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COVID-19 Vaccines Can Cause Lumps That Mimic Breast Cancer

CU Cancer Center member Anosheh Afghahi, MD, explains what’s going on and how doctors are dealing with the problem.

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Written by Greg Glasgow on June 3, 2021

The COVID-19 vaccines are beginning to significantly slow the spread of the virus, but the Pfizer and Moderna and vaccines are having an unforeseen consequence for breast cancer doctors. The vaccines often cause swelling in the armpit or underarm that can mimic the lumps associated with breast cancer, causing some women undue concern.

Medical oncologist and University of Colorado Cancer Center member Anosheh Afghahi, MD, has encountered the problem in her own practice; in the following discussion she explains what is happening and what providers are doing about it.

What is the issue breast cancer doctors are encountering in regard to the COVID-19 vaccine?

After getting a COVID-19 vaccine, we sometimes see swelling of the lymph nodes in the underarm area on the same side of the body where you received the shot. This is your body’s immune system response, but it can also cause problems because when these lymph nodes swell only on one side of the body and they’re seen on a mammogram, it can create the need for more imaging, follow-up imaging, or a biopsy. It can definitely be a cause of anxiety or stress.

Are you issuing any recommendations regarding mammogram timing as it relates to getting a vaccine?

To lessen the need for more testing, the Society of Breast Imaging has set up some guidelines to help the patient and the providers. One option is for patients to have their screening mammogram before they have their first dose of the COVID-19 vaccine so they can reduce the chances of this happening. If they have already received the COVID-19 vaccine, the recommendation is to finish that and get the screening mammogram four to six weeks afterward. When you get a mammogram, we now routinely ask if you have had a vaccine in the last three months, and we also ask on which side you received it. We put that in the notes for the mammogram report so the doctors have a higher suspicion that this is probably not anything concerning, but rather is secondary to the vaccine.

Are the recommendations any different for someone with a history of breast cancer?

If someone has a history of breast cancer and they’ve had a COVID-19 vaccine and they feel a lump in the underarm on the same side as the shot, certainly it’s OK to wait for a week or two at the most to see if that swelling goes down. But if it doesn’t go down, then, given their history, it’s better to just reach out to the provider and make sure that the imaging the provider recommends is being done. It has increased follow-up imaging a bit for our patients, because if they have a history of breast cancer, we don’t want to just assume that it’s the vaccine. A lot of times if the radiologist sees that, they will say, “Let’s just get a repeat ultrasound six to 12 weeks later, just to confirm that this swelling has improved.”

Does the vaccine cause lumps in the breast as well, or only in the underarms?

In terms of lumps inside of the breast, that is not really something that we have seen as often with the COVID vaccine. These are really lumps that are in the lymph nodes in the armpits or underarms. If you have a new breast mass, then you should definitely reach out to your provider. Sometimes it’s a little difficult because there is some auxiliary breast tissue that goes high up, so unless you have an ultrasound or a mammogram you can’t always distinguish between breast tissue and a lymph node. In general, if something is not getting smaller and softer within the span of a week, or if it’s getting larger or there are other associated symptoms, like a rash, anything that makes it more suspicious, then it’s always better to just reach out and have the provider do a clinical breast exam and order an ultrasound.

Topics: Breast Cancer