Incidence of cerebral infarction after radiotherapy for pituitary adenoma.

The incidence of cerebral infarction was studied in 156 patients irradiated for treatment of pituitary adenomas. Seven patients experienced strokes at intervals of 3.2 to 14.6 years after irradiation. The observed incidence was not significantly greater than the expected value of 3.5 strokes (P = 0.078). Six strokes occurred in patients receiving equivalent doses (ED) of 1070 ret or more (observed to expected ratio 3.87, significantly elevated; P less than 0.001). Univariate log-rank analysis showed that the risk of stroke was significantly higher (P = 0.010) in patients receiving an ED of 1070 ret or more (4180 cGy/22 fractions) than those receiving lower doses. Multivariate analysis, however, demonstrated that the increased risk of stroke was associated only with increasing age (P less than 0.0001), not ED (P = 0.148). Due to these inconsistent statistical results, no definitive conclusions could be reached about the relationship between radiation dose to the pituitary and subsequent cerebral infarction.