Researchers from 300 institutions around the world combined their efforts to discover 72 previously unknown gene mutations that lead to the development of breast cancer, according to an article on CNN.com.
Two studies describing their work published Monday in the journals Nature and Nature Genetics. The teams found 65 of the newly identified genetic variants are common among women with breast cancer. The other seven mutations predispose women to develop estrogen-receptor-negative breast cancer, which does respond to hormonal therapies. The new discoveries bring the total number of known variants associated with breast cancer to nearly 180, according to the article.
For the study, an international team of 550 researchers used the DNA from the blood samples of close to 300,000 women, about half of whom had had breast cancer, to look for genetic mutations. The BRCA1 and BRCA2 risk mutations, which are present in less than 1% of women, explain only a fraction of all inherited breast cancers, according to the article. The consortium came together to discover the other causes, outside BRCA1 and BRCA2 mutations, of breast cancer.
The researchers measured DNA at more than 10 million sites across the genome. “Because our study was so large, we could detect subtle differences between these two groups of women and be sure these differences were not due to chance,” said Peter Kraft, professor, Harvard T.H. Chan School of Public Health, a study author.
According to the article, the newly discovered mutations increase a woman’s risk of developing breast cancer by only 5% to 10%. Although the mutations are not as impactful as BRCA1 and BRCA2 defects, their contribution may be more prominent because there are many more of them. An individual woman may have two or more of these common smaller risk gene mutations, and so her risk for developing breast cancer increases due to their combined effects, according to the article.
Kraft noted that “taken together, these risk variants may identify a small proportion of women who are at 3-times increased risk of breast cancer.” Women found to have a number of these smaller risk genetic mutations, would likely benefit from earlier mammography screening.
Jacques Simard, PhD, a study author and professor and researcher at Universite Laval in Quebec City, agreed. He suggested it may be time to adapt breast cancer screening guidelines based on this information instead of basing mammography guidelines on age alone. By doing so, Simard said, “we will detect a higher number of breast cancers.”
On the treatment front
As research into breast cancer’s causes continues, so does the ongoing review of treatment modalities. Although medical research published in the New England Journal of Medicine in 2010 showed a condensed, three-week radiation course works just as well as the longer regimen, Kaiser Health News found only 48% of eligible breast cancer patients today get the shorter regimen, according to an article published Oct. 23 on STAT.com.
The study analyzed the records of 4,225 breast cancer patients treated in the first half of 2017. The data “reflect how hard it is to change practice,” said Justin Bekelman, MD, associate professor of radiation oncology at the University of Pennsylvania Perelman School of Medicine, in the STAT article.
Although there are good reasons to provide a longer course of treatment, such when a patient has undergone chemotherapy, all eligible breast cancer patients should be offered a shorter course of radiation, according to physicians. Studies show that side effects from the shorter regimen are the same or even milder than traditional therapy, and are more cost effective according to the article.
Many doctors cling to outdated practices out of habit, said Bruce Landon, MD, a professor of healthcare policy at Harvard Medical School.
“We tend in the healthcare system to be pretty slow in abandoning technology,” Landon said. “People say, ‘I’ve always treated it this way throughout my career. Why should I stop now?’”
According to the American Cancer Society, in 2017 an estimated 252,710 new cases of invasive breast cancer will be diagnosed among women (Table 1, page 1) and 2,470 cases will be diagnosed in men. In addition, 63,410 cases of in situ breast carcinoma will be diagnosed among women. Approximately 40,610 women and 460 men are expected to die from breast cancer in 2017.
Courses Related to ‘Breast Cancer’
CE722: Identifying Women at High Risk for Breast Cancer (1 contact hr)
About 249,260 new cases of breast cancer were diagnosed in women in the U.S. in 2016. While most breast cancers are sporadic events, up to 10% are thought to be attributed to a hereditary predisposition. A strong family history suggesting a genetic mutation predisposing a woman to breast cancer is certainly worth further investigation. However, additional risk factors beyond family history may increase a woman’s risk of developing the disease. Healthcare providers, such as nurses, advanced practice nurses, and physicians, must be aware of both a woman’s personal history and family history to better assess her risk of developing breast cancer. Individualized risk assessment allows the healthcare provider to have a meaningful discussion with the patient about prevention and screening.
CE667: Navigating the Breast Cancer Journey, Part 1 (1 contact hr)
Breast cancer is the most common cancer (excluding skin cancer) that women may have to face in their lifetimes. About one in eight women (12%) will have a lifetime probability of developing breast cancer. It will touch the lives of most health professionals of various disciplines, either personally or professionally. Overall, of an estimated 40,730 deaths from breast cancer in 2015, an expected 40,290 would be women and 440 would be men. The good news is that mortality rates from cancer for women continued to decline 1.4% between 2007 and 2011. A 35% decline in breast cancer mortality accounts for much of this decrease. At the same time, five-year survival rates have increased from 76% in 1975 to 92% in 2010 in whites and 62% to 80% in blacks. ACS released new breast cancer screening guidelines in October 2015 and it’s essential for healthcare providers to be informed about them. They can be excellent sources of information and support to patients and their significant others during every phase of the disease continuum. Patients may experience a high level of anxiety during the prediagnostic period. Healthcare professionals across disciplines can help these patients by keeping them informed about what to expect. This two-part series on breast cancer explains the disease, risk factors, diagnostics and treatments.