By 2030, the number of breast cancer cases in the United States will be 50% higher than the number in 2011, according to new research from the National Cancer Institute.
In the new study, presented at the American Association for Cancer Research's annual meeting, researchers used cancer surveillance data, census data and mathematical models to arrive at projections. Part of the reason the numbers are so high, they note, is because women are living longer. Another factor is the increase in screening that enables doctors to spot and diagnose more cases of in-situ tumors—very early stage growths that may not require treatment—as well as more invasive tumors.
The data comes amid concerns about the over-treatment of breast cancer. Last year, an analysis of women with stage 1 or stage 2 breast cancer in the Journal of the National Cancer Institute found little difference in survival rates 20 years after diagnosis between women who had an unaffected breast removed and those who did not.
"There’s certainly concern, especially in the older patients, about over-diagnosis of breast cancer, and that’s one of the reasons that screening mammography can become very controversial in older patients," says Dr. Sharon Giordano, MPH, department chair of health services research at MD Anderson Cancer Center. (Giordano was not involved in the research.) "We don’t want to end up diagnosing and treating a disease that would never cause a problem during the person’s natural lifetime."
Not all in-situ breast cancer progresses into a dangerous condition, Giordano explains. "One of the unanswered questions is, how do we identify the in-situ cancers that are the ones that go on and progress to a life-threatening illness, and which are the ones that we should be leaving alone and not subjecting people to invasive surgery and radiation for treatment?"
The researchers also teased out some more hopeful projections: that the number of estrogen-receptor negative (ER-negative) cancers, the kind that don't need estrogen to grow and don't typically respond to endocrine therapy, will drop from 17% in 2011 to 9% in 2030. That may be good news, since ER-positive breast cancers tend to grow slower and have better long-term survival rates. The reasons for the expected drop aren't clear yet, the study authors say, but one contributing factor could be that women are having children later in life, and having a child young is a risk factor for ER-negative tumors.
“In sum, our results suggest that although breast cancer overall is going to increase, different subtypes of breast cancer are moving in different directions and on different trajectories,” said study author Philip S. Rosenberg, PhD, a senior investigator in cancer epidemiology and genetics at the National Cancer Institute, in a statement. “These distinct patterns within the overall breast cancer picture highlight key research opportunities that could inform smarter screening and kinder, gentler, and more effective treatment."