October - December 2005, Volume 1, Issue 4

Coculescu M, Anghel R, Trifanescu R, Voicu D, Karavitaki N, Wass JA

The outcome of macroprolactinomas resistant to dopamine agonists

Acta Endo (Buc) 2005, 1 (4): 423-440
doi: 10.4183/aeb.2005.423

Aim: We aimed to assess the final outcome of combined therapeutic approaches in patients with macroprolactinomas that were resistant to dopamine agonists (DA).\r\nPatients: Records of patients with macroprolactinoma hospitalized in the Institute of Endocrinology, Bucharest, between 1978-2005, were reviewed. There were 29 eligible patients resistant to DA therapy (8 men and 21 women), out of 119 patients with macroprolactinomas (24.4%); age at diagnosis of the resistant patients ranged between 16-59 years (31.9 ? 2.4 years), with mean prolactin (PRL) levels 2,110.2 ? 656.6 ng/mL (range 42-16,000 ng/mL). The mean maximal tumor diameter was 2.7 ? 0.2 cm (range 1-6.8 cm).\r\nMethods: Rapid fluoroimmunoassay using Europium was used for hormonal levels; computed tomography imaging and/or MRI were used to assess tumor size. Study design: The resistance to DA drugs was evaluated using initial criteria: the lack of prolactinoma response to current daily dose of Bromocriptine (BRC) 7.5 mg/day or to Cabergoline (CAB) up to 2 mg/week for at least 6 months (step 1) or final criteria: the lack of response to high BRC doses (30 mg/day) or CAB doses between 2.5-4 mg/week for at least 6 months (step 2). The lack of response was considered if PRL levels remained above the upper normal limit (20 ng/mL) and the tumor mass size decreased by less than 50%. All resistant cases at step 1 received thereafter maximal medical therapy with DA drugs, according to step 2. Thereafter, resistant macroprolactinomas after step 2 were submitted to step 3 - high voltage radiotherapy ? surgery. Serum PRL levels and tumor size were finally evaluated 110 ? 26.5 months later (range: 6-381).\r\nResults: Outcome of medical therapy with DA (n=29): Overall, 7 out of 29 resistant macroprolactinomas (24.1%) were successfully treated by increasing BRC dose (n=5) or changing BRC to CAB (n=2). But 22/119 (18.5%) patients remained resistant to DA drugs independent of dose, duration or type of drug used. 14 patients failed to normalize PRL levels despite CAB treatment in doses up to 7 mg/week. Outcome of radiotherapy alone or combined with surgery (n=15): PRL normalization was achieved in 4 patients out of the only 7 assessed at least at 18 months after radiotherapy. Withdrawal of DA therapy revealed 2 cured cases, both after radiotherapy and surgery. Outcome of surgery: Only one patient normalized PRL levels after surgery, but she soon relapsed. Apparently, only one case of acquired resistance to DA drugs was revealed. We found that 15.1% (18/119) of the patients with macroprolactinoma did not finally normalize their serum PRL even after combined therapy approaches (DA + radiotherapy ? surgery), after 79 ? 17.4 months (range 6 to 206 months) treatment total duration and 45.4 ? 19 months (range 3 to 206 months) after radical therapies, respectively.\r\nConclusion: In summary, the resistance was successfully treated in 38% cases (11 out of 29).

Keywords: resistant macroprolactinomas, dopamine agonists, radiotherapy, acquired tumor resistance

Correspondence: Mihail Coculescu, Institute of Endocrinology, 36 Bd. Aviatorilor, 011863, Bucharest, Romania, e-mail: m.coculescu@uni-davila.ro