BIOCHEMICAL PICTURE OF BONE METABOLISM IN BREAST-CANCER PATIENTS WITHBONE METASTASES

A panel of bone rum-over markers was assessed in 75 normocalcemic pati ents bearing bone metastases from breast cancer. (BC), and in 25 advan ced/metastatic BC patients without clinical appearance of bone involve ment. 225 healthy women, stratified in three subgroups according to ag e sewed as controls. Bone formation was investigated by measuring seru m carboxyterminal propeptide of type I procollagen (PICP), Bone Gla Pr otein (BGP, osteocalcin), bone isoenzyme of alkaline phosphatase (BALP ); bone resorption by measuring serum carboxyterminal telopeptide of t ype I collagen (ICTP), fasting urinary hydroxyproline/creatinine (OHPr o/Cr) and calcium/creatinine (Ca/Cr). in patients with bone metastases the pet-cent of supranormal values (higher than mean plus 2 SD of the age-matched controls) ranged between 25% and 40% for indices of bone formation, about 73% for both ICTP and OHPro/Cr and about 30% for Ca/C r: The median levels of all bone turn-over markers were higher in bone metastatic patients than in those without apparent skeletal involveme nt, but significance was attained only for OHPro/Cr, Ca/Cr and BALP. S upranormal levels of ICTP and OHPro/Cr were also found in about 65-70% of patients without apparent skeletal involvement. ICTP and Ca/Cr sig nificantly correlated with bone pain score, BALP, ICTP, Ca/Cr signific antly correlated with the number of tumour appearances in bone. In con clusion, the bone resorption indices, ICTP and OHPro/Cr were much more frequently elevated than bone formation indices in BC patients with o i. without skeletal involvement. Their potential use in the early dete ction of bone metastases is hampered by the insufficient knowledge on specificity. Among the biochemical markers evaluated, Ca/Cr, ICTP and BALP, due to correlation with clinical aspects, appear the most intere sting for follow-up studies.