A hypothesis on the role of insulin-like growth factor I in testicular germ cell tumours

It has already been established that the growth effects of growth hormone (GH) are mediated through insulin-like growth factor I (IGF-I). Recent studies demonstrated a relationship between IGF-I levels and various types of cancer, namely colon, prostate, breast, brain and lung cancer. In addition, many experimental observations documented a participation of the IGF-I system in tumourigenesis through enhanced cell proliferation rate, antiapoptotic functions and stimulation of neovascularization. With the present known biological mechanisms, implicated in the pathogenesis of testicular germ cell tumours (GCT), it is difficult to interpret the consistently increasing incidence of this tumour over the last decades. On the other hand, unpublished data of our department are in accordance with previous published studies, suggesting that GCT may be positively associated with body height. Scattered publications report development of GCT secondary to acromegaly or long-term GH replacement therapy. Thus, it is possible that the IGF-I system may be implicated in this pathogenesis, thereby predisposing to an increased risk of testicular GCTs. If IGF-I and IGFBP-3 are found to correlate with a high incidence of testicular GCT, they might be useful surrogate markers for diagnosis and surveillance of tumour growth, and an early screening method to identify an increased risk of this type of cancer in the first degree young mate relatives of these patients. (C) 2004 Elsevier Ltd. All rights reserved.