Cancer risk is determined by a combination of environmental factors and genetic predisposition. Recent evidence suggests that dietary and related factors such as physical activity and body size may influence cancer risk through their effects on the serum concentration of IGF-I and its binding proteins. The growth hormone (GH)/IGF-I axis is involved in both human development as well as the maintenance of normal function and homeostasis in most cells of the body. In addition to their classical role as endocrine hormones, its members regulate a wide range of biological functions such as cell proliferation, differentiation and apoptosis through paracrine and autocrine mechanisms. During cancer development this complex network regulating tissue homeostasis breaks down, with inappropriate expression of the GH/IGF-I axis making an important contribution. The increased understanding of the molecular mechanisms and signalling pathways regulated by the GH/IGF-I axis has started to provide significant insights into the aetiology, prevention and therapy for a number of common cancers.
PJ Jenkins and SA Bustin
CW le Roux, PJ Jenkins, SL Chew, C Camacho-Hubner, AB Grossman, GM Besser and JP Monson
OBJECTIVE: Epidemiological studies have shown an increased risk for prostate carcinoma in men with serum IGF-I in the upper part of the age-related reference range. Recombinant human GH (rhGH) is widely used in patients with GH deficiency, usually raising the serum IGF-I levels into the normal range: safety surveillance is therefore mandatory, with particular regard to neoplasia. The aim was to examine whether rhGH replacement in hypopituitary adults is associated with changes in serum prostate-specific antigen (PSA) as a surrogate marker of changes in prostatic growth. DESIGN AND METHODS: A prospective longitudinal study was used with a median follow-up of 22 (range 2.5-32) months, in which 41 men aged over 50 years with adult onset hypopituitarism and GH deficiency during rhGH replacement were examined. Serum PSA and IGF-I were measured at baseline and at latest follow-up. RESULTS: Mean serum PSA remained unchanged during rhGH replacement, with a median follow-up of 2 years. No correlation was found between the individual changes in serum IGF-I and changes in serum PSA. CONCLUSIONS: These data are reassuring thus far regarding the safety of GH replacement in relation to the prostate in this patient group.