Things to know about breast imaging
- The goal of breast screening is to reduce deaths due to breast cancer by detecting breast cancer early, when treatment is more effective and less harmful.
- About 1 in 69 women will be diagnosed with invasive breast cancer in their forties.
- Seventy-five percent of women diagnosed with breast cancer have no special identifiable risk factors: screening only women with risk factors will miss the vast majority of women who will develop breast cancer.
- Magnetic resonance imaging (MRI), ultrasound, and sometimes nuclear medicine techniques, can show small breast cancers, but studies have not yet been performed to show that these techniques reduce mortality from breast cancer.
- Based on the observational studies of modern screening mammography there are 30 to 40% fewer deaths due to breast cancer among women screened with mammography than among those who do not undergo screening.
- Mammography is not perfect, and it will not benefit all women equally. Mammography detects most, but not all, breast cancers. There are downsides to mammography that most women will experience if they get regular mammograms, and these are most commonly the need for additional imaging when an abnormality is suspected, or the need for biopsy for findings that appear suspicious but turn out not to be cancer.
- The risk of causing breast cancer from the radiation of mammography is far lower than the likelihood of mammography detecting breast cancer for women aged 40 years and older.
- Major health organizations including the American Cancer Society, the American Society of Breast Disease, the American College of Obstetricians and Gynecologists, the American College of Radiology and the Society of Breast Imaging agree that starting annual mammography at age 40 saves the most lives.
- According to National Cancer Institute data, since mammography screening became widespread in the early 1990’s, the U.S. breast cancer death rate, unchanged for the previous 50 years, decreased over 30 percent. By not getting a yearly mammogram after age 40, women increase their odds of dying from breast cancer and that treatment for any advanced cancers ultimately found will be more extensive and more expensive.
Why screen at 40?
- Annual screening mammography starting at age 40 results in the greatest mortality reduction, the most lives saved and the most life years gained (LYG). This is why the American College of Radiology and Society of Breast Imaging recommend regular mammography in women 40-and-older (including 40-49).
- Breast cancer incidence increases substantially around age 40. The incidence rate for ages 40-44 is twice that for ages 35-39 (122.5 vs 59.5 per 100,000 women). For ages 45-49 it is 188.6 per 100,000 women; it continues to increase until age 80.
- One in six breast cancers occur in women aged 40-49.
- Forty percent of all the years of life saved by mammography are among women in their 40s.
- The years of life lost to breast cancer are highest for women in their 40’s.
- The largest (Hellquist et al) and longest running (Tabar et al) breast cancer screening trials in history have reconfirmed that regular mammography screening cuts breast cancer deaths by roughly a third in all women ages 40 and over (including women ages 40-49).
- The recent Pan-Canadian Mammography Study (Coldman et al) involved over 2.7 million women screened in Canada and showed an average mortality reduction of 40 percent, which was the same for women 40-49 as for older age groups.
- The U.S. Preventive Services Task Force (USPSTF) acknowledges an increase in total number of lives saved and life-years gained in women who start mammography screening in their 40’s.
- Analysis by Hendrick and Helvie published in the American Journal of Roentgenology shows that at current mammography screening rates, annual screening starting at age 40 saves approximately 6,500 more women's lives each year in the U.S. than the USPSTF recommendation of screening every other year starting at age 50.
- Annual screening results in more lives saved from breast cancer than biennial screening. USPSTF scientific review now shows annual screening beginning at age 40 provides the most lives saved.
- A study (Otto et al) published in Cancer Epidemiology, Biomarkers & Prevention shows mammography screening cuts the risk of dying from breast cancer nearly in half.
- A recent study published in Cancer showed that more than 70 percent of the women who died from breast cancer in their 40s at major Harvard teaching hospitals were among the 20 percent of women who were not being screened. Because medical science cannot determine which cancers will advance to kill a woman and which will not, all women 40 and older should be screened annually.
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