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Experts say breast cancer screenings can be delayed after getting a COVID-19 vaccination, but diagnostic mammograms should not be postponed. Aleksandar Nakic/Getty Images
  • Researchers say swollen lymph nodes caused by COVID-19 vaccination can produce “false positives” in breast cancer mammograms.
  • Some medical facilities are delaying breast cancer screenings for 4 to 6 weeks after getting the vaccination.
  • However, experts say a diagnostic exam being done after breast cancer symptoms are discovered should not be postponed.

All data and statistics are based on publicly available data at the time of publication. Some information may be out of date.

One potential side effect of the COVID-19 vaccine is swollen lymph nodes.

It’s normal and it’s temporary, but it can lead to unclear mammogram results.

Articles published in the journals Clinical Imaging and Radiology detail several cases of unclear mammogram readings following COVID-19 vaccinations.

In some of those cases, people underwent more imaging tests or biopsies.

The swollen lymph nodes occurred under the arm or near the collarbone on the same side of the body where the vaccine was administered.

“We have observed swollen lymph nodes in the armpit of many women following the COVID-19 vaccine,” said Dr. Emily Sonnenblick, a breast imaging radiologist at the Dubin Breast Center at Mount Sinai Hospital as well as an associate professor of radiology at the Icahn School of Medicine at Mount Sinai in New York.

“Lymph nodes are part of the body’s immune system. They swell as a normal response to a foreign substance, such as vaccine or infection,” she added.

Radiologists look for suspicious changes in the breast and armpit.

Enlarged lymph nodes can be a sign of cancer.

“But an isolated swollen lymph node in the absence of known breast cancer is a rare first sign of cancer,” Sonnenblick told Healthline.

Dr. Clayton Taylor is a breast radiologist with The Ohio State University Comprehensive Cancer Center – Arthur G. James Cancer Hospital and Richard J. Solove Research Institute.

Taylor told Healthline that it’s too soon to know how common swollen lymph nodes are after a COVID-19 vaccination. There’s also uncertainty how they might be seen on a screening mammogram and cause a false-positive result.

“However, from our experience since January of this year, the risk of a false-positive screening mammogram from a swollen lymph node associated with COVID-19 vaccination seems very small, as long as we collect information from our patients regarding COVID-19 vaccination status at the time of their appointment,” Taylor said.

“If a swollen lymph node from COVID-19 vaccination was identified on a screening mammogram and found to require further evaluation, we would ask the patient to return for a focused ultrasound evaluation of this area,” he added.

Dr. Deanna J. Attai is an associate clinical professor of surgery at the David Geffen School of Medicine at the University of California, Los Angeles.

Attai told Healthline it’s important to differentiate between screening mammography and diagnostic mammography.

Screening mammography is performed in people with no symptoms.

“The Society of Breast Imaging (SBI) has recommended that women wait approximately 4 to 6 weeks after the COVID vaccine to undergo screening mammography or to try to receive the vaccine prior to the mammogram,” Attai said.

Taylor said that screening mammograms can be safely and accurately interpreted in people who have recently received COVID-19 vaccination.

“As long as that vaccination information is gathered, as recommended by the SBI. Therefore, we are collecting COVID-19 vaccination information. But we are not recommending that women delay their screening mammograms at this time,” he continued.

“If a woman and her provider feel very concerned about the possibility of false-positive results from lymph node swelling, we suggest they schedule their screening mammogram 4 to 6 weeks after vaccination is complete. If in the future additional information becomes available, we will update our guidance about scheduling screening mammograms,” Taylor said.

Diagnostic mammograms should not be delayed.

If you have a new finding, such as a lump, abnormal discharge from the nipple, swelling of the breast, or any other change, get your mammogram, said Attai.

“Diagnostic studies are performed in women with a new finding, such as a lump, or who have an abnormal screening mammogram. These studies, per SBI, should still be performed. When at the facility, women should inform the mammography technologist about recent vaccination,” she said.

Sonnenblick explained that if you already have breast cancer, an enlarged lymph node can be a sign that it has spread.

If you notice any changes in your breast or underarm, such as pain or a lump, speak with your doctor.

Cancer screenings in general have slowed down during the COVID-19 pandemic, particularly for breast and colorectal cancer.

Shutdowns fueled part of the slowdown as well as fears of contracting the coronavirus.

Less screening resulted in fewer diagnoses.

After a steep decline in the spring and summer of 2020, cancer screening rates are picking up again. But there’s still a backlog of missed or delayed screenings.

A new prospective study of nearly 550,000 women found that skipping even one recommended mammography screening before a diagnosis of breast cancer significantly raises the risk of death.

Medical facilities across the country have taken steps to prevent COVID-19 transmission. These steps include spacing out appointments, physical distancing, mask wearing, and sanitizing procedures.

Talk with your doctor about COVID-19-related safety concerns and whether you should schedule a mammogram. Guidelines for screening mammograms vary according to individual risk factors.

“Patients who are symptomatic or may be contagious with COVID-19 should follow appropriate current public health recommendations,” Taylor said.

“However, having a personal history of COVID-19 infection would not be expected to interfere with screening mammograms,” he said.

“The most important thing is that women continue to undergo screening mammography and receive their COVID-19 vaccinations when they are available, since we know these are both proven to be very important for health maintenance,” Taylor said.