Long-term visual changes following pituitary irradiation.

PURPOSE

To analyze possible long-term effects of pituitary irradiation on visual fields and acuity.

METHODS AND MATERIALS

Eighty-six patients were treated with radiotherapy for pituitary tumors at the National Cancer Institute between 1980 and 1991. Twenty-one patients had baseline preradiation and long-term follow-up visual fields. Eyes were followed with serial Goldmann or Humphrey visual field testing. Neuroradiologic correlation was made with the available brain scans. There were 12 females and 9 males with an median age of 44. Eighteen patients had hormone-secreting tumors and three had chromophobe adenomas. All but one patient with an inoperable invasive macroadenoma were irradiated after one or more transphenoidal resections or a craniotomy. The indications for radiation in the operable patients were: nine patients, partial tumor resection; nine patients, tumor recurrence; and two patients, persistent hormonal elevation after surgery. The median dose delivered was 50 Gy (45-59.4 Gy). The average field size was 6 x 6 cm (5 x 5 cm to 10 x 12.5 cm).

RESULTS

With a median follow-up of 48 months (14-128) after radiotherapy, 1 out of 21 patients has recurred (at 8 months) and all patients are alive. Of the 38 sighted eyes, 27 had normal visual fields before and after radiation, 7 eyes showed improvement, and 4 eyes had a stable defect, mostly in the superior temporal region. There were no cases of radiation-induced visual field or acuity deterioration. Six out of 21 patients (29%) had neurologic symptoms in follow-up, most of which appeared vascular in nature. Four patients complained of atypical migranous-like headaches that first began 1.5-3 years following treatment. One patient complained of recurrent vertical diplopia and one patient had a cerebral vascular accident 7 years following therapy. A dose-related association with these neurovascular symptoms approached statistical significance. Only 1 out of 11 (9%) patients who received doses less than or equal to 50 Gy developed these symptoms, whereas 5 out of 10 (50%) patients who received doses greater than 50 Gy developed symptoms (p2 = 0.064).

CONCLUSION

Postoperative radiation for partially resected or recurrent pituitary adenomas using megavoltage radiation, as well as modern field arrangements and fractionation, is extremely effective and safe. Ninety-five percent of patients are free of recurrence with not deterioration in the visual fields or acuities. Some patients experienced neurovascular symptoms (mostly vascular headaches) following surgery and radiation. There is a trend (p2 = 0.064) toward increased symptoms following higher radiation doses.