Background: High growth hormone/insulin-like growth factor-1 level may have oncogenic potential in animal experiments, and in patients with acromegaly. There are also some data suggesting the development of different neoplasms in animals after growth hormone administration and in humans upon growth hormone replacement therapy.

Objective: The general opinion is however, that growth hormone replacement therapy has no oncogenic effect, but the tumor marker levels have not been studied so far.

Methods: Nine patients participated in the study: 3 women, 6 men, aged between 21-52 years. 6 of them had multiple pituitary hormone deficiency and were on replacement therapy (thyroxine: 2, cortisone: 1, sexual steroids: 6 and desmopressin: 2 patients). The cause of growth hormone deficiency was the removal of pituitary tumor (6 patients) or craniopharyngioma (2 patients), and in 1 case the deficiency was idiopathic. The mean dose of growth hormone was 0.53 in female and 0.51 mg/day in male patients. Insulin-like growth factor-1, carcinoembryonal antigen, human choriogonadotropin hormone, alpha-fetoprotein, prostate specific antigen, tissue polypeptide antigen-M, ferritin, gastrointestinal carcinoma antigen, ovarian antigen, breast specific antigen, carcinoma antigen 50 were measured at baseline and after 3, 6 and 12 months of GH replacement.

Results: Insulin-like growth factor-1 standard deviation score increased: baseline: -4.1 +/- 0.5; 3 months: -0.3 +/- 0.3; 6 months: 0.7 +/- 0.2; 12 months: -0.2 +/- 0.6, P < 0.001 vs. baseline. The mean value of all tumor markers remained within the normal range and there was no significant increase within the normal range either.

Conclusions: The lack of increase of tumor marker levels does not indicate possible oncogenic effect of one-year GH treatment in hypopituitary adults. The authors can not draw any far-reaching conclusions because of the low patient number and the short follow-up, but the measurement of tumor marker levels may provide useful means to follow up long-term therapy and for the early diagnosis of possible occult malignancy.