Chief Science Correspondent
In a study published Tuesday in the Journal of the American Medical Association, a team of researchers from Stanford University reported that breast cancer patients may not be improving their chances of long-term survival by opting for double mastectomies.
The team compiled California patient records from 1998 to 2011, noting the year of diagnosis, treatment type, survival rates and a number of other factors, including demographic information such as age, race and income level.
Using a regression analysis, the team concluded that the women who opted to remove tissue from both breasts did not have a higher survival rate than the women who chose to undergo a unilateral mastectomy or underwent other treatment options. They concluded that this preventative treatment option, which increased from 2 to 12 percent of patients during the thirteen-year sample period, may not be as effective as the patients who choose it might believe.
A mastectomy is the process of having the breast tissue removed. There are five main types of mastectomies that range from a partial mastectomy (where the cancerous tissue and part of the surrounding tissue is removed) to a radical mastectomy (where the entire breast is removed, along with the underarm lymph nodes and the chest wall muscles under the breast). Another common procedure, known as the lumpectomy, is similar to the partial mastectomy in that only part of the breast tissue is removed. Source: breastcancer.org.
However, the researchers have not provided sufficient evidence to support their claim that double mastectomies prevent the recurrence of cancer. In fact, their results actually suggest the opposite.
The study found that patients who opted to undergo a unilateral mastectomy had a significantly higher mortality rate than those who chose other treatment options, including double mastectomies. The study did not measure the number of these patients who suffered a recurrence of cancer in the unremoved breast. The team was quick to dismiss these results, saying that they likely stemmed from some unknown factor. However, as it is now, this data actually provides strong support for the benefit of double mastectomies.
Also, the researchers neglected to measure which of the patients in the study carried to breast cancer-related mutations, which significantly raise the risk of breast cancer development. Women with the BRCA1 and BRCA2 mutations have 50-65 and 45 percent chances of developing cancer by age 70, respectively, according to cancer.gov. Additionally, women either of these mutation have up to a 40 percent probability of developing a new primary breast cancer within 10 years. It is believed that these mutations account for approximately 10 percent of all breast cancers and 20 to 25 percent of all hereditary breast cancers.
A test for this mutation has been offered since the gene's discovery in 1994, although it did not become common until more recently. Genetic tests are now more a common aspect of preventative medical care. Last year, actress Angelina Jolie famously opted to undergo a double mastectomy after learning she tested positive for the BRCA1 mutation. As a result of what many call the "Angelina Jolie Effect," many women are now becoming more aware of their own genetic risks.
The researchers' reported six-fold rise in double mastectomy treatment may be a result of better awareness. Many of the patients that the study found who increasingly opted to undergo the double procedure may have done so because they knew they were predisposed to a recurrence of cancer.
Additionally, the researchers may have seen little overall benefit in double mastectomies compared to other procedures because the patients who chose it were at risk. The patients who did not opt to undergo the procedure knew that, statistically, their risks of recurrence were low. And this matches other recent studies: A paper published in July found that patients with the BRCA1 and BRCA2 mutations who underwent a double mastectomy procedure had a significantly higher survival rate.
Overall, this study lacks sufficient information to substantiate the authors' claims. Doctors should advise patients that, without a family history or genetic predisposition, the chances of recurrence are extremely low. However, current research still suggests that double mastectomies are a viable option for certain high-risk patients.