On the progressive nature of tumour growth in the axillary nodes in breast cancer.

Tumour cells enter the axillary nodes by the afferent lymphatics, but little is known about their subsequent behaviour. Quantitation and localization of tumour growth in 156 nodes suggest that the establishment of tumour growth in them is not haphazard. It starts in the cortex, extending later through the medulla, and finally into the efferent nodal vessels. This systematic growth pattern is in keeping with the unfavourable prognosis in cases with efferent vascular invasion in which both cortex and medulla are involved.