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Stroke Incidence Increases Years After Cancer Radiotherapy of the Neck: Presented at AAN

By Ed Susman

SAN FRANCISCO, CA -- April 30, 2004 -- Years after they have undergone successful radiotherapy treatment for tumours in the neck, cancer survivors appear to be at greater risk of stroke, researchers reported here April 29^th at the American Academy of Neurology 56^th Annual Meeting.

"Radiotherapy on the neck is strongly associated with an increased risk of the incidence of stroke," said Lucille Dorresteijn, MD, Neurology Resident, University Medical Center, Nijmegen, the Netherlands.

Dr. Dorresteijn speculated that because radiotherapy causes an increase in carotid-artery intima-media thickness, that narrowing of the carotid artery could be the pathogenic mechanism for the increased risk of stroke.

"The health-care system follows people after radiotherapy for cancer of [the] larynx or a parotid tumor for about 10 years, but it is after that point that the risk of stroke in these patients really begins to increase," Dr. Dorresteijn explained.

Dr. Dorresteijn said her study of 367 patients who had undergone radiotherapy of the neck for cancer indicated that after 10 years the cumulative risk of suffering a stroke was less than 5%. But after 15 years, that risk had risen to 12%, she noted. "That means this kind of stroke is fairly common for these patients," Dr. Dorresteijn added.

The retrospective chart review of the patients was performed to determine the true risk of stroke after irradiation. The researchers also sought to resolve whether the increased risk was due to accelerated atherosclerosis.

In 42 of patients treated with unilateral adjuvant radiotherapy for neck tumours, the intima-media thickness of the carotid artery was recorded by B-mode ultrasonography. Dr. Dorresteijn and colleagues compared the carotid-artery thickness on the irradiated side of the neck with the non-irradiated carotid artery. Immediately after the procedure, there was a.3-mm difference in the thickness of the intima-media on the irradiated side. After 10 years, the difference was negligible, but after 15 years the irradiated side was.67 mm thicker. This difference was significant at the P =.007 level.

A total of 14 strokes occurred in the patient group studied. Of those involving unilateral radiotherapy, 6 strokes were observed, 5 on the side of the head that was irradiated. The overall risk of stroke was 5.6%, said Dr. Dorresteijn.


Presentation title: "Cerebrovascular Disease Following Local Radiotherapy." Abstract #P06.049.

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