increases. An adequate dissection usually contains at least 10 lymph nodes;
however, because these tumors in 25–30% of patients with negative nodes
eventually recur, other biologic prognostic factors also are needed.
Tumor size. This correlates with the number of histologically involved lymph
nodes; however, it is also an independent prognostic factor, particularly in
node-negative women. The use of size of the tumor as the most significant
prognostic factor is problematic because 15% of patients with small tumors
have positive nodal involvement.
Receptor status. It is standard practice to determine both estrogen and
progesterone receptor status at the time of diagnosis for definitive surgical
therapy. Although hormone receptor status correlates with the prognosis, it
does so to a lesser degree than nodal status. Hormone receptor determination
is, however, of critical importance as a predictive factor. A predictive factor is
any measurement associated with response or lack of response of a particular
therapy.
Estrogen receptor status has clearly shown to be a predictive factor for
hormone therapy, either in the adjuvant therapy or the metastatic disease
setting. HER-2 (also known as HER-2.neu and c-erbB-2) is an epidermal
growth factor receptor on the surface of a cell that transmits growth signals
to the cell nucleus.
Approximately 25–30% of breast cancers overexpress HER-2, and
overexpression of the receptor is associated with poor prognosis. This may
be more of a reflection of the biologic correlates of HER-2 overexpression,
e.g., rapid tumor cell proliferation, larger tumor size, and loss of hormone
receptors, than an independent prognostic indicator.
DNA ploidy status. DNA ploidy status of tumors is determined by flow
cytometry. It measures the average DNA per cell. Tumors can be classified as
diploid with normal DNA content or aneuploid. Disease-free survival rates are