Saturday, November 13, 2010

Is it possible to avoid hypopituitarism after irradiation of pituitary adenomas by the Leksell gamma-knife?

Josef Marek, Jana Jezkova, Vaclav Hana, Michal Krsek, Lubomira Bandurova, Ladislav Pecen, Vilibald Vladyka and Roman Liscak

J Marek, 3 Dept. of Medicine, Charles University in Prague, Prague, 128 08, Czech Republic
J Jezkova, Third Dept. of Medicine, First Medical Faculty, Charles University, Praha 2, 12802, Czech Republic
V Hana, Third Dept. of Medicine, First Medical Faculty, Charles University, Praha, Czech Republic
M Krsek, Third Dept. of Medicine, First Medical Faculty, Charles University, Praha, Czech Republic
L Bandurova, Third Dept. of Medicine, First Medical Faculty, Charles University, Praha, Czech Republic
L Pecen, Institute of Informatics of the Czech Academy of Science, Praha, Czech Republic
V Vladyka, Dept. of Stereotactic and Radiation Neurosurgery, Hospital na Homolce, Praha, Czech Republic
R Liscak, Dept. of Stereotactic and Radiation Neurosurgery, Hospital na Homolce, Praha, Czech Republic

Correspondence: Jana Jezkova, Email: fjjezek@cmail.cz

Objective: Radiation therapy is one of the treatment options for pituitary adenomas. The most common side effect associated with Leksell gamma knife (LGK) irradiation is the development of hypopituitarism. The aim of this study was to verify that hypopituitarism does not develop if the maximum mean dose to pituitary is kept under 15 Gy and to evaluate the influence of maximum distal infundibulum dose on the development of hypopituitarism.

Design and methods: We followed the incidence of hypopituitarism in 85 patients irradiated with LGK in 1993-2003. The patients were divided in two subgroups: the first subgroup followed prospectively (45 patients), irradiated with a mean dose to pituitary < 15 Gy; the second subgroup followed retrospectively 1993-2001 and prospectively 2001- 2009 (40 patients), irradiated with a mean dose to pituitary > 15 Gy. Serum TSH, free thyroxine, testosterone or 17?–estradiol, IGF 1, prolactin and cortisol levels were evaluated before and every six months after LGN irradiation.

Results: Hypopituitarism after LGK irradiation developed only in one out of 45 (2.2%) patients irradiated with a mean dose to pituitary < 15 Gy, in contrast to 72.5% patients irradiated with a mean dose to pituitary >15 Gy. The radiation dose to the distal infundibulum was found as an independent factor of hypopituitarism with calculated maximum safe dose 17 Gy.

Conclusion: Keeping the mean radiation dose to pituitary under 15 Gy and the dose to the distal infundibulum under 17 Gy prevents the development of hypopituitarism following LGK irradiation.

 

From http://www.eje.org/cgi/content/abstract/EJE-10-0733v1