October - December 2006, Volume 2, Issue 4

Cucu C, Anghel R, Badiu C, Dumitriu E, Hortopan D, Coculescu M

Efficacy of radiotherapy in patients with gonadotropin-expressing pituitary tumor cells in non-functioning and GH-secreting adenomas

Acta Endo (Buc) 2006, 2 (4): 419-435
doi: 10.4183/aeb.2006.419

This study evaluates the differences of radiotherapy in patients with pituitary tumors, in relation to gonadotropin immunoreactivit.\r\nDesign. It is a longitudinal, retrospective study of 117 patients submitted to pituitary surgery and high voltage radiotherapy. The excised tumors were 70 non-functioning adenomas (NFA) and 47 GH-secreting adenomas producing active acromegaly (ACM). They were evaluated before and after pituitary surgery, before radiotherapy as baseline, then at 3 different intervals at 0 - 2, 2 - 5 and > 5 years after baseline.\r\nMethods and patients. Computer tomography was used for measuring the tumor size and specific immunoassays were used for FSH, LH and nadir GH during 75 g oral glucose load. Immunohistochemistry (IHC) was performed with avidin-biotine method. High voltage conformational radiotherapy used a linear accelerator of 10 meV, with a 50 Gy on target tumor. For statistics, student&#8217; t test was used. Data before surgery (tumor volume and hormonal sexretion) were available in 70 unselected patients (31 NFA and 39 ACM from the above group). Postsurgery we defined following groups: NFA-A1 exposed to radiotherapy (n=21) and NFA-C1 unexposed to radiotherapy (n=22); ACM-A2 exposed to radiotherapy (n=20) and ACM-C2 unexposed to radiotherapy (n=10).\r\nResults. Immunohistochemistry for NFA showed 27 immunopositive for FSH or/and LH (GD+) and 40 immunonegative for FSH and LH (GD-), 3 undetermined, while for ACM were 12 GD+, 33 GD-, 2 undetermined. Immunohistochemistry data on defined groups was as follows: NFA-A1 (n=21: 12 GD+, 9 GD-) and NFA-C1 (n=22: 6 GD+, 16 GD-); ACM-A2 (n=20: 4 GD+, 16 GD-) and ACM-C2 (n=10: 3 GD+, 7 GD-). In patients with NFA presented before therapy, there are not significant differences of tumor sizes or of the levels of FSH/LH between GD+ and GD- adenomas. In ACM, before any therapy, the GD+ patients showed a significantly higher FSH levels (20.7+11.4 U/L, n=6) than GD- patients (FSH 6.6+1.6 U/L, n=22, p< 0.05) and a nonsignificant lower serum GH levels (15.1+3.5 ng/mL, n=8 versus 33.5+8.9 ng/mL, n=30 p=0.06), although the tumor size was similar between the two groups. Radiotherapy upon NFA: GD+ adenomas did not decrease their volume after radiotherapy (cranio-caudal diameter 1.63+0.79 cm, before and 1.54+0.68 cm at 2 - 5 years post-radiotherapy n=6, p= NS), in contrast with GD- tumors in which a slightly, but significant decrement in volume could be demonstrated (from 2.79+0.53 cm to 2.43+0.31 cm at 2 - 5 years, n=5, p= 0.01). Radiotherapy in ACM resulted in a decrement of serum GH level and tumor size, as compared with the control group without radiotherapy. The effect was maximal at the interval of 2-5 years. The ACM, GD- tend to respond better to radiotherapy, (i.e. GH levels decreased from 15.1+5.4 to 6.6+2.4 ng/ml at 2-5 years, p=0.05), while in patients with ACM, GD+ the GH level did not show a significant decrease (serum GH was 7.3+3.3 ng/ml before and 5.1+4 ng/mL at 2-5 years post-radiotherapy, p = NS). The CC diameter of GD- decreased from 1.1+0.3 to 0.7+0.2 at 2-5 years, p=.059, while in GD+: from 1.64+0.4 to 1.2+0.3 ng/mL at 2-5 years, p = NS.\r\nConclusion. Pituitary adenomas, both NFA and ACM that contain gonadotropin immunoreactive cells tend to be more radioresistant than those without gonadotroph cells.

Keywords: pituitary adenomas, gonadotropins, radiotherapy, immunohistochemistry

Correspondence: Mihai Coculescu, Endocrinology Department, &#8220;Carol Davila&#8221; University of Medicine and Pharmacy, 34-36 Bd. Aviatorilor, 011863, Bucharest, Romania, Phone/Fax: + 4021 3198718, e-mail: m.coculescu@uni-davila.ro