Breast density has an impact on mammographic screening. Greater breast density results in lower sensitivity for mammography, which means more missed cancers. In some high risk patients
with greater breast density, breast ultrasound in addition to mammography, or breast MRI in addition to mammography, has been shown to detect more cancers. What we can’t
say, however, is that breast ultrasound or breast MRI in all women with dense breasts; but average risk, saves lives, or picks up more cancers earlier.
What you don’t know, is that the radiologist reading your mammogram has given you one of four results:
1. The breast is almost entirely fat (<25% glandular.)
2. There are scattered fibroglandular densities.
3. The breast tissue is heterogeneously dense, which could obscure detection of small masses.
4. The breast tissue is extremely dense. This may lower the sensitivity of mammography.
You don’t see this on your mammogram copy, but your physician does. This information may give your healthcare provider a general idea of the likelihood that cancer will be detected or missed based on your breast density.
Now, several states are currently trying to change this. The argument is that density should appear on the report sent to patients.
So, what are some of the problems with that?
Assessing breast density is difficult. When the same
radiologist, on different occasions, is given the same mammogram, differing density is often reported. Similarly, if the same mammogram is given to different radiologists, we also see differing results. If you get a report each year with a different result, that will result in confusion.
- For women with fatty breasts (the LEAST dense,) reporting this information may result in a false sense of security.
- The significance of breast density as a risk factor for breast cancer is highly controversial.
- Women who find out they have dense breasts may have undue anxiety about their risk of breast cancer, when we aren’t even sure it’s an independent risk factor.
- Including breast density results in the copy sent to the patient may result in more requests for breast ultrasound and/or breast MRI. The existing evidence does not support breast MRI or bilateral breast ultrasound in all patients with dense breasts. Doing so has been shown to increase the number of false positives, resulting in more benign breast biopsies with no known benefit.
To sum it up, ordering additional ultrasound or breast MRI on ALL women with dense breasts is not warranted. Having said that, I think women should get a copy of their breast density and be able to have the above discussion individually with their doctors.
- Dr O.