Screening Mammography Under Age 50
Abstract & Commentary
Synopsis: An update of recent data supports screening mammography under age 50.
Source: Antman K, Shea S. JAMA 1999;281: 1470-1472.
Antman and shea from columbia university in New York review the controversy surrounding mammography screening under age 50, and assess the results from more recent clinical trials. The promotion of mammography screening began around 1989 after the completion of the first six randomized mammography trials. In 1992, the National Cancer Institute (NCI) sponsored a conference to consider all available clinical trial data. The conference concluded that a 15-17% reduction in breast cancer mortality in women aged 40-49 years was not statistically significant. However, when the results of a controversial 1992 Canadian trial were excluded, the benefit for women aged 40-49 years was significant.
In 1997, new Swedish data indicating a significant decrease in mortality for women aged 40-49 years prompted another NCI conference. This conference was described as an "NCI brawl" in an editorial in Science.1 The controversy was fueled by the recognition that breast cancer is less frequent in younger women and a greater number of mammograms (accompanied by false positive results) are required to have an impact on breast cancer mortality.
Antman and Shea conclude that the recent data (a 24% reduction in breast cancer mortality in the Swedish trials) support mammography screening for women in their forties. However, they recommend that women without risk factors "might" begin screening between ages 45 and 50 years. They point out that there are no clinical trials providing information regarding screening for young women who have multiple first-degree relatives developing breast cancer at a young age, or in women known to carry BRCA1 or BRCA2 mutations.
COMMENT BY LEON SPEROFF, MD
It appears to me that the real issue in this controversy is cost effectiveness. The expense of mammography screening younger than age 50 is increased because of the lower frequency of breast cancer at this age and the greater difficulty of accurate mammography because of more dense breast tissue (hence, more false positive results requiring more interventions). However, this argument is derived from data based upon less advanced equipment and a time when mammograms were more expensive. Indeed, new machines using digitized computer technology will soon eliminate the problems associated with dense breasts.
Antman and Shea argue that mammography screening should begin at age 40 for women who have substantial risk factors and for women who are eager for screening. With appropriate education and support, every woman should be eager for mammography screening. Advanced equipment, lower costs, and eager women make a powerful combined argument in favor of mammography screening beginning at age 40.
False-positive mammograms leading to a large number of biopsies represent a serious obstacle, not only because of cost to the health care system, but for the individual as well in terms of stress and anxiety. All of the reviews of the mammography controversy have failed to take into account a new approach for breast cancer diagnosis. The number of unnecessary surgical procedures can be minimized by the "triple approach—," the combination of examination, mammography, and needle aspiration. The failure to detect a malignancy with at least one of the three diagnostic tests is unlikely.2
About 19% more breast cancers occur in women 40-49 than in women aged 50-59, accounting for approximately 20% of all deaths due to breast cancer.3 Furthermore, tumors in younger women grow faster; and mammography screening at a rate of less than annually will detect these tumors at a later stage of the disease. Once detected by mammography, survival expectations are the same comparing women aged 40-49 with women older than age 50 when tumors are adjusted for stage of disease.
Mammography is the most potent weapon we possess in the battle against breast cancer. Younger women should not be deprived of annual screening; indeed, the more rapid tumor growth at a younger age, combined with better technology and the triple approach, make a strong argument in favor of annual mammography screening under age 50. Until data become available, women with a first-degree relative with premenopausal breast cancer should begin annual mammography five years before the age of the relative’s initial diagnoses.
References
1. Taubes G. Science 1997;275:1056-1059.
2. Vetto J, et al. Am J Surg 1995;169:519-522.
3. American Cancer Society, www.cancer.org/statistics.html, 1998.
The following statements are true regarding breast cancer and mammography except:
a. A statistically significant decrease in breast cancer mortality has been demonstrated in the most recent clinical trials of mammography screening in women younger than age 50.
b. The "triple approach" adds ultrasonography to physical examination and mammography.
c. Breast cancers in women younger than age 50 grow faster compared with tumors in women older than age 50.
d. Breast cancers of the same stage have the same prognosis comparing women younger than age 50 with women older than age 50.
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