Poor Risk Assessment Limits Breast Cancer Survival
The tools are imperfect. Even so, physicians and patients are not taking advantage of practices that save lives.
In July the American Society of Clinical Oncology fortified its recommendation for chemoprevention in breast cancer, telling doctors they should discuss chemoprevention with women who are at risk for invasive breast cancer. Previously, it said doctors may discuss this therapy.
While that change is just one simple word, it presents a real challenge in the fight against breast cancer. Experts say that it appears that very few physicians are assessing risk and fewer are having meaningful discussions about the trade-offs in preventive therapy.
In addition, women are expressing concern about the potential for harm from anticancer drugs.
ASCO says more than 234,000 women will be diagnosed with breast cancer and more than 40,000 women will die from it in 2013.
The very high risk of breast cancer
The National Cancer Institute (NCI) says that based on current incidence rates, 12.4% of women in the United States will develop breast cancer. This estimate comes from the most recent report by the NCI Surveillance, Epidemiology, and End Results [SEER] Program (breast cancer statistics for the years 2007 through 2009.)
Instead of knowing the risk of developing breast cancer during their entire lifetime, many women are more interested knowing in the risk of being diagnosed with breast cancer at specific ages or in specific time periods.
The SEER report estimates the risk of developing breast cancer in 10-year age intervals. According to the NCI, this table shows the risk that a woman will be diagnosed with breast cancer during the next 10 years, starting at various ages.
Risk of developing breast cancer in the next 10 years
1 in 227
1 in 68
1 in 42
1 in 28
1 in 26
These probabilities are averages for the whole population; actual rates vary by ethnic subpopulations.
In a related development, in April, the Annals of Internal Medicine published an updated systematic review of breast cancer chemoprevention for the U.S. Preventive Services Task Force (USPSTF). That review reports on the effect of chemoprevention and the challenges to its practical use.
The effective use of chemoprevention is tied to better risk assessment processes and tools as well as expanded time and tools to support women in their decisions about preventive therapy, experts say.
Much of the attention in breast cancer is focused on appropriate use of mammography, particularly in women in their 40s, but health plans that are venturing further and further into health promotion and disease prevention also need to keep risk assessment and prevention in mind.
“Mammograms are the tool for early detection, but they are not the most effective approach to breast cancer prevention,” says Otis Brawley, MD, the chief medical officer of the American Cancer Society.
Tamoxifen was approved as preventive therapy in 1999 and raloxifene is also approved. Numerous studies indicate that these drugs reduce breast cancer risk by approximately 50%. A third agent, exemestane, achieved a 65% reduction, although it does not have FDA approval for prevention.
Despite these results and increasing advocacy for breast cancer, it is widely recognized that preventive therapy has never caught on. From 2000 to 2010 there was no overall increase in the use of tamoxifen and raloxifene as chemoprevention, according to the ASCO guideline authors, citing the National Health Interview Study.
“I don’t think we are seeing an expansion in risk assessment and prevention for breast cancer. My understanding of what is going on in primary care is that the first step, risk assessment, often is not occurring, so you never really get a chance to get to the second step of talking about ways to reduce breast cancer through medication” says Therese Bevers, MD, of the MD Anderson Cancer Center and chairwoman of the National Comprehensive Cancer Network (NCCN) Breast Cancer Risk Reduction Panel.
“It’s a challenge for primary care doctors because this is a more complex discussion, very different from measuring cholesterol and relating it to heart disease,” says Bevers. “In many cases, physicians may not have the time or complete information for a complete discussion.”
In most cases, discussion of risk and prevention starts outside an oncologist’s office. “It involves primary care doctors and gynecologists, and it’s hard to know how often this occurs,” says Marcus Neubauer, MD, medical director of McKesson Specialty Health, which supports the United States Oncology Network.
Bevers says that women themselves do not seem to be initiating more frequent discussions about risk assessment and prevention. However, “for really high-risk women there’s been a rapid increase in prophylactic bilateral mastectomy, as with Angelina Jolie,” says Bevers. “We are missing prevention opportunities with the between group, where medications play an important role.”
“There is a lot of reluctance among women to take on medication therapy to lower risk,” says Brawley.
The systematic review for the USPSTF described several studies that say that women who are at risk expressed reluctance to undertake preventive therapy, with side effects the predominant concern.
The hard numbers on prevention are also a factor. The USPSTF review says that tamoxifen and raloxifene prevented 7 to 9 cases in 1,000 women over five years, compared with placebo. Yet neither reduced breast-cancer-specific or all-cause mortality rates.
“We need to create a different mindset among women about breast cancer prevention. Cardiology has been very successful in reducing the risk for cardiac disease by controlling risk factors, and we need to figure out how to do that for breast cancer,” says Bevers.
She says cardiologists have been able to get people to understand the factors related to cardiovascular disease, like hypertension, and people are willing to take medicine.
“The problem with most of the risk factors for breast cancer is that they are not personal, biologic changes that can be measured and where medication shows improvements in those measures. I can tell patients that their risk factors are being reduced, but I can’t show them it is happening.”
“If there is atypical ductal hyperplasia or atypical lobular hyperplasia or ductal carcinoma in situ, then you have a change in breast tissue and we are more successful in getting women to start therapy,” says Neubauer.
What we need
“What it really boils down to is that we have to do the best we can to establish a woman’s risk,” says Neubauer.
“We need better tools and those tools need to be at the molecular or proteomic level and we need to be able to show that therapy produces changes over time,” says Bevers.
The most common risk assessment tool is the NCI’s Breast Cancer Risk Assessment Tool. It asks about ductal carcinoma in situ, age, reproductive history, and cancer in the woman’s first-degree relatives. It does not include specific hereditary predispositions for breast cancer, such as inheriting a mutation in either the BRCA1 or BRCA2 gene, which are increasingly used to determine risk. About 5%–10% of breast carcinomas are hereditary, and these two genes play a major role in the hereditary susceptibility for this disease.
“The other tools we need are those that help with decision-making. They might be computerized tools that walk a woman through an understanding of her risks and her options for reducing that risk, including the benefits and harms, so the physician can focus on treatments.” Such decision-making tools have been developed, but they have not been thoroughly validated or accepted.