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Published on March 09, 2021

COVID-19 vaccine can cause temporary mimic of breast cancer

Vaccine Mammogram

COVID-19 vaccine anticipation is high in the United States, so most people know the most common side effects of the shot. Those include short-term fever, headache and flu-like symptoms. But a new symptom has popped up in about 16 percent of those vaccinated: swollen lymph nodes in the armpit or neck regions.

Because enlarged lymph nodes can be an indication of breast cancer, it is causing women to fear they may have the disease. It can also be deceiving for radiologists reading mammograms, said radiologist Anne Morris, MD, who works at the Cuda Women’s Health Center in Hyannis.

“All vaccines can result in a temporary swelling in the lymph nodes,” said Dr. Morris. The lymph nodes are part of the immune system so, when they detect a foreign invader, they’re going to get bigger. It’s been seen occasionally in other vaccines, but with the COVID vaccine, it’s more common.”

Those who do experience swelling - and it can be men as well as women - usually experience it for a few days or up to a few weeks, she said.

Since breast radiologists will increasingly encounter swollen lymph nodes, or what is technically called axillary adenopathy, as vaccine rates increase, Cape Cod Healthcare radiologists who specialize in mammograms have created recommendations for patients. These recommendations follow the Society of Breast Imaging guidelines on the topic.

“For screening mammograms only, if you can you should get your mammogram before your vaccination or wait four to six weeks following the second dose of the vaccination,” Dr. Morris said.

The problem is that if radiologists see an increase in size of axillary lymph nodes on a mammogram, even if this may be vaccine-related, they have to call the patient back in for a work-up and more imaging. Even though the change could be related to the vaccine, it could also be related to something else, like metastatic cancer to the axilla or a lymphoma.

“If patients have had the vaccine and we find the lymph nodes are swollen without another cause then we usually recommend a short-term follow-up,” Dr. Morris said. “The recommendation is anywhere from 4 to 12 weeks follow-up to make sure that these lymph nodes go back to normal. But it’s better for patients that they not have to go through this process. We don’t want to cause unnecessary work-up and anxiety in women.”

Recommendations for Screening Mammograms Only

Since so many women put off mammograms due to COVID worries, many of them are just now getting back on track with screenings. For those who aren’t in one of the early groups to be vaccinated, there is plenty of time to schedule a mammogram. So, it’s ideal to get one before the vaccine. But vaccines are important, so if you can’t schedule a screening mammogram before a vaccine becomes available to you, waiting a four to six week after the second dose would most likely not cause any harm, Dr. Morris said.

She emphasized that these recommendations are only for screening mammograms. Anyone who has a lump in their breast or a new symptom should schedule a mammogram as soon as possible regardless of vaccine status. The technologists who perform the mammograms ask every patient if they’ve recently had a vaccine and makes a note of that information for the radiologists so they are aware of that status. If something shows up on the mammogram, the patient would still need to come back in for a follow-up work-up, but Dr. Morris said she would reassure the patient that it could just be a reaction to the vaccine.

For those who are currently in treatment for breast cancer, or those who have been cured, she recommends getting the vaccine in the arm nearest the breast that was not related to the breast cancer.