'Triple negative' breast cancers linked to the young, minority
So-called "triple negative" breast cancers, tumors that do not contain any of three significant tumor markers, are aggressive, deadly cancers that affect young, poor minority women, according to a new study. Published in the May 1, 2007 issue of CANCER, a peer-reviewed journal of the American Cancer Society, the study suggests that these tumors are more common among women who are African American and Hispanic, under 40 years old, and who have lower socioeconomic status (SES). The study found triple negative tumors are also associated with later diagnosis and shorter survival.
Tumor and tissue markers provide important information, including disease type and prognosis. Three important markers in breast cancer are estrogen receptor (ER), human epidermal growth factor receptor 2 (HER2), and progesterone receptor (PR). In particular, these markers are useful in selecting appropriate adjuvant therapy and prognosis. Around 15 percent of breast cancers do not express any of these markers and are generally identified as basal-like subtypes. While these "triple negative" tumors are associated with poor prognosis and survival, hormone adjuvant therapy failure, and are often identified in African American women, little is understood about other associated demographic risk factors.
Katrina Bauer from the Public Health Institute in Sacramento, California and colleagues compared the demographic, clinical and survival characteristics of 6,370 women diagnosed with triple negative breast cancers with 44,704 women with other breast cancers.
The authors found that race and age, in particular, as well as socioeconomic status were risk factors for this type of breast cancer. Compared to Caucasians, African American women were at greatest risk followed by Hispanic women. Women under 40 years old were at greater risk than women over 60 years old. Women living in lower SES were also at higher risk compared to the highest SES.
Clinically, these tumors were more aggressive, diagnosed at more advanced stages. They were also associated with shorter survival, regardless of stage at diagnosis. African American women had the poorest five-year survival, with only 14 percent alive five years after diagnosis.
From these results, Ms. Bauer and co-authors conclude that "age less than 40 years, being non-Hispanic black and, to a lesser extent, being Hispanic, are clearly the most powerful risk factors for this poor prognosis subtype of breast cancer."