Stage of breast cancer is the most reliable indicator of prognosis (Table 17-6). Patients with disease localized to the breast and no evidence of regional spread after microscopic examination of the lymph nodes have by far the most favorable prognosis. Axillary lymph node status is the best-analyzed prognostic factor and correlates with survival at all tumor sizes. In addition, an increased number of axillary nodes involved correlates directly with lower survival rates. Estrogen and progesterone receptors are prognostic variables because patients with hormone receptor-negative tumors and no evidence of metastases to the axillary lymph nodes have a much higher recurrence rate than do patients with hormone receptor-positive tumors and no regional metastases. The histologic subtype of breast cancer (eg, medullary, lobular, colloid) seems to have little significance in prognosis once these tumors are truly invasive. Flow cytometry of tumor cells to analyze DNA index and S-phase frequency aid in prognosis. Tumors with marked aneuploidy have a poor prognosis (

Table 17-4). HER-2/neu oncogene amplification, epidermal growth factor receptors, and cathepsin D may have some prognostic value, but no markers are as significant as lymph node metastases in predicting outcome.

The mortality rate of breast cancer patients exceeds that of age-matched normal controls for nearly 20 years. Thereafter, the mortality rates are equal, though deaths that occur among breast cancer patients are often directly the result of tumor. Five-year statistics do not accurately reflect the final outcome of therapy.

When cancer is localized to the breast, with no evidence of regional spread after pathologic examination, the clinical cure rate with most accepted methods of therapy is 75% to greater than 90%. Exceptions to this generalization may be related to the hormonal receptor content of the tumor, tumor size, host resistance, or associated illness. Patients with small mammographically detected estrogen and progesterone receptor-positive tumors and no evidence of axillary spread have a 5-year survival rate greater than 95%. When the axillary lymph nodes are involved with tumor, the survival rate drops to 50-70% at 5 years and probably around 25-40% at 10 years. In general, breast cancer appears to be somewhat more malignant in younger than in older women, and this may be related to the fact that fewer younger women have ER-positive tumors.

For those patients whose disease progresses despite treatment, supportive group therapy may improve survival. As they approach the end of life, such patients will require meticulous efforts at palliative care.

_{Hayes DF: Prognostic and predictive factors for breast cancer: translating technology to oncology. J Clin Oncol 2005;23:1596.}