Biology and surgical management of breast cancer

The surgical treatment of breast cancer has been a source of controversy. The controversy arises from the differences in physicians' philosophies regarding the biology of breast carcinoma. Traditionally, surgeons have emphasized the potential therapeutic value of regional lymph node dissection, maintaining that adequate loco-regional treatment is of prime concern in patients with localized tumors. On the other hand, medical oncologists have always stressed the systemic nature of cancer. However, breast cancer is a very heterogeneous disease with an enormous range of different biologic characteristics, and new information is continually becoming available on the natural history of breast cancer. Therefore, we should seek a more rational theory based on the clinical evidence which can explain the biologic characteristics of breast cancer. We have proposed a new spectrum hypothesis as follows: (a)tumor cells traverse lymphatics to lymph nodes by direct extension, and there is an orderly pattern in the early stage of lymph node metastases; (b)regional lymph nodes are able to trap tumor cells but are ineffective or incomplete barriers to tumor cell spread; (c)regional lymph nodes have biologic importance, and a positive lymph node is an indicator of a host-tumor relationship that correlates with the subsequent appearance of distant disease; (d)lymphatic and hematogenous dissemination occur not serially, but in a parallel fashion; (e)many palpable invasive breast cancers are a systemic disease, but non-invasive or minimally invasive breast cancers are likely to be a local disease; (f)early detection and treatment of in-breast cancer improves survival, but variations in regional therapy are unlikely to have a major influence on survival.