Size reduction of extrasellar pituitary tumors during bromocriptine treatment.

The well-known size-reducing effect of bromocriptine on prolactinomas was tested on five types of large, extrasellar pituitary tumors. Twenty patients were treated prospectively for up to 4.5 years with bromocriptine, 30 or 60 mg/d (two patients received 15 mg and 160 mg, respectively). The effect on the size of the pituitary tumors was quantitated by planimetry of computed tomographic scans before and during treatment. The immediate success rate was 16 of 20 tumors. Eleven nonsecreting tumors were reduced by a median of 32% (range of reduction for 50% of cases, 18%-41%) with an immediate success rate of nine of 11. Nine secreting tumors (four that secreted prolactin; three, growth hormone; one, adrenocorticotropic hormone; and one, thyroid stimulating hormone) were reduced by a median of 51% (range of reduction for 50% of cases, 25%-72%). The reduction in tumor size was significantly associated with pretreatment size (r=0.6360, p less than 0.005), but not with the serum concentration of any hormones assayed or previous radiation treatment. Bromocriptine causes a clinically significant reduction in size of nonsecreting as well as secreting pituitary tumors with the same success rate as that of conventional treatments.U