Small Increase of Metastatic Breast Cancer at First Diagnosis Seen in Young Women
Background and Reason for the Study
Young women represent a small percentage of all women diagnosed with breast cancer. They tend to have more aggressive disease than older women.
Most young women are first diagnosed with early-stage breast cancer, confined to the breast, or disease that is regional, having traveled to nearby areas such as lymph nodes or chest wall. In a metastatic diagnosis, breast cancer has spread to more distant locations, such as the bones, liver, lungs or brain.
The study researchers noted that many doctors had “a clinical impression” that more young women were being diagnosed with metastatic breast cancer than in the past. They undertook this study to see if such a trend was demonstrated by breast cancer incidence data.
This study looked at information from 1976 to 2009 for women included in the SEER (U.S. Surveillance, Epidemiology, and End Results) database, a program of the National Cancer Institute. SEER data is drawn from cancer registries in various U.S. regions.
Data was analyzed by age. One group consisted of young women, 25 to 39 years old at diagnosis. This group was compared to other, older age groups. The researchers did not include women younger than 25 in the study because there were too few cases to compare them to other age groups.
The researchers assessed stage at diagnosis, race/ethnicity, city or rural location and hormone receptor status, to see whether those factors related to receiving a metastatic diagnosis.
Over the 33-year span, the study identified 936,497 women of all ages who received a first diagnosis of metastatic breast cancer. These were not recurrences of previously diagnosed breast cancer.
Young women represented the only age group with a steady increase of metastatic diagnoses. The change was small but statistically significant (unlikely to have happened by chance):
- Incidence nearly doubled, from 1.53 per 100,000 women in 1976 to 2.9 per 100,000 in 2009
- Increase was seen in all races/ethnicities, but was statistically significant in African-American and non-Hispanic white women
- Women living in urban and non-urban locations had increase
- Metastatic breast cancer at diagnosis was higher for women with estrogen receptor-positive disease
There was no statistically significant increase in early-stage breast cancer for women of any age.
The researchers pointed out they do not yet know the reasons for the increase. They suggested it could be due to changes in staging classification, improved diagnostic imaging, the use of sentinel node biopsy to better identify higher stage disease, or other factors. It is likely there is more than one cause, they added.
The study did not examine whether, over time, aggressive disease is occurring more often in young women or whether diagnoses are being delayed by difficulty accessing care.
These findings need verification by other studies, and the researchers advised using data from countries other than the U.S.
What This Means for You
If you heard or read about this study, it might have seemed alarming. Or, perhaps, it discussed a possible trend you have wondered about.
“This study adds some important information to what we know about young women and breast cancer,” says Generosa Grana, MD, director of the Cooper Cancer Institute in Camden, N.J. “This is the first data showing an increased incidence [in young women] over time. While the increase is modest, it forces attention on this issue and highlights the need for research to understand risk factors in this population.”
Reasons for the increase were not known, but Dr. Grana says they might include dietary and environmental factors, changes in reproductive decisions or unidentified influences. She agrees that the findings need to be confirmed.
For young women already diagnosed with breast cancer, this research does not indicate any change. It says nothing about your risk of recurrence, cancer return, or spread. It only measured metastatic disease when women were first diagnosed with breast cancer.
The research highlights the need for young women not affected by breast cancer to become more aware of their risks, such as family history, Dr. Grana notes.
The study may encourage more women to see their healthcare providers promptly if they notice any change or abnormality in the normal condition of their breasts. It also alerts physicians to become better informed about breast cancer in young women. “Both of those factors might help to lessen late diagnosis,” Dr. Grana says.
To learn more about metastatic breast cancer, read one of LBBC’s free guides in the Metastatic Breast Cancer Series or visit LBBC’s website community for women living with metastatic breast cancer.
RH Johnson, FL Chien, A Bleyer. Incidence of Breast Cancer With Distant Involvement Among Women in the United States, 1976 to 2009. Journal of the American Medical Association, 2013; 309(8): 800-805.
This article was supported by Cooperative Agreement Number DP11-1111 from The Centers for Disease Control and Prevention. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the Centers for Disease Control and Prevention.