Why are Young Breast Cancer Patients More Likely to Die From Their Disease?
A New Study Finds Correlation Between Biological Subtype and Survival
FREMONT, CA (January 9, 2014) — In a recent study, researchers from the Cancer Prevention Institute of California (CPIC) found that the biological subtype of breast cancer diagnosed in adolescent and young adult women directly affects their risk of dying from the disease.
“We have known for a long time that women between the ages of 15 and 39 who have breast cancer are less likely to survive than older women with the disease,” said Theresa Keegan, Ph.D., a research scientist at CPIC and lead author of the study. “We wanted to know if the biological subtype of breast cancer had anything to do with survival differences, and we definitely found a link.”
Increasingly, scientists agree that breast cancer is comprised of important biological subtypes. These subtypes are defined by the presence(+) or absence(-) of certain molecular markers, including estrogen and progesterone hormone receptors (HR) and the human epidermal growth factor receptor 2 (HER2).
Adolescent and young adult women diagnosed with the triple-negative subtype, which has no hormone receptors or HER2 protein, were 2.7 times more likely to die from their disease, the authors reported. This subtype is the second most common and was found in 19 percent of study participants.
The researchers found that adolescent and young adult women diagnosed with the subtype HR-/HER2+ have a 1.6 times greater risk of dying from the disease than women with HR+/HER2- breast cancer, which is the most common type, present in 41 percent of study participants. Eight percent of participants had the more fatal subtype.
Race and ethnicity, socioeconomic status and insurance coverage also are contributing factors to breast cancer survival among women in this age group, the study found.
Adolescent and young adult women of black race/ethnicity have poorer survival outcomes than non-Hispanic white women of the same age. Those residing in lower socioeconomic neighborhoods or having public health insurance also had poorer survival outcomes, the authors noted.
“Previous CPIC studies have shown that young black women are more likely to be diagnosed with triple-negative breast cancer relative to young white women,” Keegan said. “Yet this does not fully explain the poorer survival rates.”
Other factors that may contribute to an unfavorable survival profile for young black women include variations in the course of treatment and level of follow-up care.
In a previous study, CPIC researchers found that women 15 to 39 years of age were more likely to be diagnosed with later stage disease, as well as the subtypes associated with poorer survival than older women, the authors noted.
“We found that after we considered stage at diagnosis, adolescent and young adult women had equivalent short-term survival to older women. Therefore, if a young woman thinks she has a breast abnormality, it is very important for her to seek medical attention. The best survival outcome comes from early detection,” Keegan noted.
CPIC researchers obtained data from the California Cancer Registry for 5,331 young women ranging in age from 15 to 39 diagnosed with breast cancer between 2005 and 2009. For comparison purposes, the researchers also evaluated data from 53,860 women between 40 and 64 years of age who had been diagnosed with breast cancer.
Further studies should consider whether breast cancer subtypes and other factors, including differences in treatment regimens, influence longer-term survival in young compared to older women, and white compared to black women, the researchers noted.
The study was supported in part by the State of California Department of Public Health, the National Cancer Institute and the Centers for Disease Control and Prevention. It has been e-published in the journal Breast Cancer Research and is pending print publication.
About the Cancer Prevention Institute of California
The Cancer Prevention Institute of California (CPIC) is the nation’s premier organization dedicated to preventing cancer and to reducing its burden where it cannot yet be prevented. CPIC tracks patterns of cancer throughout the entire population and identifies those at risk for developing cancer. Its research scientists are leaders in investigating the causes of cancer in large populations to advance the development of prevention-focused interventions. CPIC’s innovative cancer prevention research and education programs, together with the work of the Stanford Cancer Institute, deliver a comprehensive arsenal for defeating cancer. For more information, visit CPIC’s official website at www.cpic.org
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