Think Pink, Breast Cancer Screening: MRI or Mammogram?

  “ Think Pink. “ Pink is everywhere in October, from the White House to NFL primetime, during breast cancer awareness month.  For many of us, breast cancer is very personal and we have seen the toll it takes on our loved ones.  Breast cancer is the most commonly diagnosed cancer in women, and currently the second leading cause of death in women. Men are not immune. The American Cancer Society estimates 232,340 women and 2,150 men will be diagnosed with breast cancer in 2013.   The good news is that the death rates from breast cancer have significantly decreased since 1990, due to a combination of earlier detection and improved treatment options. 

 Early detection includes both clinical breast examinations, and imaging studies including mammograms, and breast MRI.  The current American Cancer Society Guidelines for breast cancer screening include yearly mammograms starting at the age of 40, and clinical breast examinations about every 3 years for women in their 20-30’s, and yearly for women 40+ in age.  

Currently the most often discussed breast imaging studies are mammograms and breast MRI. Most women will undergo mammograms in their lifetime and many will undergo breast MRI. 

   Mammograms are the most common imaging tool used in breast cancer detection.  Full Field Digital mammograms (aka 2D digital mammograms) are safe low dose x-ray images of the breast obtained using compression, collected on digital detectors and stored on computers.   Mammograms are categorized as screening – for patients who are asymptomatic, with no breast complaints or diagnostic – for patients with a breast complaint (i.e. focal pain, lump, nipple discharge, skin changes), abnormal screening mammogram, recent history of breast cancer, and for follow up of probably benign findings. 

 Most facilities now also offer 3D mammograms or breast tomosynthesis. 3D mammograms are performed at the time of the 2D mammogram (adding 20-30 seconds to the entire examination), during which multiple images of the breast are obtained. There is a minimal increase in radiation exposure, and the levels are still considered safe.   The additional 3D images through the breast give the radiologist a “layer by layer” look through the breast, increasing fine detail and taking away the effect of overlapping tissue. The benefits of 3D mammography include improved cancer detection, with up to 20% more cancers being found and at smaller sizes/earlier stages, a reduction in the number of false positives resulting in less patient anxiety.   Recent studies have shown that 3D mammograms benefit all women, not just those with dense breasts.

 Breast MRI is a useful tool in detecting and characterizing breast disease when used in the appropriate clinical setting and in conjunction with other imaging. The examination is usually performed using intravenous contrast, with the patient lying on her stomach and the breasts in light compression.  The study takes 30-45 minutes, with both breasts being imaged.

 There is a subset of the population, approximately 2% of the women in the U.S., who is considered high risk and for whom annual screening breast MRI is recommended in addition to mammograms.

 High risk patients are defined by having a 20% or greater lifetime risk of developing breast cancer.  

A patient’s risk for breast cancer is determined by a number of factors including family history, a personal history of radiation, and genetic predisposition for breast cancer (BRCA gene mutations). A patient’s physician can determine her relative risk for breast cancer using a risk assessment model. 

 Breast MRI in patients diagnosed with breast cancer helps to determine the extent of disease. MRI has been found to detect additional tumors, not seen on other imaging tools, in up to 27% of patients and unsuspected contralateral breast tumors in up to 3-5 % of patients.  MRI can also help with determining local extension of disease into the chest wall. MRI is more accurate than mammogram, ultrasound and clinical breast examination in evaluating for residual disease following neoadjuvant  or preoperative chemotherapy. 

There are additional situations in which breast MRI can be useful, including suspicious nipple discharge, metastatic breast carcinoma with an unknown primary breast lesion, and suspected implant rupture.

Mammography and breast MRI are two of the most effective tools in the early detection of breast cancer.  Specifically, 3D mammography has increased the accuracy of mammography and breast MRI has been found to be effective as a screening tool in “high risk” patients with a greater than 20% lifetime risk for breast cancer.  To determine which imaging study is right for you, (screening vs diagnostic mammograms, MRI ) please take the time to discuss your breast health and risk assessment with your physician.  

    References: 

 ACR Practice Guideline for the Performance of Contrast-Enhanced Magnetic Resonance Imaging of the Breast (revised 2013)

  American Cancer Society Guidelines for the Early Detection of Cancer (revised 9/17/2013)