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This COVID-19 Vaccine Side Effect Could Be Confused With A Breast Cancer Symptom, Says Study

With the widespread rollout of the COVID-19 vaccine, vaccine-induced adenopathy or swollen lymph node near the armpit or the collarbone has been seen in people, mistaking the symptom as a sign of cancer, or particularly a breast cancer sign.

The swelling occurred on the same side of the arm where the shot was given to people who were immunised recently. On breast imaging tests such as chest scans or mammograms, the images may indicate the spread of cancer or tumour in the breast area.

This has created a panic among the patients; however, medical experts have advised people to not be alarmed by this side effect as it could be a common immune system response after the vaccination.

Let's know about this condition in details.

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What Is Adenopathy?

Adenopathy or lymphadenopathy is characterised as swollen lymph nodes. It is a common abnormal symptom during the physical examination, used to detect an infection, inflammatory conditions or neoplasm. [1]

The swelling is identified as:

  • bean or pea-sized lumps under the skin area,
  • redness over the swollen nodes,
  • feeling of warmth when touched, and
  • tendered lumps.

Why The Lymph Nodes Swell After The Vaccination?

Lymph nodes are a part of the lymphatic system that assist in immunity by filtering and draining the fluid within the lymphatic duct and by recycling cells that are at the end of their life cycle.

There are around 800 lymph nodes commonly found in the armpit, abdomen, neck, groin and thorax. [2]

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The lymph nodes contain a fluid-like substance called lymphocytes (white blood cells). When pathogens enter the body, the lymph nodes are the first to suffer. They trap all kinds of antigens such as bacteria and viruses within their fluid and as a result, swell up. [3]

As the vaccines contain live pathogens, the lymph nodes closest to the vaccine shot side may get enlarged as they start producing antibodies as a result of an immune system response.

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Some experts suggest that swollen lymph is a normal response to all kinds of vaccine and it is in fact, a good sign that the body is responding well to the vaccine. However, one must keep an eye on the number of days for which the swelling is present.

If the swelling is present near the armpit or breast area (as the vaccine is given in an arm) and does not go away within a few days or weeks, one must consult a medical expert soon, as it could be a sign of breast cancer.

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COVID-19 Vaccine And Swollen Lymph, Case Studies

As per the case reports published in the journal Elsevier Public Health Emergency Collection, out of the four women who were diagnosed with swollen lymph nodes after the COVID-19 vaccination, two have a family history of breast cancer while the other two do not. [2]

Case 1: A 59-year-old woman was diagnosed with a palpable lump near her left armpit, nine days after the first dose of Pfizer-BioNTech, a COVID-19 vaccine. Sonography and mammogram were carried out. She has a family history of breast cancer. Her sister was diagnosed with breast cancer at the age of 53.

Case 2: A 42-year-old woman was diagnosed with multiple lymph nodes on the left side of the armpit, five days after the second dose of the Pfizer-BioNTech. Routine screening mammography and breast ultrasound were carried out. She has a family history of breast cancer. Her paternal grandmother was diagnosed with breast cancer at the age of 80.

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Case 3: A 42-year-old woman was diagnosed with benign bilateral masses near the left upper breast area, 13 days after the first dose of the Moderna, a COVID-19 vaccine. Sonography was carried out. In her family, no family history of breast cancer was reported.

Case 4: A 57-year-old woman was diagnosed with a single lymph node on the left side of the armpit, eight days after the first dose of the Pfizer-BioNTech. Routine screening mammography and breast ultrasound were carried out. She has no family history of breast cancer.


Preventive Measures

  • One must not delay routine mammograms in case they have some breast-related conditions, regardless of they have taken the COVID-19 vaccine or not.
  • If the inflammation near the vaccination area stays for a significant amount of time, gets harder and bigger followed by other symptoms such as running nose or pain in the breast, there can be a risk of breast cancer. In this case, seek urgent medical advice.
  • Schedule a mammogram weeks before getting the COVID-19 vaccine.
  • If you have already received the first dose of the vaccine, wait for 4-6 weeks after the second dose.
  • Do not cancel either of the two i.e. mammogram appointment or vaccination just because of one.
  • If you have a breast screening going on, inform your doctor about your vaccination schedule and the arm used for vaccination.
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    To Conclude

    Both breast cancer routine checkups and vaccination are important. One must not worry about the swollen lymph nodes as it is a normal vaccination symptom. However, if you are undergoing routine checkups for breast cancer or any breast problems, it is advisable to keep the doctor in the loop about the COVID-19 vaccination, so that they can efficiently monitor any change or side effects.

    The other most important point is, swollen lymph nodes are observed mainly after Pfizer and Moderna vaccine shots. In India, Covaxin and Covishield are used for vaccination.