Stage at Diagnosis
Fortunately, the majority of women with invasive breast cancer are diagnosed at earlier stages and will survive their disease to die of other causes. The most recent data available in the SEER registry indicates that for the period 1992–1999, 63 percent of all invasive breast cancer was localized at diagnosis, meaning that it had not spread beyond the breast, corresponding to Stage I and some Stage IIA patients with larger tumors but no axillary node involvement. Twenty-nine percent were diagnosed with regional disease, a wide spectrum of risk, ranging from a single node with cancer cells to multiple nodes that have grown through the capsule into surrounding tissue. Finally 6 percent of breast cancer is diagnosed as “distant” or Stage IV. In the SEER data, 3 percent of breast cancer is listed as “unstaged.”
It should be noted that these classifications in the SEER Summary Stage system do not take into account tumor size or other pathological features as does the American Joint Committee on Cancer (AJCC) TNM (tumor, node, metastasis) classification used by most physicians and hospitals.16
So the SEER category of “regional” encompasses at least two diagnostic categories in the AJCC TNM staging system, each of which carries a very different prognosis or risk for recurrence. For example, one recent report, using national data from 1,735 hospitals, reported Stage II five-year observed survival at 74.5 percent, while Stage III five-year observed survival was only 48.5 percent.17
These figures also vary significantly when broken down by race and age, as demonstrated by Figures 1 and 2 below. In the United States as a whole, white women are diagnosed at earlier stages, regardless of age. The disparity of later stage disease in black women can be more readily grasped visually in these two bar charts. Figure 1 illustrates stage at diagnosis for women under the age of 50, while Figure 2 illustrates stage at diagnosis for women over the age of 50. Worthy of note is that regardless of race, women under 50 are diagnosed at a later stage than the over 50 group. This may be a function of earlier detection through mammographic screening in the post-menopausal population. Younger women prior to the age of menopause often have dense, glandular breast tissue that is more difficult to visualize on mammograms. It's also important to realize that in younger women, tumor biology may be of a more aggressive and hormonally-insensitive type, a factor that may play a role in higher recurrence rates and mortality in young black women.
|Figure 1. Stage at Diagnosis for Women under age 50 (SEER data)|
|Figure 2. Stage at Diagnosis for Women over 50 (SEER data)|