Phenotype and resistance patterns of 10 resistant prolactinomas / Fenotipo y patrones de resistencia de 10 prolactinomas resistentes

Background: Dopamine agonists (DA) are the first-line therapy in prolactinomas, but they fail to decrease prolactin (PRL) levels and/or tumor size in some of these tumors, which are labeled as resistant prolactinomas (RP). To date, risk factors for DA resistance are not fully understood and management of DA-RP is not well established. Methods: We retrospectively recorded clinical, biochemical and radiological features, as well as management and outcome, of all cabergoline (CAB)-RP attended at the Endocrinology department of a tertiary hospital between 1995 and 2016. CAB resistance was defined as the failure to normalize PRL (biochemical resistance, BR) or reduce tumor size by at least 50% (morphological resistance, MR) with a CAB dose up to 2 mg/week (or 3 mg/week in cases where lower doses were not tested) for at least 3 months. Results: Ten CAB-RP were found. The mean age of the cohort was 30.6 years and 50% of subjects were male. The average tumor size was 1.78 cm (80% macroadenomas). The mean maximal dose of CAB was 3.8 mg/week. Five patients showed isolated MR, four combined MR + BR and only one isolated BR. MR patients were more often males and older than MR + BR patients. Transsphenoidal surgery achieved normalization of PRL and/or disappearance of tumor in three of seven patients. At the end of follow up all patients had controlled PRL levels (with or without CAB) and most of them bore a visible although stable tumor. Conclusions: Isolated MR and combined MR + BR are the most frequent patterns of DA resistance whereas isolated BR seems to be uncommon. Our data support a high tumor size but not male gender as a risk factor for DA resistance

Contexto: Los agonistas dopaminérgicos (AD) son el tratamiento de elección de los prolactinomas, pero en algunos casos no logran normalizar los niveles de prolactina (PRL) o disminuir el tamaño del tumor, y estos casos se etiquetan como prolactinomas resistentes (PR). Los factores de riesgo de resistencia a los AD y el manejo de los PR no están bien establecidos. Métodos: Analizamos retrospectivamente las características clínicas, bioquímicas y radiológicas, así como el manejo y evolución de los PR a cabergolina (CAB) atendidos en el departamento de Endocrinología de un hospital terciario entre 1995 y 2016. La resistencia a CAB se definió como persistencia de PRL elevada (resistencia bioquímica, RB) o reducción tumoral inferior al 50% (resistencia morfológica, RM) tras al menos 3 meses de tratamiento con una dosis de CAB de hasta 2 mg/semana (o 3 mg/semana en los casos que no recibieron dosis inferiores) Resultados: Se incluyeron 10 pacientes, edad media 30.6 años, 50% varones. El tamaño medio del tumor fue 1.78 cm (80% macroadenomas) y la dosis máxima media de CAB 3.8 mg/semana. Cinco pacientes presentaron RM aislada, cuatro RM + RB y uno RB aislada. La prevalencia de sexo masculino y la edad fueron superiores en el grupo RM comparado con el grupo RM + RB. La cirugía transesfenoidal logró normalización de PRL y/o desaparición del tumor en tres de siete pacientes. Al final del seguimiento la PRL era normal (con o sin CAB) en todos los casos y la mayoría presentaba un tumor visible de tamaño estable. Conclusiones: la RM aislada y la RM+RB combinadas son los patrones más frecuentes de resistencia a los AD. Nuestros datos apoyan la asociación del tamaño tumoral pero no del sexo masculino con la resistencia a los AD

Phenotype and resistance patterns of 10 resistant prolactinomas.

BACKGROUND: Dopamine agonists (DA) are the first-line therapy in prolactinomas, but they fail to decrease prolactin (PRL) levels and/or tumor size in some of these tumors, which are labeled as resistant prolactinomas (RP). To date, risk factors for DA resistance are not fully understood and management of DA-RP is not well established. METHODS: We retrospectively recorded clinical, biochemical and radiological features, as well as management and outcome, of all cabergoline (CAB)-RP attended at the Endocrinology department of a tertiary hospital between 1995 and 2016. CAB resistance was defined as the failure to normalize PRL (biochemical resistance, BR) or reduce tumor size by at least 50% (morphological resistance, MR) with a CAB dose up to 2mg/week (or 3mg/week in cases where lower doses were not tested) for at least 3 months. RESULTS: Ten CAB-RP were found. The mean age of the cohort was 30.6 years and 50% of subjects were male. The average tumor size was 1.78cm (80% macroadenomas). The mean maximal dose of CAB was 3.8mg/week. Five patients showed isolated MR, four combined MR+BR and only one isolated BR. MR patients were more often males and older than MR+BR patients. Transsphenoidal surgery achieved normalization of PRL and/or disappearance of tumor in three of seven patients. At the end of follow up all patients had controlled PRL levels (with or without CAB) and most of them bore a visible although stable tumor. CONCLUSIONS: Isolated MR and combined MR+BR are the most frequent patterns of DA resistance whereas isolated BR seems to be uncommon. Our data support a high tumor size but not male gender as a risk factor for DA resistance.