Shortly after the U.S. began to administer the COVID-19 vaccine, radiologists that read mammograms started to see swollen lymph nodes under the arm in which women were receiving their COVID-19 vaccine shot.

It was quickly determined these swollen lymph nodes were part of the normal germ-fighting immune system.

“The lymph node swelling is a good sign, it means your body is responding to the vaccine and building up defenses against the virus,” said Dr. Sarah Nielsen, breast imaging radiologist with Marshfield Clinic Health System. “This is not something we should be worried about.”

However, breast cancer also can present with lymph nodes that are swollen under the arm. For this reason, some women need to be evaluated further to make sure that their swollen lymph nodes are related to the vaccine and not to a new breast cancer.

“The COVID-19 vaccine does not cause breast cancer or any foreign growth,” Dr. Nielsen said. “The vaccine can simply make the mammogram harder to read for a select group of women.”

Coordinating your shot with your mammogram

For this reason, the Society of Breast Imaging recommended that women try to coordinate their mammogram and vaccine appointments by getting their mammogram before they get their vaccine.

However, if you’ve had a COVID -19 vaccination, it’s still important to keep your appointment and come in for your screening mammogram.  Make sure to let your mammogram technologist know three things that will help them interpret your mammogram images:

1. That you’ve had the vaccine
2. In which arm the vaccine was given
3. The date that the vaccine was administered

“We don’t want patients to delay getting the COVID-19 vaccine.  Women should get their COVID-19 vaccine, even if they’re scheduled to have their mammogram,” Dr. Nielsen said. “It’s important not to delay screening for breast cancer, and it’s important not to delay getting the COVID-19 vaccine.”

If your mammogram cannot be read due to the lymph node swelling, you may have to come in for another mammogram at a later date.

Advanced cases of breast cancer on the rise

Due to women holding off on mammograms during the COVID-19 pandemic, the rate of stage three and four breast cancers is on the rise.

“I have probably biopsied more lymph nodes that are positive this last year than I have in my entire career,” Dr. Nielsen said. “We’ve already seen more advanced stage cancers due to the COVID -19 virus quarantine, so we urge patients not to delay routine screening appointments any further – it’s important not to delay your health care regardless of what’s happening in the world around us.”

Dr. Nielsen also recommends that if you feel any new lump or concern you should schedule an appointment as soon as possible. Talk to your doctor for more information.

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