The American College of Obstetricians and Gynecologists (ACOG) has updated its breast cancer screening guidelines, recommending that individuals at an average risk for breast cancer initiate mammography screening at age 40. This change reflects evolving evidence that starting earlier screening yields greater net benefits in reducing breast cancer mortality, particularly for certain racial groups with higher risk factors.
Breast cancer is the second leading cause of cancer deaths in American women overall and the leading cause of cancer deaths among Black and Hispanic women. Although mammography has long been recognized as a life-saving tool by detecting cancer early, there has been debate on when screening should begin due to concerns about overdiagnosis, false positives, and potential harms such as unnecessary biopsies.
Recent evidence has prompted ACOG to revise its recommendation for individuals assigned female at birth, including cisgender women, transgender men, and nonbinary individuals. This updated guidance includes individuals with dense breast tissue or a family history of breast cancer but excludes those with higher risk factors, such as a personal history of breast cancer or previous high-risk lesion on a breast biopsy, genetic mutations linked to higher cancer risk, or a history of high-dose radiation therapy to their chest at a young age.
Under the new guidelines, routine screening mammography should start at age 40 and can be performed annually or every 2 years, based on an informed, shared decision-making process that considers the benefits and potential harms of frequent screening.
Previously, ACOG recommended initiating screening between ages 40 and 50, depending on individual risk factors and preferences, with screening required by age 50 at the latest. However, several factors, including an increasing incidence of breast cancer in younger women, have influenced the decision to lower the recommended starting age.
Increasing Incidence Among Younger Women
Between 2015 and 2019, the incidence of invasive breast cancer in women aged 40-49 years increased by approximately 2% per year.
“There has been a concerning trend of increasing breast cancer diagnoses among women in their 40s, and new data shows that earlier screening could make a significant difference in decreasing breast cancer deaths,” said Eve Zaritsky, MD, FACOG, coauthor of the clinical practice update. “While screening can sometimes cause anxiety for people and even unnecessary follow-up, the benefits of diagnosing breast cancer earlier outweigh those risks enough to warrant starting to get mammograms at age 40.”
Studies commissioned by the US Preventive Services Task Force (USPSTF) show that starting mammography at age 40 provides a greater overall benefit than beginning at age 50. Early screening reduces the number of breast cancer deaths and increases life years gained when weighed against the harms of false positives, overdiagnosis, and benign biopsies.
Addressing Health Inequities
The benefits of earlier screening are expected to be particularly significant for Black women, who have disproportionately high mortality rates from breast cancer. Even though Black women have a lower overall incidence of breast cancer than White women, they have a 40% higher 5-year age-adjusted mortality rate from the disease and a 45% increased incidence of invasive breast cancer before age 50. Black women are also more likely to be diagnosed with aggressive subtypes, such as triple-negative breast cancer, which is harder to detect and treat and occurs at younger ages.
