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COVID-19 vaccination and Cancer


Physicians at MD Anderson are seeing an uptick in mammograms and other diagnostic imaging exams showing potential findings that can be confused with cancer in patients who’ve recently received one of the mRNA COVID-19 vaccines from Pfizer-BioNTech and Moderna.

Johnson & Johnson’s adenovirus-based vaccine has only begun to be distributed, and people may or may not also see a similar response from this vaccine.

Some people who receive a COVID-19 vaccine may experience swollen lymph nodes on the same side of the body where they received the injection. Dr. Leung notes that lymph node enlargement is a normal reaction to the COVID-19 vaccines, as well as other vaccines, such as those for influenza and HPV. In clinical trials for the Moderna vaccine, approximately 16% of patients between the ages of 18 and 64 and 8.4% of patients over 65 developed swollen lymph nodes within 2 to 4 days after either dose of the COVID-19 vaccine, according to the Centers for Disease Control and Prevention.

If you haven’t scheduled your screening or vaccine appointment, Leung recommends getting your breast cancer screening before you receive the COVID-19 vaccine.

If you’ve already been vaccinated, schedule your diagnostic imaging exam 6 to 10 weeks after your second COVID-19 vaccine dose. In some cases, you shouldn't delay your screening or COVID-19 vaccination.

If swollen lymph nodes appear, doctors will keep an eye on the swelling to make sure it’s benign.

Cancer survivors should ask to have the vaccine administered in the arm opposite of where the cancer is or was, if possible. For women who have cancer in both breasts, talk to your doctor to see which arm would be medically appropriate.

This will help support your immune response and reduce the chances that swollen lymph nodes caused by vaccination show up on your mammogram. Enlarged lymph nodes can falsely affect cancer screening and diagnostic imaging results up to 6 weeks after vaccination.

Cancer doesn’t stop for COVID-19, so it’s important not to put off your cancer screenings – or the opportunity get a COVID-19 vaccine. “Whether you currently have cancer or not, it’s important to continue your regular screenings so your doctor can catch any potential issues as early as possible, increasing your chances of successful treatment,” says Leung.

And, she adds, vaccination is vital for slowing the spread of COVID-19 and ultimately achieving herd immunity. Cancer patients are at increased risk for developing severe complications from COVID-19, and MD Anderson experts have determined that the COVID-19 vaccines are safe and recommended for former and cancer patients.