weakness, in that the relationship of stroke to radiation doses was not examined.

According to Longo, results of this study should affect a physician's choice of primary treatment. "Unfortunately, given the life-long increased risks of late effects that have been documented from the use of radiation therapy, we simply cannot keep exposing patients to risk without clear benefit while we wait for safety data to be produced," he writes. "With an alternative therapy at hand that is just as effective…, it is simply unjustified to keep using a toxic modality for the next 10-20 years…"

Citation: Article: De Bruin et al. Increase Risk of Stroke and Transient Ischemic Attack in 5-Year Survivors of Hodgkin Lymphoma. J Natl Cancer Inst 2009, 101: 928-937.
Editorial: Longo D. Late Effects from Radiation Therapy: The Hits Just Keep on Coming. J Natl Cancer Inst 2009, 101: 904-905.