What is mammography?

Many women aren’t aware that a mammogram is actually just a low-energy x-ray of the breast. When the “mammogram” was put into use in the mid 1900’s, it was the best breast imaging tool available. But studies performed in the 1990’s and early 2000’s have shown that mammography misses cancer in over half of the women who have “dense breast tissue”. Unfortunately, many doctors still refuse to share this important information with their patients. The excuses we’ve encountered for not disclosing the limitations of mammography have ranged from “I wasn’t aware” to “I don’t want to scare patients”. The purpose of this article isn’t to engage in a philosophical debate over a patient’s right to know. Instead, I’d like to focus on the fact that there are better options available (which don’t even include the use of ionizing radiation) for patients who have dense breasts. These other testing options have long been available, and are far better than mammography at detecting cancer in women who have dense breasts. Two of the most readily available testing options include breast-ultrasound and breast-MRI. Countless studies have proven that ultrasounds and MRIs are superior to mammograms in detecting cancer in women who have dense breasts.

The problem with Mammograms vs. Dense Breasts

Cancerous tumors appear “white” on mammography images. However, dense breast tissue also appears “white” on mammography. Therefore, it can be impossible to see a white cancerous mass when it’s being obscured by dense, white breast tissue. Because mammography cannot penetrate dense breast tissue, a large percentage of the breast image will appear “whited-out” which can obscure the detection of cancer. This is why cancer is too often missed by mammography in women who have dense breasts. Even more frustrating is the fact that doctors routinely report mammography examinations in women with dense breast to be “normal” and even go as far as saying there’s “no evidence of cancer”. This isn’t a small problem as nearly half of the female population has “dense breast tissue”.

The math is simple

According to standard radiologic classifications, women who are deemed to have “extremely dense breasts” have breast tissue that is “above 75% dense”. That means that cancer can be hiding behind the 75% — to 100% — of the breast tissue which is dense. So what do radiologists mean when they say a mammogram is “normal” or “there’s no evidence of cancer” on the mammograms of patients who have dense breasts? This may come as surprise, but they don’t mean “there’s no breast cancer”. All that the radiologists are saying is that based on the areas of the breast that they can see – the areas not obscured by density – that there is no evidence of cancer in those areas. So let’s take it a step further. In patients who have extremely dense breasts, that means the radiologists are only able to see the 25% or less of the actual breast tissue which isn’t dense. In other words, what the radiologists should be saying is:  “The breast are extremely dense, but amongst the 0-25% of the tissue that is not dense, there’s no evidence of cancer there. However, there could be cancer that is being obscured in the other 75-100% of the tissue which is dense.” If radiologists made sure to inform their patients of this, you would probably not be reading this article right now, and may have had a much earlier diagnosis of breast cancer.

Dense Breast Tissue Obscures the Detection of Cancer
Seeing Cancer in Normal Breast (L) vs. Dense Breast (R)

The solution is simple, too

Breast-ultrasounds and Breast-MRIs are widely available, and can identify the cancers that would be obscured on mammograms in women who have dense breast tissue. The so-called supplemental tests are able to “see through” dense breast tissue, and can prevent a late-stage diagnosis of breast cancer in the population of women who have dense breasts.


If you, or someone you know, has dense breasts and wasn’t given the option to have supplemental cancer screening with breast-ultrasound or breast-MRI, call us for a confidential consultation at (800) 215-1003.