Swelling after COVID-19 injections can cause false alarms for cancer

Getting a mammogram or other cancer check soon after a COVID-19 vaccination? Be sure to let the doctor know about the injection to avoid a false alarm about a temporary side effect.

This is the advice of cancer experts and radiologists. Sometimes the lymph nodes, especially in the armpit, swell after vaccinations. This is a normal reaction of the immune system, but could be mistaken for cancer if it shows up on a mammogram or other scan.

“We need to get the word out,” said Dr Melissa Chen, radiologist at the MD Anderson Cancer Center in Houston, who recently had to reassure a frightened patient who was seeking cancer screening due to enlarged lymph nodes.

A group of experts from three cancer centers – MD Anderson, Memorial Sloan Kettering of New York and Dana-Farber of Boston – last week published recommendations in the journal Radiology on how to handle complicated scans by the effect. secondary.

The main message: “This should not prevent patients from getting vaccinated,” said Chen, one of the co-authors.

Lymph nodes are part of the immune system where anti-infective white blood cells collect, spots usually too small to be felt. But they can swell during illness and after other types of vaccines. And with the planned increase in COVID-19 vaccinations, doctors should “prepare to see large volumes” of imaging tests – including chest CT scans, PET scans, and mammograms – that show swollen lymph nodes, according to similar recommendations in the Journal of the American College of Radiology this week.

The most commonly affected nodes are in the armpit and near the collarbone, on the same side as the vaccination, Chen said.

The Food and Drug Administration lists the swelling along with other injection-related reactions commonly reported in studies of the Pfizer and Moderna vaccines, but not the Johnson & Johnson vaccine.

It is not known how often this happens. The FDA found that 16% of Moderna study participants reported underarm swelling after their second dose. But if the lymph nodes are only slightly enlarged, they may show up on a medical scan without people noticing any lumps.

Consumer advice is always evolving. Where the experts agree: if you have been vaccinated recently, let the radiologist know before any analysis. This will help them assess whether an enlarged lymph node is likely vaccine-related and can simply be watched, or if it is worrying enough for a biopsy or other test.

And try to schedule an upcoming screening or other cancer-related test before vaccination if possible without losing your place in the vaccination line, the radiology committee said.

People with active cancer on one side of the body may choose vaccination on the opposite side to minimize confusion.

Do not delay urgent examinations, stress radiologists. But there is some disagreement over elective testing. The radiology committee said it plans to schedule purely routine screenings six weeks after vaccination. In contrast, the Massachusetts General Hospital guidelines recommend managing the side effect through good communication rather than delayed screening.

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