Breast carcinoma: periodicity in presentation of metastatic tumour growth in the axilla.

The clinical value of assessment of tumour load in the axilla in the treatment of breast cancer patients has stood the test of time. Much information is available on its extent and characteristic distribution but, in contrast, little is known of the biological factors that may control the timing of the metastatic phenomenon. There is recent circumstantial evidence that such factors may exist and this prompted the present detailed study of axillary metastases from a series of 437 consecutive cases of breast carcinoma. Evidence of such factors was found here also: the excess of micrometastases in cases coming to operation in the second half of the year was highly significant (P less than 0.001) and is consistent with a synchronized start to the metastatic process. The total metastatic pattern in the material further indicated that the process may show periods of inactivity, i.e. periods when new colonies are not recruited. Mechanisms controlling this periodicity could theoretically be light-mediated, opening up new possibilities in the development of anti-metastatic treatment regimes.