Endocrine Abstracts

Back ground: Encouraging responses of pituitary adenomas and pituitary carcinomas to temozolomide treatment have been well described and loss of immunopositivity of O6-methyl-guanine-DNA methyltransferase (MGMT) reportedly serves a predictor of good response. Recently some nonresponsive cases, however, also appeared. We describe here our own experiences of temozolomide treatment on three aggressive pituitary tumors.

Subjects and methods: Three pituitary tumors, a prolactin producing carcinoma, a prolactin producing atypical adenoma, and a growth hormone producing atypical adenoma were treated with 25, 3, 5 cycles, respectively, of temozolomide with dose of 200 mg/m²×5 days/ month. The immunohistochemical expression of MGMT in these tumor specimens was also evaluated.

Results: All the patients well tolerated to the treatments and no serious adverse effects were recorded. The prolactin producing carcinoma with sparse positivity (8%) to MGMT responds well to the treatment until 19 cycles but recurred under the continuation of the treatment. But the prolactin producing atypical adenoma negative to MGMT and the growth hormone producing atypical adenoma with sparse positivity (5%) to MGMT did not show any response to the three cycle or five cycles of treatment.

Conclusion: Considering good tolerance to the regimen, and good response in at least one carcinoma case of our series, and prior encouraging reports, temozolomide treatment may be a choice for aggressive pituitary tumors resistant to multimodality of treatment. But, true response ratio of aggressive pituitary tumors to this treatment, predictive factors of response and escape from effect, and long term effect should be elucidated by prospective and longitudinal multicenter study.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.