The luteinising hormone-releasing hormone analogue triptorelin with or without the aromatase inhibitor formestane in premenopausal breast cancer: effects on bone metabolism markers

Background: the combination of a luteinising hormone-releasing hormone (LH- RH) analogue and an aromatase inhibitor (AI) induces greater oestrogen supp ression than the analogue alone in premenopausal breast cancer. However. ve ry few data on the biological effects of such a combination are currently a vailable. Aim of the study: the short-term effects of treatment with the LH -RH analogue triptorelin alone or in association with the Al formestane on bone metabolism were investigated in premenopausal breast cancer. Circulati ng levels of the bone formation markers carboxy-terminal and amino-terminal propeptides of type I procollagen (PICP and PINP) and the bone resorption marker cross-linked carboxy-terminal telopeptide of type I collagen (ICTP) were assessed. In addition, serum levels of insulin-like growth factor (IGF )-1, IGF binding protein (IGFBP)-3 and interleukin 6 (IL-6) were evaluated. Patients anti methods: twenty-one patients with advanced breast cancer wer e randomly given triptorelin monthly alone (n = 10, arm A) or in combinatio n with formestane fortnightly (n = 11, arm B). Blood samples were collected over a 3-month period. Results: serum PICP and P = JP levels increased sig nificantly over time (P = 0.0065 and 0.0197 in arm A and B, respectively); no change in ICTP levels was observed. A rise in IGF-I and IGFBP-3 levels w as seen in each treatment group, but only the increase in IGF-I was signifi cant (P = 0.0138, always). The on-treatment levels of the bone turnover mar kers and IGF-system components were inversely correlated with serum oestrog ens. Neither treatment modalities significantly affected serum IL-6 levels over time. No difference in the behaviour of any of the assessed biomarkers was observed between patients with or without skeletal metastases. Conclus ion: it is worth noting that complete oestrogen depletion, at least in our case series, seems to increase only osteoblastic activity markers. The obse rved modifications appear to be related to oestrogen depletion per se rathe r than the degree of oestrogen suppression or the different therapeutic reg imen administered. (C) 2001 Elsevier Science Ltd. All rights reserved.