Breast cancer screening linked to lower stage at diagnosis, less intensive treatment

Patients who underwent breast cancer screening appeared to be diagnosed at an earlier stage and underwent less extensive medical and surgical treatment, according to a study presented at The American Society of Breast Surgeons Annual Meeting.

This association persisted among patients aged 40 to 49 years, for whom controversy exists on the necessity of screening.

“Screening mammography has been shown to significantly reduce breast cancer mortality across many different age groups, yet in 2018 compliance remains suboptimal,” Elisa Port, MD, FACS, director of the Dubin Breast Center at Mount Sinai and chief of breast cancer surgery at Mount Sinai Hospital, said during a press conference. “Recent data shows that only 60% to 70% of women who are qualified for mammography actually undergo screening mammography.

“One of the main issues is that controversies persist regarding the value of mammography and guidelines vary regarding the age to start and the frequency with which to undergo mammography, with new changes in the national guidelines in the last 2 to 3 years,” Port added.

Port and colleagues analyzed 1,125 patients diagnosed with breast cancer from September 2008 to May 2016 at a single institution. The analysis included patients aged at least 40 years with information on screening interval.

Researchers categorized patients as those who had screening within 24 months of diagnosis (73%) and those who had screening 25 or more months prior to diagnosis (27%), which included women who never had a mammogram (6%).

Patients who had been screened 25 months or more prior to cancer diagnosis appeared more likely to receive chemotherapy than those screened more recently (OR = 1.51; 95% CI, 1.14-1.99). They also appeared more likely to undergo mastectomy (OR = 1.32; 95% CI, 1-1.72) and require axillary dissection (OR = 1.66; 95% CI, 1.17-2.35) than patients who underwent screening 1 to 24 months before diagnosis.

Among patients who underwent surgery (n = 1,045), mean tumor size appeared associated with time since screening. Mean tumor size increased from 12.5 mm among those screened 1 to 24 months prior to diagnosis to 14.5 mm among those screened more than 25 months prior to diagnosis and 20 mm among those never screened.

Researchers also conducted a subgroup analysis of those aged 40 to 49 years, “because this is the group for whom the guidelines have been most controversial,” Port said.

The U.S. Preventive Services Task Force recommends screening mammography only selectively among this age group. The American Cancer Society recommends screening starting at age 45 years.

Patients aged 40 to 49 years who had never had a mammogram (n = 29) appeared more likely than those screened within 24 months of diagnosis (n = 197) to:

require chemotherapy (OR = 2.52; 95% CI, 1.1-5.77);
have positive nodes (OR = 4.52; 95% CI, 1.64-12.42);
have larger tumors (mean, 23 mm vs. 13 mm, P = .0417);
undergo mastectomy (OR = 3.44; 95% CI, 1.41-8.43); and
undergo axillary dissection (OR = 4.64; 95% CI, 2.05-10.52).

Historically, guidelines recommended breast cancer screening every year after age 40 years until patients could no longer handle mammography. However, changes in the USPSTF and American Cancer Society guidelines in 2014 and 2015 have left clinicians with inconsistency, according to Port. She recommends that women be screened every year once aged 40 years old, based on the guidelines from numerous professional societies.

“A lot of these guidelines are about cost savings,” Port said. “I worry that saving costs now by not doing as many mammograms, not doing as many biopsies and not generating as many false positives may result in cost blowup later when more women are getting chemotherapy and more women are getting more extensive surgery, not to mention personal and private costs.”

Anees B. Chagpar

Anees B. Chagpar, MD, MSc, MBA, MA, MPH, FACS, FRCS(C), associate professor of surgery at Yale University School of Medicine and assistant director of global oncology at Yale Comprehensive Cancer Center, who was not involved with the study, says these results “highlight what we already know.”

“Screening affords us the opportunity to detect cancers at an earlier stage when less aggressive treatment is possible,” Chagpar told HemOnc Today. “However, this needs to be balanced against the risks of mammography, including the fact that — particularly in younger patients — there is a lower incidence of breast cancer and the impact of screening on improving survival is less evident.” – by Cassie Homer

Reference:

Port E, et al. Impact of screening mammography interval on stage and treatment in women diagnosed with breast cancer. Presented at: The American Society of Breast Surgeons Annual Meeting; May 2-5, 2018; Orlando.

Disclosures: Port and Chagpar report no relevant financial disclosures.