ACP: Breast Cancer Screening Every 2 Years

Radiologists Cry Foul, Warn of Thousands of Deaths

Nick Mulcahy

April 09, 2019

Women with no symptoms for breast cancer should undergo mammography screening every other year, according to a new evidence-based guidance statement from the American College of Physicians (ACP), the largest medical specialty organization in the United States.

The guidance applies to women between the ages of 50 and 74 who are at "average-risk."

The statement was published online April 9 in the Annals of Internal Medicine.

"The evidence shows that the best balance of benefits and harms for these women, which represents the great majority of women, is to undergo breast cancer screening with mammography every other year," said ACP President Ana María López, MD, in a press statement. She is an internist and medical oncologist at Sidney Kimmel Cancer Center – Jefferson Health, Washington Township, New Jersey.

This approach is also endorsed by the US Preventive Services Task Force (USPSTF).

However, the new guidance drew immediate fire from the American College of Radiology (ACR) and Society of Breast Imaging (SBI).

These two radiology groups recommend women have annual mammograms starting at age 40 years and that they continue "as long as they are in good health."

In contrast, the new ACP guideline recommends mammography starting every other year starting at 50 years and stopping at 74 years. 

This "may result in up to 10,000 additional, and unnecessary, breast cancer deaths in the United States each year," the ACR and SBI comment in a joint press statement.

This approach would also "do little to nothing to address overdiagnosis or the harms of screening," they add.

New ACP Recommendations

The new ACP document is an assessment of the quality and content of seven English-language guidelines for breast cancer screening, including those from USPSTF, ACS, ACR, American College of Obstetricians and Gynecologists, Canadian Task Force on Preventive Health Care, National Comprehensive Cancer Network, and World Health Organization.

The new ACP recommendations are for women at average risk of breast cancer. This includes women without a history of breast cancer or previous diagnosis of a high-risk lesion; without genetic mutations such as BRCA1/2 or another familial breast cancer syndrome; and without a history of radiation therapy to the chest in childhood, write the guidance authors, led by Amir Qaseem, MD, PhD, of the ACP, Philadelphia, Pennsylvania.

The ACP guidance consists of four statements about mammography screening, as follows:

  • In average-risk women aged 40 to 49 years, clinicians should discuss whether to screen for breast cancer with mammography before age 50 years. Discussion should include the potential benefits and harms and a woman's preferences. Potential harms outweigh benefits in most women aged 40 to 49 years.

  • In average-risk women aged 50 to 74 years, clinicians should offer screening for breast cancer with biennial mammography.

  • In average-risk women aged 75 years or older or in women with a life expectancy of 10 years or less, clinicians should discontinue screening for breast cancer.

  • In average-risk women of all ages, clinicians should not use clinical breast examination to screen for breast cancer.

Clarity Amid Chaos

The new guidance from the ACP provides "clarity and simplicity amidst the chaos of diverging guidelines," write Joann Elmore, MD, MPH, University of California, Los Angeles, and Christoph Lee, MD, MS, University of Washington, Seattle, in an accompanying editorial.

The editorialists congratulate the ACP for their effort to clarify the multitude of breast cancer screening guidelines. However, they emphasize it is not a perfect product.

"These guidance statements...do not clearly illuminate the full path ahead for every woman," write Elmore and Lee.

For example, the pair examine the issue of breast cancer density.

The ACP considers women with dense breast tissue on mammography — and no other risk factors — to be at average risk.

"Because just under half of all women have dense tissue on mammography, this would seem reasonable," the editorialists opine.

However, "when the average risk of dense breast tissue is combined with other risk factors that also indicate average risk in isolation (such as early menarche, late menopausal onset, oral contraceptive or menopausal hormone therapy, or a single family member with a history of postmenopausal breast cancer), a woman may no longer be at average risk," they continue.

Physicians can expect that more women will inquire about breast density as a factor that increases risk beyond the average, say Elmore and Lee, as more states and even the federal government consider adding notification requirements about such density.

The editorialists emphasize that breast cancer screening guidelines are an ongoing project.

"Physicians are left to use their best judgment based on available research and expert recommendations," they summarize.

"Major Disservice"

Reacting to the news, Laurie Margolies, MD, radiologist, Mount Sinai Health System, New York City, said the new ACP guidance statements "are based on no new evidence...[and] are a major disservice to American women."

"The majority of women who are diagnosed with breast cancer are at average risk and delaying screening until age 50 will significantly delay diagnosis for many," she commented in a press statement issued by her institution.

"Hopefully, American women are smart enough to make the decision to continue yearly screening mammography," she added.

The ACR and SBI also take issue with the idea of screening every other year. In their joint press statement, the societies say that the ACP claims that "every other year mammography screening results in no significant difference in breast cancer mortality."

"This is incorrect," the societies say in their press statement. "There have been no randomized controlled trials to test this ACP claim. In fact, the NCI/CISNET models that were used by the USPSTF and the ACS actually show a major decline in deaths among women screened annually vs every other year," they comment.

Effect on Mortality

The ACP guidance notes that pooled results from meta-analyses of randomized clinical trials "demonstrated that mammography was not associated with a reduction in all-cause mortality."

In their press statement, the ACR and SBI do not address that issue of overall survival. Instead, they discuss breast cancer-associated mortality.

For example, they cite a recent study that showed women screened regularly for breast cancer have a 47% lower relative risk of dying from the disease within 20 years of diagnosis than those not regularly screened (Cancer. 2019;125:515-523).

They also cite two large studies that showed regular mammography use "cuts the risk of dying from breast cancer nearly in half."

However, other studies have suggested that the reduction in mortality is much smaller. For example, a 2014 review of 50 years of screening data, carried out by Lydia Pace, MD, MPH, and Nancy Keating, MD, MPH, both from Brigham and Women's Hospital in Boston, Massachusetts, concluded that mammography screening is associated with a 19% overall reduction of breast cancer mortality.

The ACP guidance statement authors and editorialists have reported no relevant financial relationships.

Ann Intern Med. Published online April 9, 2019.  Full text, Editorial

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