Effects of hydroxyapatite on spontaneous mammary tumourigenesis and related parameters in SHN virgin mice

Spontaneous mammary tumourigenesis in a high mammary tumour strain of SHN virgin mice was inhibited by the chronic ingestion of a diet containing hydroxyapatite [HAP: Ca5(OH)(PO4)3] at 2.5% or 5% up to 7 months of treatments, while not thereafter. The decrease in the excretion of urinary component levels associated with mammary tumour development was prevented in the experimental group given HAP, which resulted in the higher component levels in the experimental group than in the control of the tumourous mice. The treatment little affected body weight change, the pattern of the oestrous cycle, endocrine organ weights, glucose tolerance, serum levels of glucose and free fatty acid and serum superoxide dismutase activity. The results suggest that the inhibition by HAP of mammary tumourigenesis is at least partly ascribed to its prevention of a decreased metabolic turnover as reflected by the higher excretion of urinary components in tumourous mice given HAP.