This is not a blog that addresses safety and effectiveness of the COVID-19 vaccine nor is it a blog that addresses when and if your patient should get a screening mammogram. What it is about is how the COVID-19 vaccine can temporarily affect lymph nodes that then can give a false result on the mammogram.
Firstly, there is no connection between the COVID-19 vaccine and breast cancer. But what radiologists are seeing is that in some women, the vaccine can cause a temporary enlargement of some lymph nodes that can then result in a “false positive” mammogram.
The COVID-19 vaccine is similar to other vaccinations in this regard. Lymph nodes under the axilla, near where a person has gotten a vaccine can become enlarged as part of the normal immune response to the vaccine. Sometimes this has previously been seen with the shingles vaccines, pneumonia vaccine the diphtheria/tetanus/pertussis vaccines, or even the flu vaccine. There also might be a more prominent lymph node immune response if one were to have a flu shot at or near the time as an additional COVID-19 vaccine. The COVID-19 vaccine causes a more intense immune response than most other vaccines, but in fact, we want that to happen in order to offer the most protection. For two-part vaccines, the larger lymph node response can appear after either the first or second shot. This lymph node response, if it should happen, will return to normal size in a few weeks.
If the mammogram shows lymph node enlargement and there’s not an obvious explanation for the change, the radiologist is likely to consider this an abnormal finding. That will mean a call back mammogram for possibly additional views, but also an ultrasound of the nodes. Once the lymph nodes are then measured, there will then likely be another f/u ultrasound in 3 months to assure a return to normal size. There may also selectively be biopsies of the lymph nodes. This chain events adds to costs and to anxiety.
Radiologists at mammogram centers are now routinely recommending waiting 4-6 weeks after the COVID-19 vaccine (and now likely all vaccines), before the screening mammogram. In my area, patients are asked questions about if and when they had their COVID-19 vaccine and scheduling 6 weeks out. The other option of course is for women that are getting screening mammograms, they get that prior to their vaccine.
However, if the mammogram is a diagnostic mammogram, it is recommended not to delay that. If they have onset of lymph node enlargement/breast region pain after the COVID-19 vaccine, that should be evaluated and recommendations for appropriate follow-up should be made.
Just to reiterate though, patients should know that there is no danger of breast cancer associated with the COVID-19 vaccine. And patients should be reassured that temporary enlargement of the lymph nodes after the vaccine means the immune system is responding appropriately.
Resource: National Comprehensive Cancer Network. https://www.nccn.org
