New guidelines issued by the Society of Breast Imaging suggest that women should pay attention to the timing of their mammograms in relation to when they receive COVID-19 vaccinations.  Why is that?

A potential sign of having breast cancer is axillary adenopathy, or swelling of the lymph nodes in the armpit.  When a radiologist finds an enlarged lymph node on a mammogram, that’s a sign of concern and the patient will require additional studies.   As someone who does a lot of breast reconstruction for women with breast cancer, I see women almost every day who were called back for additional testing when a mammogram showed something abnormal.  It creates a lot of anxiety.

Having swollen axillary nodes does not mean that a person has breast cancer.  It does mean that more studies are needed to determine the cause.  While rare, axillary adenopathy can happen after receiving influenza, human papilloma virus (HPV), and TB vaccinations.  It happens more frequently, however, after receiving COVID-19 vaccine injections.

During the COVID-19 vaccine trials, 11% of people who received the Moderna vaccine developed swelling in their axillary lymph nodes after one dose.  That increased to 16% after the second dose.  Swelling of armpit lymph nodes was also seen in the Pfizer trial, but the numbers were lower (64 cases in the vaccine group vs 8 cases in the placebo group, out of thousands in the study).  Typically the swollen nodes occur in the armpit of the arm where the vaccine was administered, and the swelling lasts from 1 to 10 days.

Because of this concern about axillary lymph nodes, the Society of Breast Imaging makes this recommendation:  “If possible, and when it does not unduly delay care, consider scheduling screening exams prior to the first dose of a COVID-19 vaccination or 4-6 weeks following the second dose of a COVID-19 vaccination.”

Keep in mind that this discussion relates to routine screening mammograms  only.  If you have symptoms related to a breast, like pain, skin changes, nipple discharge, or a palpable lump, imaging should NOT be delayed. Get that evaluated right away. Don’t make decisions based on when you might receive a COVID-19 vaccination.