In a press release today, the American College of Obstetricians and Gynecologists announced new breast cancer screening guidelines. The College is recommending mammography screening be offered annually to women beginning at age 40. Previous guidelines recommended mammograms every one to two years starting at age 40 and annually beginning at age 50.
According to Jennifer Griffin, MD, MPH, who co-authored The College guidelines, the change in mammography screening for women beginning at age 40 is based on three factors: the incidence of breast cancer, the sojourn time for breast cancer growth, and the potential to reduce the number of deaths from it. The time period between when a breast cancer may be detected by a mammogram while it is very small and before it grows big enough to become symptomatic is known as the sojourn time. Although the sojourn time of individual cancers can vary, the greatest predictor is age. Women ages 40-49 have the shortest average sojourn time (2-2.4 years), while women ages 70-74 have the longest average sojourn time (4-4.1 years).
"Although women in their 40s have a lower overall incidence of breast cancer compared with older women, the window to detect tumors before they become symptomatic is shorter, on average," said Dr. Griffin. The five-year survival rate is 98% for women whose breast cancer tumors are discovered at their earliest stage, before they are palpable and when they are small and confined to the breast. "If women in their 40s have annual mammograms, there is a better chance of detecting and treating the cancer before it has time to spread than if they wait two years between mammograms."
The College continues to recommend annual clinical breast exams (CBE) for women ages 40 and older, and every one to three years for women ages 20-39. Additionally, The College encourages "breast self-awareness" for women ages 20 and older. Enhanced breast cancer screening, such as more frequent CBEs, annual MRI (magnetic resonance imaging), or mammograms before age 40, may be recommended for women at high risk of breast cancer. Breast MRI is not recommended for women at average risk of developing breast cancer.
According to The College, there is no consensus on the upper age limit for mammograms, although the benefits of screening declines with increasing age compared with the harms of overtreatment. Women ages 75 and older should discuss with their doctor whether to continue getting mammograms, said Dr. Griffin.
Practice Bulletin #122 "Breast Cancer Screening" is published in the August 2011 issue of Obstetrics & Gynecology.