New guidance issued for breast screening
The American College of Obstetricians and Gynecologists (ACOG) has issued new breast cancer screening guidelines that recommend mammography screening be offered annually to women beginning at age 40.1 Previous college guidelines recommended mammograms every 1-2 years starting at age 40 and annually beginning at age 50.2
What led to the change for clinical practice? Three factors came into play, says Jennifer Griffin, MD, MPH, a physician at the Olson Center for Women's Health at the University of Nebraska Medical Center in Omaha and co-author of the college guidelines:
- the incidence of breast cancer;
- the sojourn time for breast cancer growth;
- the potential to reduce the number of deaths from it.
Sojourn time refers to the 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. While the sojourn time of individual cancers can vary, the greatest predictor is age, the practice bulletin notes. 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).3
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, notes 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," states Griffin.
More frequent screening is associated with more false-positive screens, notes Andrew Kaunitz, MD, professor and associate chair in the Obstetrics and Gynecology Department at the University of Florida College of Medicine — Jacksonville. Guidance issued by the U.S. Preventive Services Task Force guidelines in 2009 called for routine screening mammography to be deferred until women reached age 50 and for screens to be biennial.4 The 2009 guidance was based on the high rate of false positive screens and the large number of screens needed to prevent one breast cancer death for women in their 40s, Kaunitz notes.
"The new ACOG guidance acknowledges these concerns and the potential for anxiety associated with false-positive mammograms," Kaunitz states. "Nonetheless, ACOG also points out that in general, U.S. women cope well with such anxiety."
Still OK'd: clinical breast exams
The new practice bulletin carries a continued recommendation for annual clinical breast exams for women ages 40 and older and carries a recommendation for every 1-3 years for women ages 20-39.
Results from studies of clinical breast exams suggest they can help detect breast cancer early, particularly when used along with mammograms.5-10 This level of evidence leads the college to recommend that women ages 40 and older have an annual exam by their provider. Although the benefit of clinical breast exams is not as definitive for those younger than 40, the college continues to recommend that women ages 20-39 have a exam every 1-3 years.
ACOG now joins the American Cancer Society and the National Comprehensive Cancer Network in endorsing counseling on breast self-awareness, which teaches women awareness of the normal appearance and feel of their breasts. The concept of self-awareness is based on the fact that about 50% of all cases of breast cancer in women 50 and older and more than 70% of cases of cancer in women below age 50 are detected by women themselves, frequently as an incidental finding.11,12 The college encourages breast self-awareness for women ages 20 and older, and that awareness can include information on breast self-examination. Women should report any changes in their breasts to their healthcare providers.
What else is included in the bulletin? Enhanced breast cancer screening, such as more frequent clinical breast exams, annual magnetic resonance imagings, 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, the bulletin states.1
References
- American College of Obstetricians and Gynecologists. ACOG practice bulletin. Breast cancer screening. Practice Bulletin #122. Obstet Gynecol 2011; 118(2 Pt. 1):372-382.
- American College of Obstetricians and Gynecologists. ACOG practice bulletin. Clinical management guidelines for obstetrician-gynecologists. Practice Bulletin #42. Breast cancer screening. Obstet Gynecol 2003; 101:821-831.
- Smith RA, Duffy SW, Gabe R, et al. The randomized trials of breast cancer screening: what have we learned? Radiol Clin North Am 2004; 42:793806.
- U.S. Preventive Services Task Force. Screening for breast cancer: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med 2009; 151:716-726.
- Shen Y, Zelen M. Screening sensitivity and sojourn time from breast cancer early detection clinical trials: mammograms and physical examinations. J Clin Oncol 2001; 19:3,490-3,499.
- Jatoi I. Breast cancer screening. Am J Surg 1999; 177:518-524.
- Primic-Zakelj M. Screening mammography for early detection of breast cancer. Ann Oncol 1999; 10(suppl 6):121-127.
- Fletcher SW, Black W, Harris R, et al. Report of the International Workshop on Screening for Breast Cancer. J Natl Cancer Inst 1993; 85:1,644-1,656.
- Miller AB, To T, Baines CJ, et al. Canadian national breast screening study — 2: 13-year results of a randomized trial in women aged 5059 years. J Natl Cancer Inst 2000; 92:1,490-1,449.
- Chiarelli AM, Majpruz V, Brown P, et al. The contribution of clinical breast examination to the accuracy of breast screening. J Natl Cancer Inst 2009; 101:1,236-1,243.
- Coates RJ, Uhler RJ, Brogan DJ, et al. Patterns and predictors of the breast cancer detection methods in women under age 45 years of age (United States). Cancer Causes Control 2001; 12:431-442.
- Newcomer L, Newcomb P, Trentham-Dietz A, et al. Detection method and breast carcinoma histology. Cancer 2002; 95:470-477.
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