By Elizabeth Fernandez | December 19, 2011
As a woman ages, her chances of being diagnosed with a lower-risk breast tumor increase, according to a novel study led by UCSF which found that for women over 50, a substantial number of cancers detected by mammograms have good prognoses.
The study provides the first molecular evidence of an increase in low- or ultra-low-risk cancers in the tumors when detected by screening mammography. And it provides a basis for integrating molecular profiling at the time of diagnosis to help avoid overtreatment.
In their research, the UCSF scientists at the forefront of breast cancer biology, in collaboration with colleagues at the Netherlands Cancer Institute, analyzed the biology of tumors detected more than 20 years ago – before the advent of routine mammography – alongside tumors detected five years ago, after widespread screening for breast cancer was implemented. They found that mammography appears to reveal slow- to moderate-growth tumors in the population today.
The article is published in Breast Cancer Research and Treatment.
“A significant number of screen-detected tumors are very low risk,’’ said lead author Laura Esserman, MD, MBA, director of the Carol Franc Buck Breast Care Center at the UCSF Helen Diller Family Comprehensive Cancer Center. “It shows that we have an opportunity to improve care by using molecular predictors to recognize who has these ultra-low-risk or idle tumors, and safely minimize treatment.
“This information should also help inform radiologists and surgeons about how aggressive we should be in recommending biopsy for low-risk abnormalities seen on mammograms. If most of the cancer we find is low risk, then we may very well be able to test a less aggressive approach for the very low-suspicion findings on mammograms that turn out to be benign. Simple follow up may be the better approach.’’
Breast cancer rates have been on a steady rise over the past two decades, particularly among women over 50. The increase has been attributed in large measure to the widespread use of mammograms, as well as changes in population risk factors such as earlier menstruation, later pregnancies, higher alcohol consumption and, until recently, the use of hormone replacement therapy. This rate upswing has occurred in many countries that have instituted population-based screening, but whether it reflects an actual increase in low-risk tumors or the detection of harmless tumors – or both – has been unclear, the researchers say.