Tumour antigens are poorly expressed, heterogeneous and they modulate rapidly. As a result, their recognition and elimination by the immune system is very difficult. There are several mechanisms, by means of which, the host can neutralize oncogenesis and prevent it from occurring.

The sentinel lymph node concept has brought about a revolution in the surgical treatment of the regional lymphatic basin while preserving the prognostic value of the regional lymph node status in breast cancer.

This prospective study included 93 women with early breast cancer with initial indication for surgery in whom the sentinel lymph node technique was employed. Cell immune response was assessed prior to surgery by means of in vitro mononuclear cells blastic transformation assay (BLT), of immunoglobulin (Ig) and interleukin 2 (IL-2) measurements.

The results were correlated with tumour size, presence of positive sentinel lymph node, tumour proliferation and growth markers (Ki-67, c-erbB2, bcl-2).

Even in its less advanced stages, breast cancer is more aggressive and associates with an increased rate of sentinel lymph node metastases in patients below 50 years old, the tumour size exceeds 20 mm, with the presence of peritumoral lymphocytic infiltrate, positive Ki-67 and bcl-2, an alteration of T helper (Th) lymphocytes function, increased immune suppression through IL-2 decrease, signalled by blastic transformation indexes modifications and a drop in IL-2 production (p<0.01).