Physicians Seeing Increased Cancer False Positives Due to Vaccine Side-Effect March 2, 2021

Written by MSDC Staff

People receiving a COVID vaccine are showing enlarged lymph nodes, which may be mistaken for cancerous growth when it is nothing more than a temporary side effect.

A study published in the American Journal of Roentgenology notes that patients with auxiliary adenopathy identified on breast imaging after receiving a COVID vaccine are increasing. This phenomenon has been noted on social media by MSDC member Anjali Malik and others. While swelling is a normal side effect after being vaccinated in general, mammograms and chest scans can show white blobs that are easily confused for cancer. 

According to the New York Times, enlarged lymph nodes are not listed as a side effect in FDA documentation for the Johnson & Johnson vaccine. The Moderna study showed 11.6% of patients reported swollen lymph nodes. The Pfizer had a low reported incidence but the Times notes radiologists believes incidents are higher than reported.

The Society of Breast Imaging makes a series of recommendations for helping patients navigate this situation including:

  • Physician offices should document patients' vaccine information on an intake form.
  • Offices should consider including a warning statement on forms about the impact of the COVID vaccine on the scan.
  • Physicians should consider scheduling a second scan 4-12 weeks post-visit.

For patients undergoing cancer treatment in one breast, the CDC recommends receiving the vaccine in the opposite arm or thigh to minimize false diagnosis.