New Study: Dense Breasts May Modestly Increase Breast Cancer Risk

Medically reviewed by Noel Phipps, MD Florence Radiological Associates

Dense breasts were once thought to raise the risk of breast cancer so dramatically that nearly half the states have laws (NC has a law; SC is considering one) requiring a woman’s doctor to talk to her about screening in addition to mammograms.

“A study unveiled this spring, says that dense breast tissue, by itself, may modestly increase the risk of breast cancer,” says McLeod Radiologist Dr. Noel Phipps. “The underlying problem is that mammograms have trouble seeing through dense breasts to spot tumors.”


First, some basics. The term “dense breast” is not related to breast size or firmness. A woman’s breast is made of a combination of gland, fibrous and fatty tissues. If you have too little fatty tissue and too much gland and fibrous tissue, your breasts are “dense.”


Researchers at the University of California, San Francisco (UCSF) looked at the records of more than 350,000 women.

  • They found that among women aged 40-49 the rate of cancer was less than 1-in-1000, regardless of breast density.
  • About half the women with dense breast have a low risk of developing cancer.
  • And only 24% of women with dense breasts benefited from additional screening by having their cancer identified early.


When considering if you’ll be diagnosed with cancer in the next 5 years, dense breast tissue alone does not increase your risk significantly. It may be important if you have other risk factors, such as:

  • Your family history of cancer,
  • You have a BRCA 1 or 2 gene,
  • Age, because your risk of cancer increases with age.

Women can seek additional screening with an MRI or ultrasound, which can find breast cancers not seen on a mammogram. However, you should be aware that these tests return a significant number of so-called “false positives.” In other words, it says you may have a tumor, when you actually don’t, leading to even more testing and maybe even a biopsy procedure that you didn’t really need.

It’s your decision whether the additional time and expense on your part, along with a potential increase in radiation dose and emotional stress from a “false positive” is worth the additional screening information.

Also keep in mind that the recent research is only one study. Even the authors of the research suggest that more research is needed


Talk to your personal physician, OB/GYN or oncologist to find out whether they recommend additional screening. And, if you are still not comfortable, seek a second opinion.

You may also find these articles helpful:

Spotting Breast Cancer with Mammograms

Genetic Triggers for Breast Cancer

You Are the Key to Spotting Breast Cancer Early.

Have question about cancer? Click here.

To schedule your 3D mammogram at McLeod Health in Florence, Cheraw, Clarendon, Dillon, Loris or North Myrtle Beach, call (843) 777-2095 or click here.

Sources include: McLeod Health, Journal of the National Cancer Institute, Annals of Internal Medicine, American College of Radiology, American College of Obstetricians & Gynecologists