Long-term effects of radiotherapy and bromocriptine treatment in patients with previous surgery for macroprolactinomas

The long-term effect of radiotherapy and bromocriptine treatment was retrospectively evaluated in 25 patients who had previously undergone transsphenoidal surgery for treatment of macroprolactinomas. Surgery had reduced the median serum prolactin (PRL) value from 613 micrograms/l, a reduction of 53%. Postoperative bromocriptine was administered to 21 of the 25 patients. In 14 of these patients, serum PRL values became normal or almost normal with medication. There were no radiological or ophthalmological signs of progressive tumor growth during bromocriptine treatment. Fourteen patients received postoperative radiotherapy. After withdrawal of bromocriptine in 13 of these patients an average of 7 years after radiotherapy, the median serum PRL value had further decreased by 95%. The PRL reduction was similar for all doses applied, 38 to 52 Gy. After withdrawal of bromocriptine in 8 patients not receiving radiotherapy an average of 7 years after operation, the median serum PRL level had further decreased by 75%. At follow-up, 18 additional instances of pituitary insufficiency had developed in the group receiving radiotherapy, compared with 8 cases of insufficiency in the group not receiving radiotherapy. Thus, because bromocriptine has a long-standing effect on prolactin secretion, and radiotherapy is associated with a notably high incidence of pituitary insufficiency, we propose that photon irradiation should be considered mainly for patients who are not candidates for surgical or medical treatment.