It's a bit of a Catch-22: COVID vaccinations are making it possible for more women to venture out and get mammograms after putting them off for a year or so. But those same vaccinations appear to be distorting results and leading to false positives on the exams, reports the Los Angeles Times. The reason, as laid out in the Times and in a post at Johns Hopkins Medicine, is fairly straightforward. The COVID shots trigger a response in the immune system, and that sometimes results in enlarged lymph nodes. If these show up on a mammogram, that raises a red flag and typically results in the women being called back for further tests. The enlargement would be temporary if caused by a vaccination, so a doctor might ask a woman to come back in a few weeks for a new exam.
All of which means that women and their doctors need to weigh the risk of holding off on a mammogram even longer to avoid the stress of a possible false alarm. "It's a bit of a balancing act," Dr. Lisa Mullen of Johns Hopkins tells the Times. It's not clear how many women have been affected, but at least anecdotally doctors are seeing a spike in mammograms with enlarged lymph nodes. In her post at Johns Hopkins, Mullen suggests that women who already have had their shots wait four to six weeks after the last one before scheduling a mammogram. But if they're experiencing breast pain, detect a lump, or have any other abnormalities, they should get a mammogram without delay. "It's better to be safe than sorry," reads the post. (Generally, cancer diagnoses have increased of late because people delayed screenings during the pandemic.)