Online Extra: Breast-Cancer Screening: How to Choose
If there is one message that every breast-cancer specialist, fund raiser, and pink-ribbon seller would like to get out to women, it is the importance of regular screening. Do not assume that you need not worry about screening because your lifestyle is healthy, you've never smoked, and have no history of breast cancer in your family. Fact is, breast cancer strikes one in every seven women, and a majority of these women had no risk factors.
The good news, however, is that almost 100% of patients who catch their cancer in the early stages are assured long-term survival. Though some types of cancer screening, such as the PSA test for prostate cancer and X-rays for lung cancer, are controversial because there is little evidence that they improve survival rates, the benefits of breast-cancer screening are well established.
Almost every cancer organization, as well as the federal government, recommends that women get a base-line mammogram -- one that establishes the makeup of the individual breast -- at age 40, and then follow up every one to two years. At 50, annual screenings are recommended.
Nevertheless, a recent study found that 36% of U.S. women over 40 either never had a mammogram or had gone more than two years without one. Such neglect, says Dr. D. David Dershaw, director of breast imaging at Memorial Sloan-Kettering Cancer Center in New York, can be fatal. Breast tumors thrive on estrogen, so pre-menopausal women who are still producing estrogen should not let their vigilance lapse.
"The advantage of getting mammogram screening under age 50 is almost completely lost if you skip two years," he says. "If you skip three years, your advantage is eliminated." Even post-menopause, the advantage conferred by breast screening is greatly diminished if the frequency is reduced to every two to three years, from annually, he says.
Deciding what type of screening method to use can be confusing. Breast-cancer-detection technology has moved well beyond the self-examinations popular two decades ago. Besides the widely used X-ray mammography, there is digital mammography, ultrasound, magnetic resonance imaging (MRI), and genetic testing for certain genes associated with the disease. Deciding which of these methods is right for you depends on your age, risk profile, and the quality of the center doing the screening.
That last issue is of key importance. Several studies have shown that the experience and training levels of the radiologists reading the mammograms can make a big difference in terms of accuracy. One recent large study found that radiologists who read more than 2,500 mammograms a year were significantly more accurate than those who handled smaller volumes. It is well worth looking for a screening center that does a high volume of mammograms, even if it is not the medical center that does your other disease screening.
A new type of mammogram that uses digital imaging rather than X-ray film has been slowly gaining acceptance since the Food & Drug Administration approved its use in 2000. A study published in September's New England Journal of Medicine found that digital mammography can be more effective than X-ray based screening for women under 50 and those with dense breast tissue, found in about 35% to 40% of women.
However, digital mammograms are about four times as expensive, many insurance plans will not cover them, and only about 8% of screening centers in the U.S. offer them. Dr. Dershaw says other studies to be published at the end of October will show that the digital method offers no advantage over film for the overall population. "I don't think it makes a huge amount of difference" which test is used for most women, he says.
Beyond the digital vs. X-ray debate, other emerging screening technologies show promise. Ultrasound uses sound waves to make images of the breast tissue, while MRI uses magnetic fields. There is very limited data to support the use of these expensive methods for primary screening, but they are increasingly utilized as a follow up if a mammogram finds a possible lump. Sloan-Kettering suggests that women at the highest risk of developing breast cancer consider MRI screening annually.
Determining risk level is done by considering various lifestyle and family history factors that make up a breast cancer risk-assessment profile. That profile can be worked up with your doctor.
However, a DNA test is also available for detecting mutations on specific genes called BRCA1 and BRCA2 that, if present, significantly raise the risk of breast cancer. If a close family relative has developed breast cancer at an early age or has tested positive for these genes, it is well worth having the test. If the DNA test is positive, close monitoring of the breasts is crucial.
Screenings are not a guarantee that cancer will be detected early. Mammographies can miss 15% to 20% of tumors, although when combined with a physical examination by a doctor, the chances of a tumor going undetected drop to 5%. Monique Doyle Spencer, author of The Courage Muscle: A Chicken's Guide to Living with Cancer, says in her book that she had gone for mammograms every year and yet was still diagnosed with a very advanced-stage tumor when she was 46.
Still, she writes, "This isn't an excuse to skip your mammogram, nor is it a BITTER TIRADE that I've gone EVERY YEAR and it DID ME NO DAMN GOOD. No. It's encouragement to do self-exams and go to your annual physical and have an exam." Words, literally, to live by.
By Catherine Arnst in New York
Edited by Tzyh Ng