Red flags leading to audibles in mammograms
Doctors fear COVID-19 vaccines messing with results of breast cancer screenings
After more than a year of anxious waiting, women newly vaccinated against COVID-19 are flocking back to mammography clinics to catch up on routine tests that were delayed by the pandemic. In some cases, they’re met with one more pandemic surprise: a false red flag for breast cancer.
Like a sore arm or slight fever, lymph nodes enlarged by the immune system’s response to a COVID-19 vaccine are virtually always a sign that the vaccine is doing its job.
But to the medical specialists who scour mammograms for signs of malignancy, the unexplained appearance of swollen lymph nodes has typically sparked concern and a recommendation that the patient be called back for further testing.
The result has been new uncertainties for women and the doctors who care for them.
If it’s a false alarm, women certainly don’t need the worry-inducing call reporting an “abnormal reading” on their mammogram. And few welcome the additional tests that tend to follow.
But as much as doctors wish to spare their patients unnecessary angst, they also want to avoid missing a signal that could be important.
“It’s a bit of a balancing act,” said Dr. Lisa Mullen, a breast imaging specialist at Johns Hopkins University School of Medicine in Baltimore. With many basic questions about the rash of enlarged lymph nodes still unanswered, the world of breast cancer screening has been forced to call some audibles.
The radiologists who scour mammograms for signs of cancer are not easily rattled. They examine thousands of breast images each week and make lots of judgment calls.
It’s not very often they are downright flummoxed.
On a typical prepandemic day, Dr. Hannah Milch at UCLA Medical Center might have seen one screening mammogram ambiguous enough to recommend further testing. And those cases rarely involved swollen lymph nodes in a woman without a notable risk for breast cancer.
In fact, radiologists say those “axillary” lymph nodes are usually elusive. Studies have shown that no more than 0.04% of mammograms reveal enlarged lymph nodes in women with no other sign of illness or malignancy. Tucked into the armpit, they are more likely to recede from a mammogram image than to photobomb it.
But after COVID-19 vaccines began to roll out, and health care workers and older women (the ones at greatest risk of breast cancer) began to pour in for mammograms, Milch started recommending callbacks five to seven times per day. In most cases, they were for “adenopathy” — lymph nodes that seemed unusually enlarged.
Milch’s colleagues reading mammograms across the country were seeing the same thing.
“I thought, ‘What is going on here?’ ” she said. “It definitely stimulated conversation.”
The body’s lymphatic system plays a key role in collecting and removing cellular debris from the body. When the body is fighting an infection — or thinks it is, after a dose of vaccine — the immune system dispatches an army of cells and proteins to mount a defense, leaving a lot of detritus in its wake.
Cancer, too, mobilizes a lot of cellular machinery. It uses the lymphatic system to travel to distant sites and leaves behind a telltale mess.
Close to both the breast and whichever arm gets a jab of vaccine, the 10 to 20 lymph nodes inside each armpit can act as a sentinel when radiologists see signs that they are swollen. But whether a node is enlarged due to infection, vaccine, trauma or cancer is not always clear.
To gain clarity on that life-or-death question, a woman is usually called back for an ultrasound or a biopsy, in which tissue is removed from the breast for further testing.
Radiologists have long known that a recent dose of vaccine for shingles, tetanus or flu can cause lymph nodes to appear slightly swollen. But the sudden appearance of so many swollen lymph nodes, in so many women, came as a shock. In many cases, so was the size of the swelling.
“They seemed to be more prominent,” said Dr. Constance Lehman, chief of breast imaging at Massachusetts General Hospital in Boston. “We had seen mildly enlarged nodes with prior vaccinations but not to this degree.”
By late February, articles in specialty journals began to detail what radiologists were seeing. And by midspring, expert panels had been convened by the Radiological Society of North America and the Society of Breast Imaging.
Women should be asked if they’ve been vaccinated against COVID-19, how recently and in which arm they got their jab, the experts advised. If possible, women should plan a screening mammogram at least six weeks following her second dose of vaccine. Women who have had a previous breast cancer should get their shot in the opposite arm.
And in the absence of other evidence pointing to the possibility of cancer, recently vaccinated women with enlarged axillary lymph nodes should be called back at least six weeks later to give the lymph nodes time to recover.
While the members of both expert panels acted quickly to issue their recommendations, they acknowledged that the advice amounted to “expert opinion without data,” said Milch, who was among the authors of the Society of Breast Imaging recommendations.
The new guidance was largely based on anecdotal evidence generated in response to the PfizerBioNTech and Moderna vaccines. It’s not clear yet whether Johnson &
Johnson’s single-dose vaccine will evoke the same response.
Nor is it clear how long it will take for the swelling in some women’s lymph nodes to abate or whether their reactions will be more pronounced after the second shot than after a first. Radiologists also wonder whether some configurations of swollen lymph nodes can be dismissed lightly, while others warn of something more ominous.
But one message is clear: If a woman has felt a lump in her breast or is experiencing soreness in or around her breast or discharge from her nipple, she should get her symptoms assessed right away.
However, radiologists are quick to point out that the enlarged nodes they are seeing do not amount to a link between the vaccine and breast cancer.
“I see no connection whatsoever,” Lehman said.