That one in eight lifetime risk of breast cancer scares all of us. And there are many women whose odds of getting this malignancy may be even greater. Should those with an elevated risk be screened with more than “just” a yearly mammogram?
A study attempting to answer this query was published in the April 4 issue of JAMA. Between April 2004 and February 2006, 2809 women at 21 sites through out the US who had an elevated cancer risk and/or dense breasts underwent a series of 3 annual screens with mammogram and ultrasound. Each test was independently given and the radiologists were blinded to the result of the prior test. After 3 rounds of both, 612 of the women consented to also undergo breast MRI. (Not everyone wanted it…breast MRI requires intravenous dye and can be a lengthy, uncomfortable exam.)
The median age of the women was 55 with a range of 25 to 91 years. Approximately 29% of the women were younger than 50 and 23% were premenopausal. Nearly 54% had a personal history of previous breast cancer. High risk women were defined as having one or more of the following: a known mutation for BRCA1 and BRCA 2, a history of prior chest radiation, a significant family history of breast cancer, a lifetime risk of over 25 % of developing breast cancer, a previous biopsy that showed atypical ductal hyperplasia, atypical lobular hyperplasia, lobular carcinoma in situ or any atypical growth that increased risk for future cancer. And finally the study included women who had demonstrated in previous mammograms an increased density in more than 25% of their breasts. (When the breast tissue is very dense, meaning the glands are not separated by fatty tissue, the mammographic image looks white, it’s hard to see white on white…and it’s the white distortions and calcifications that allow the mammographer to suspect and diagnose cancer. Moreover, dense breast are more likely to develop a malignancy.)
A total of 110 participants were diagnosed with breast cancer during the 3-year study. Thirty three (30%) were detected by mammography alone; 32 (29%) by ultrasound alone; and 9 (8%) by MRI after both mammography and ultrasound failed to detect cancer. Eleven cancers (10%) were not detected by any imaging. (The patient or physician probably found “something” during physical exam of the breast.)
What does this data mean? The researchers summarized the study by stating that supplemental ultrasound can increase cancer detection with each annual screen done in conjunction with mammography. They calculated that ultrasound adds detection of 5.3 cancers per 1000 women in the first year; 3.7 per 1000 women the second and third years, and an average of 4.3 per 1000 for each of the 3 rounds of annual screening for women who were at risk. The addition of MRI screening further increased cancer detection with a yield of 14.7 per 1000 women vs. mammogram plus ultrasound. Another way of putting it (for cost -effective reasons that are so important to the practice of medicine today): the number of screens needed to detect 1 cancer in high risk women was 127 for mammogram, 234 for supplemental ultrasound and 68 for supplemental MRI (after negative mammography plus ultrasound screening results).
They went on to state “one of the major concerns (aside from the cost, especially that of MRI) is the harm of extra testing and biopsies for women who don’t have cancer. Five percent of biopsies were prompted in the women screened with additional ultrasound. Obviously not all of them showed cancer. (This becomes a philosophical issue….. will high risk women take the chance of having an unnecessary biopsy on what turns out to be a false positive finding when there is also an increased chance of detecting cancer and treating it? )
In conclusion, the authors state that “for high -risk women unable to undergo MRI and for intermediate -risk women with dense breasts, including those with a personal history of breast cancer, this study supports the use of ultrasound in addition to mammography.”
Bottom line: Most women who are high risk for breast cancer due to a previous cancer, a strong family history of breast cancer or previous abnormal biopsies are aware of their risk and seek appropriate screening. (Or at least their physicians should.) But if you have no known risks for breast cancer, make sure you ask your doctor if your mammogram was difficult to read and/or displayed significant density. If so, you could benefit from additional ultrasound imaging. Now if only all of the insurance companies agreed… Perhaps this study will help get them to pay!