The mortality rate of black women with breast cancer is much higher than that for white women with the disease, and research is linking the reason to tumor biology.
A recent study, led by Catherine Lee at the University of Michigan Comprehensive Cancer Center, utilized the National Cancer Data Base to investigate disparities between the way the disease affects black and white American women. Most significantly, the study showed that the increased frequency of tumors that aren’t responsive to estrogen treatment in black women leads to higher mortality rates since the tumors are not amenable to hormone-based treatments. These so-called “estrogen receptor-negative tumors” are significantly more frequent in black women at every stage of diagnosis of the disease.
Each breast cancer tumor undergoes several specific analyses after it is removed. The results of these examinations enable physicians to tailor post-surgical treatment based on the patient’s particular tumor characteristics. Patients that are estrogen receptor-positive are treated with hormone-blocking agents, which can decrease the risk of relapse. Those with tumors that don’t respond to estrogen treatment do not gain any benefit from these medications, which contributes to the poorer prognosis.
“ER-negative tumors are often associated with more aggressive disease. This is most likely due to multiple other features of the tumor cells rather than being ER-negative alone,” Lee said.
Lee’s study used the National Cancer Data Base, a collaboration of the Commission on Cancer and the American Cancer Society. It is a nationwide oncology database that tracks patient characteristics, tumor staging and histology characteristics, the type of first course treatment administered, disease recurrence and survival information, according to the commission’s Web site.
The Commission on Cancer selects data from 1,400 Commission-approved programs. From these, about 70 percent of all newly diagnosed cases are reported to the national database. Since the database was started in 1989, more than 21 million cases have been documented. There are on average 950,000 new cases of cancer per year with 160,000 to 170,000 of those being breast cancer, according to Andrew Stewart, a senior manager at the database.
“The Commission on Cancer has a range of oncologists who contribute their time as advisers,” Stewart said. These doctors direct the work of the commission through committee work, and some are assigned to specific disease site teams. The site teams have the analytic support of the national database for research and focused studies, similar to Lee’s.
“The Web site has Public Benchmark reports that are available to the public,” Stewart said. “It’s a level of public reporting.” Those who go to the Commission on Cancer Web site can access these reports and select cases by year of diagnosis, site of cancer and geography. Additionally, variables such as age group, race and stage can narrow the search.
Lee’s study is rare because it used the database as a reflection of the U.S. population, which was not the original intent of this database.
“The NCDB was designed to examine cancer treatment patterns across the country. However, because of the breadth and scope of information collected, the breast cancer data is in line with a true population database,” Lee said. For this study, researchers looked at more than 170,000 cancer cases from 1998.
Other findings from the cases in the database showed that black women are diagnosed at younger ages, on average 57 years old as opposed to 62, the average age of diagnosis for white women. They are also diagnosed at more advanced stages, which is indicated by the size of the tumor and the occurrence of the disease outside of the breast, and have larger tumors.
Although Lee’s study is not the first to examine racial and socioeconomic disparities in breast cancer cases, it was done on a much larger scale than previous studies.
“Lots of people are involved in looking at disparities,” Lee said. She considers herself a minor player, indicating that the drive of others involved in the study resulted in its success.
Lee was one of six authors on the study and credits her mentor, Lisa Newman, for bringing her attention to this issue with the work she has done on racial and socioeconomic disparities in the disease.
The American Cancer Society publishes breast cancer facts and figures with findings similar to Lee’s.
Although unfamiliar with Lee’s study, Carla Kath, regional director of communications for the American Cancer Society, reiterated that black women are less likely to get breast cancer, yet more likely to die from it, which can be attributed to several factors including a lack of preventative health and more aggressive tumors.
“We actively work to understand cultural disparities and develop culturally appropriate programs and education,” Kath said.
The American Cancer Society utilizes others’ studies, along with their own, to determine where to provide resources and funding for research.
“Our biggest opportunity to step in is to provide free mammograms through health systems and try to increase early detection,” Kath said.
Breast cancer is the most frequently diagnosed non-skin cancer among women. An estimated 3,730 new cases of breast cancer are expected to be diagnosed in Missouri during 2007 along with an estimated 870 deaths from the disease, according to the American Cancer Society.
For those treating patients with breast cancer, the study will be solely educational, Lee said. She hopes other researchers will utilize this data to examine the disease on other levels.
“Hopefully it will be used as a springboard for other studies as to why this phenomenon has occurred,” she said.
Lee presented her findings Sept. 7 at the 2007 Breast Cancer Symposium in San Francisco.