Women who are diagnosed with breast cancer at a young age, or at an advanced stage at any age, are more likely to die from the disease than from all other causes of death combined, according to a new study by scientists at the National Cancer Institute.
In the September 1 issue of the Journal of the National Cancer Institute, the NCI researchers report that the probability of death from breast cancer varies greatly according to stage, tumor size, estrogen receptor (ER) status, and age at diagnosis in both blacks and whites.
"To our knowledge, this study is the first comprehensive risk analysis to examine in detail both the risk of death from breast cancer and other causes following a breast cancer diagnosis," said Catherine Schairer, Ph.D., the study’s lead author and an epidemiologist in the Division of Cancer Epidemiology and Genetics at NCI. "These results can provide important prognostic information to physicians and patients, and may help in weighing the risks and benefits of various treatment options."
To calculate the probabilities of death from breast cancer vs. all other causes combined among breast cancer patients, Schairer and her colleagues analyzed data from NCI’s Surveillance, Epidemiology and End Results (SEER) Program for more than 400,000 breast cancer patients diagnosed between 1973 and 2000. They computed probabilities of death from breast cancer and all other causes combined over a 28-year follow-up period according to stage and age at diagnosis, and over an 11-year follow-up period according to tumor size and ER status for a subset of cases.
The researchers found that breast cancer patients with ER-negative tumors were more likely to die from their cancer than those patients with ER-positive tumors, and that patients with larger tumors were more likely to die from their cancer than patients with smaller tumors.
For patients diagnosed with localized breast cancer (cancer that has not spread past the breast tissue) before age 50, the probability of death from breast cancer was greater than that from all other causes. The authors found the same to be true for patients diagnosed with regional disease before age 60, or with distant disease (cancer that has spread to distant organs or distant lymph nodes) at any age.
As the age at breast cancer diagnosis increased, the risk of death from other causes increased and the risk of death from breast cancer generally decreased. However, even among older patients, death from breast cancer still accounted for a significant portion of mortality.
The researchers also found that while the probability of death from breast cancer varied greatly according to stage, tumor size, ER status, and age at diagnosis in both blacks and whites, mortality from breast cancer and other causes was generally higher in blacks than in whites even after accounting for these factors. The scientists write that these results are consistent with those of other analyses that have shown generally poorer breast cancer survival in black patients than in white patients. The NCI researchers suggest, as have other researchers, that this higher probability seen in blacks may be due to differences in treatment and to a higher prevalence of obesity and obesity-related health conditions in black patients, among other factors.
"Understanding these probabilities of death from breast cancer based on stage, tumor size, ER status and age can provide useful information for patients and physicians alike" said Schairer. "Future studies, such as similar analyses for other cancers and more in-depth analyses for breast cancer according to tumor size and hormone receptor status, could generate additional valuable tools for physicians and patients."