From the Guidelines
Breast cancer and reactive lymph nodes in response to vaccinations are related in that vaccinations can cause adenopathy, which may be indistinguishable from malignant nodal involvement.
Key Points
- Vaccination-associated adenopathy typically occurs in the axilla and supraclavicular region, which is a common site for metastasis in breast cancer patients 1.
- Lymph node enlargement following vaccination is related to locally activated antigens that accumulate at the injection site and later migrate to the draining nodes 1.
- Recognition of this association is crucial in patients with cancer, where it can lead to under- or overdiagnosis and under- or overtreatment, as well as heightened anxiety 1.
- COVID-19 vaccines, in particular, have been shown to cause regional adenopathy in up to a third of cases, which can be a diagnostic challenge in patients with breast cancer 1.
Clinical Implications
- It is essential to consider the patient's vaccination history when evaluating axillary or supraclavicular lymph nodes in breast cancer patients 1.
- Imaging findings related to regional and systemic immune response, such as increased nodal and splenic metabolic activity on 18FDG-PET, should be interpreted with caution in vaccinated patients 1.
From the Research
Relationship Between Breast Cancer and Reactive Lymph Nodes
The relationship between breast cancer and reactive lymph nodes in response to vaccinations is a topic of interest in recent studies.
- Reactive lymph nodes are commonly found in patients who have received COVID-19 vaccination, with an excess of 16% in patients who had received COVID-19 vaccination in the past 3 months 2.
- The presence of vaccine-induced hypermetabolic lymph nodes (v-HLNs) on 18F-FDG PET/CT after COVID-19 vaccination is associated with absolute lymphocyte count (ALC) and may be related to a stronger immune response to vaccination 3.
- Prior breast biopsy may negate the prognostic significance of sinus histiocytosis in breast cancer, suggesting that reactive changes in axillary lymph nodes may be influenced by previous biopsy 4.
Diagnostic Challenges
The presence of reactive axillary lymph nodes after COVID-19 vaccination can lead to diagnostic challenges in breast cancer patients.
- Metabolically active axillary lymphadenopathy is an adverse effect of COVID-19 vaccines, which may lead to unnecessary biopsy 5.
- Axillary lymph node characteristics on imaging modalities such as axillary ultrasound, breast MRI, and 18F-FDG PET/CT may differ between breast cancer patients and those with post-COVID-19 vaccination lymphadenopathy 6.
- Clinical information regarding injection site, vaccine type, and vaccination date is necessary to improve the interpretation and guide treatment towards the next steps of action 6.
Key Findings
Key findings from the studies include:
- Reactive lymph nodes are more common in patients who have received COVID-19 vaccination in the past 3 months 2.
- Absolute lymphocyte count (ALC) is associated with the presence of v-HLNs on 18F-FDG PET/CT after COVID-19 vaccination 3.
- Prior breast biopsy may influence reactive changes in axillary lymph nodes 4.
- COVID-19 vaccination can cause metabolically active axillary lymphadenopathy, leading to diagnostic challenges in breast cancer patients 5.
- Axillary lymph node characteristics on imaging modalities may differ between breast cancer patients and those with post-COVID-19 vaccination lymphadenopathy 6.