ORLANDO, FL-The current controversy over when to start and how often to recommend regular mammograms may be resulting in many women being diagnosed with breast cancer at a later stage, when more intensive treatment is required, a new study indicates.
Regular mammograms can result in earlier detection and less-aggressive treatment, even among women in the 40-49 age bracket, most of whom are not currently included in professional screening guidelines, said Elisa Port, MD, FACS, Chief of Breast Surgery and Director of the Dubin Breast Center at Mount Sinai Hospital in New York City.
She presented the findings at the annual meeting of the American Society of Breast Surgeons that showed current professional screening guidelines miss a significant number of women with breast cancer until it is too late for less-aggressive treatment (Abstract 403820).
She and her colleagues conducted the study to evaluate the influence of screening mammography on subsequent treatment, using a group of 819 patients over age 40, 73 percent of whom had screening within 2 years of breast cancer diagnosis and 27 percent who were screened more than 2 years before or never.
Patients who had had a mammogram within 2 years and underwent surgery had smaller tumors and were able to undergo less-aggressive treatment than women in the second group, with the largest tumors found among women who had never been screened.
Those who did not undergo regular screening were 51 percent more likely to be treated with chemotherapy, 32 percent to undergo mastectomy, and 66 percent to have axillary node dissection.
Most prior research has addressed the impact of screening on mortality, but relatively little study of how screening might affect the type of treatment required and associated costs, noted Port. "While regular mammograms unquestionably have been demonstrated to reduce mortality, this study shows that they also are associated with less-complex treatment regimens, with less risk of undesirable side effects that can diminish a survivor's ongoing quality of life."
After screening mammography became more common late in the last decades of the 20th century, compliance has plateaued in the past decade, she explained. "In 2015, only 65 percent of women over 40 had a mammogram within the prior 2 years."
The age at which women should begin regular screening has been controversial, with some experts concerned about overtreatment and false positives outweighing benefits in younger age groups.
"However, studies focusing only on reduction in mortality from screening mammography do not take into account other potential benefits of early detection such as the minimization of medical and surgical treatment patients need or receive to optimize survival rates," Port noted.
"When stratified by age, patients 40-49 years old who never had a mammogram presented with later-stage disease and required more involved treatments. This is significant because recently the age to begin screening has become a focus of controversy."
This is significant, she said, because the age for beginning screening has become controversial and, under current American Cancer Society and U.S. Preventive Services Task Force guidelines, mammography is classified as optional for many women in this age group.
Port noted, for example, that more extensive surgery to lymph nodes under the arm may cause lifelong lymphedema, a debilitating, chronic swelling of the area. The long-term side effects of chemotherapy include bone loss, heart problems, and risk of other cancers.
"With earlier diagnosis, patients may decrease their likelihood of needing these treatments and their associated risks. In addition, more extensive therapies add significantly to costs to the health care system."
Methods
The study involved two groups of patients diagnosed with breast cancer at Mount Sinai Medical Center's Dubin Breast Center from September 2008 to May 2016. Logistic regression models were used to assess the association between the groups and several clinical factors, including receipt of chemotherapy, node status, tumor size, and receipt of mastectomy or axillary dissection (AD).
Analyses of lymph node status and tumor size were stratified by whether a patient underwent upfront surgery or neoadjuvant chemotherapy. Subgroup analysis by age group was then performed.
Women ages 40-49 who never had a mammogram were more than 2.5 times more likely to require chemotherapy and undergo mastectomy, and 3.5 times more likely to have cancer with lymph node involvement, compared to those screened within 24 months. They also were characterized by larger tumor size (mean 23 mm vs. 13 mm).
In general, women who had not had a mammogram in 2 years were 1.5 times more likely than those screened within 24 months to have required chemotherapy, 1.3 times more likely to have undergone a mastectomy, and 1.6 times more likely to have required AD. Women who had never had a mammogram had the largest mean tumor size of 20 mm. Rates were similarly elevated in all age groups.
"Decision-making regarding the use of screening mammography should not only take into account survival advantage, but other endpoints including potential for less aggressive treatment," said Port.
Commentary
Panel moderator Julie Margenthaler, MD, a breast surgeon at Washington University School of Medicine in St. Louis, commented on the findings.
"While numerous studies have shown the benefits of screening mammography, these typically focus on a reduction in mortality. This is a large study that ties regular screening to hard data on the type of treatment required," she noted. "Surprisingly, we continue to see conflicting data on the benefits of screening mammography for women less than 50 years of age."
Kurt Samson is a contributing writer.