The influence of age on the DNA ploidy levels of breast tumours.

Primary tumour DNA content and estimates of cell cycle kinetic parameters were analysed by flow cytometry in 114 cases of breast cancer. Tumours were classified as: near-diploid, single aneuploid, tetraploid and greater, and multiploid (defined as having more than one aneuploid tumour cell population). No significant correlations were found between ploidy and histologic type, tumour size, lymph node involvement or receptor (oestrogen and progesterone) status. a highly significant correlation between ploidy and proliferative activity (as assessed by the percentage of cells in S phase) was observed, with near-diploid and diploid tumours being associated with a low (less than or equal to 10%) S phase fraction (P = 0.0001). A marked relationship between ploidy and patient age was also seen, with increased DNA content being associated with older patients (P = 0.025). In contrast, no patients with multiploid tumours were over 60 yr, and their age distribution was significantly different from the population as a whole (P less than 0.05), suggesting that multiploidy might be a phenomenon associated with the menopause.