Nádory hypofýzy

Medical therapyCNFAs have been shown to have high affinity dopaminergic binding sites using [3H]spiperone as a radioligand with affinities similar to that seen for normal pituitary tissue and prolactinomas; however, the number of binding sites was only 18.8% of that seen in prolactinomas but similar to that seen in normal pituitaries (Bevan and Burke, 1986). In a more recent study, Pivonello et al. (2004) showed that the dopamine D2 receptor was expressed in 67% of 18 cases. Clinically, however, bromocriptine has been shown to be effective in shrinking CNFAs in less than 20% of cases (Grossman et al., 1985; Bevan and Burke, 1986; Van Schaardenburg et al., 1989). On the other hand, Greenman et al. (2005) reported giving bromocriptine to patients with CNFAs who had residual tumor on MRI following surgery, finding that the tumor mass decreased or remained stable in 18 of 20 patients. In this same study, in 13 subjects bromocriptine was started when tumor remnant growth became evident during the course of routine follow-up and this growth stabilized or decreased in 8 (62%) (Greenman et al., 2005). In contrast, tumor size increased in 29 of 47 (62%) subjects who had neither bromocriptine nor radiotherapy (Greenman et al., 2005). Cabergoline, a long-acting dopamine agonist with greater activity on prolactinomas than bromocriptine has also been found to have somewhat better in vivo activity on CNFAs. Lohmann et al. (2001) found that a > 10% (range 10–18%) tumor shrinkage in 7 of 13 patients treated with cabergoline 1 mg/week for 1 year, and Pivonello et al. (2004) found a more significant tumor size reduction (range 28.6–62.4%) in 5 of 9 patients with cabergoline 3 mg/week for 1 year. In a review of the literature, Colao et al. (2008) summarized 13 studies of patients receiving bromocriptine, finding that 8 of 128 (6.2%) patients experienced further tumor growth, 36 of 128 (28.1%) experienced tumor size reduction, and the remainder showed no change in tumor size; similarly, in three studies of patients receiving cabergoline, 3 of 23 (13%) patients experienced further tumor growth, 12 of 23 (52.2%) experienced tumor size reduction, and the remainder showed no change in tumor size. Caution is needed when using high doses of cabergoline, however, in that patients using very high doses (> 3 mg/day) for Parkinson's disease have been found to be at an increased risk for fibrotic cardiac valvular lesions (Schade et al., 2007; Zanettini et al., 2007).
Somatostatin receptors are also present in most CNFAs (De Bruin et al., 1992; Duet et al., 1994). Octreotide, a somatostatin analog, has been shown to produce a modest reduction in tumor size with improvement in visual field defects. In their review of 11 studies, Colao et al. (2008) found that visual fields improved in 27 of 84 patients (32.1%) but the changes in tumor volume were much less impressive, with tumor reduction occurring in only 5 of 100 patients, tumor increase occurring in 12 of 100 patients and no size change in the remainder. Interestingly, Andersen et al. (2001) found a 60% response rate with the combination of octreotide 200 µg three times daily subcutaneously and cabergoline 0.5 mg daily, the six responders being those who had elevated blood levels of gonadotropin subunits and the four nonresponders having no elevation of gonadotropin subunits.https://www.sciencedirect.com/topics/neuroscience/spiperone