Published on February 24, 2021
COVID-19 Vaccine and Mammogram Results
The Society of Breast Imaging (SBI) has issued a three-page guidance recommending that women schedule their mammograms prior to their first dose of a COVID-19 vaccine, or four to six weeks following the second dose, because of a side effect that could be mistaken as breast cancer.
The guidance comes after patients who received a COVID-19 vaccine reported seeing swollen lymph nodes under their armpit, a natural immune response to the vaccine, triggering a false positive on a mammogram. The side effect has been seen with both the Moderna and Pfizer vaccines.
A series of case reports published online in the journal Clinical Imaging detailed four women who received the COVID-19 vaccine and then sought breast screening, including a 42-year-old woman who was found to have multiple swollen lymph nodes in her left armpit during a breast ultrasound. The woman had received her second dose of the Pfizer vaccine five days prior in her left arm. She had to return for a follow-up to rule out cancer.
The vaccine side effect “may cause some confusion when a woman has a mammogram,” said Dr. Patrick Francke, a radiation oncologist with the Carolina Regional Cancer Center in Myrtle Beach, S.C., in an interview with WPDE. “Are those lymph nodes enlarged because of the breast cancer or because of the recent vaccinations? Which may cause additional mammograms to be done or additional diagnostic procedures to be done whereas if we just timed that appropriately, accordingly before the vaccination or afterward we can avoid those extra procedures.”
How Common is Lymph Node Swelling as a Side Effect?
In clinical trials, 11.6% of patients who received the Moderna vaccine experienced swollen lymph nodes following the first dose, and 16% experienced it following the second dose. The swelling occurred in the arm and neck two to four days following vaccination with a duration of one to two days.
It was rarer in patients who received the Pfizer vaccine, but it was only reported as an unsolicited side effect (patients weren’t asked about it specifically), which means the “true incidence rate” is likely higher, according to the SBI guidelines. Swollen lymph nodes occurred in the arm and neck within two to four days of vaccination and lasted for about 10 days.
Still, it's very unusual to see enlarged lymph nodes in a normal routine mammogram – only 0.02%-0.04% of all routine mammograms do, according to the SBI.
"So, when we see it, it does raise a red flag, because when that kind of lymph node swelling is present, about 50% of the time, it can represent either a metastatic breast cancer, that has gone from the breast to the lymph node under the arm, or leukemia or lymphoma,” said Dr. Brett Parkinson, medical director of Intermountain Medical Center Breast Care Center in Murray, Utah, in an interview with HealthDay. "We do additional testing, usually ultrasound, and often we will do a biopsy to rule out one of those malignancies.”
How Do I Know It’s the Vaccine and Not Breast Cancer?
If you experience swollen lymph nodes following your vaccine and the symptom doesn’t go away within a week or is getting worse, call your healthcare provider.
If you believe it’s from the vaccine, and you are uncomfortable, try applying a warm, wet compress and taking an over-the-counter pain reliever (a recommendation from the Mayo Clinic).
Remember, the earmark of breast cancer is a mass or lump that forms in the breast tissue. Other signs include:
- Issues with the skin on your breast (excessive crusting or flaking, or redness and pitting, which the Mayo Clinic likens to the skin of an orange)
- Unusual changes to the overall size of your breast
- Changes to your nipple, such as crusting of the skin around the areola or if you notice your areola has recently become inverted
Changes in Mammogram Guidelines
According to a study published this week in the journal Radiology, women who skip even one scheduled mammogram before a breast cancer diagnosis face a significantly higher risk of dying from the disease.
“Regular participation in all scheduled screens (mammograms) confers the greatest reduction in your risk of dying from breast cancer,” said the study’s lead author, Stephen W. Duffy, professor of cancer screening at Queen Mary University of London.
Duffy and his team came to this conclusion after analyzing data from more than 500,000 women who were eligible for mammography screening between 1992 and 2016. They discovered that women who attended their annual mammograms in the two years prior to a breast cancer diagnosis had a 29% reduction in breast cancer mortality compared to women who missed a screening.
“While we suspected that regular participation would confer a reduction greater than that with irregular participation, I think it is fair to say that we were slightly surprised by the size of the effect,” Duffy said. “The findings support the hypothesis that regular attendance reduces the opportunity for the cancer to grow before it is detected.”
Whatever you do, get your mammogram, even if you have to delay it a month. Breast cancer does not take a break during pandemics and mammograms are effective at detecting breast cancer at earlier, more treatable stages.
If you have recently received a COVID-19 vaccine and have a screening coming up, the SBI guidelines recommend telling the clinician when and where (left vs. right arm) you received the vaccine. If the mammogram detects swollen lymph nodes, your doctor may recommend waiting a few weeks to see if it’s a vaccine side effect rather than suspecting cancer and sending you for an immediate biopsy.
If you have not yet received a COVID-19 vaccine, follow the SBI’s updated mammogram guidelines: schedule your screening prior to your first dose of the vaccine, or wait four to six weeks following the second dose.
Bottom line: You can — and should — get both the COVID-19 vaccine and your mammogram. Just spread them out and talk to your doctor if you have any questions.
- Unilateral axillary Adenopathy in the Setting of COVID-19 Vaccine
- Local Reactions, Systemic Reactions, Adverse Events, and Serious Adverse Events: Moderna COVID-19 Vaccine
- With 1 in 8 women to experience breast cancer, experts have new COVID-19 vaccine guidance
- COVID Vaccine Reaction Can Mimic Breast Cancer Symptoms
- Skipping Mammogram Increases Risk of Death from Breast Cancer
Recommended for You: