Can COVID-19 (Coronavirus Disease 2019) vaccines cause cancer?

COVID-19 Vaccines Do Not Cause Cancer

There is no scientific evidence that COVID-19 vaccines cause cancer. 1 The available guidelines and research strongly support the safety of COVID-19 vaccines in cancer patients, with no indication that these vaccines initiate or promote cancer development.

COVID-19 Vaccines and Cancer Patients: Safety and Efficacy

Safety Profile

• COVID-19 vaccines are generally well-tolerated in patients with cancer, with most adverse events being mild to moderate (grade 1 or 2), such as injection site pain, fatigue, myalgia, headache, and fever 1
• The most notable vaccine-related finding in cancer patients is transient axillary adenopathy (lymph node swelling), which can be mistaken for cancer progression on imaging but is a normal immune response 1
• Vaccination-associated adenopathy typically occurs in the axilla and supraclavicular region following deltoid muscle injection, which can create diagnostic challenges in patients with certain cancers 1

Benefits for Cancer Patients

• Cancer patients are particularly vulnerable to adverse outcomes from COVID-19 infections due to their underlying malignancy, treatments, comorbidities, and often advanced age 1
• Five non-randomized studies demonstrate that vaccinated cancer patients have significantly reduced risk of hospitalization and death from COVID-19 compared to unvaccinated cancer patients 1
• Vaccinated cancer patients were 56% less likely to experience hospitalization or death within 30 days of COVID-19 infection compared to unvaccinated cancer patients (odds ratio 0.44,95% CI 0.28-0.72) 1

Recommendations for Cancer Patients

Vaccination Timing

• When feasible, cancer patients should receive COVID-19 vaccines 2-4 weeks prior to initiating cancer treatment to optimize immune response 1
• For patients already on cytotoxic chemotherapy, vaccines can be administered between chemotherapy cycles 1
• For patients planning to start cytotoxic chemotherapy, the first vaccine dose should ideally be given at least two weeks before starting treatment 1
• Patients receiving lymphocyte or plasma cell-depleting regimens should delay vaccination for at least 3 months following the end of immunotherapy to achieve better antibody response 1

Imaging Considerations

• To avoid diagnostic confusion from vaccine-related adenopathy, routine cancer screening imaging should be scheduled either before vaccination or at least 6 weeks after the final vaccine dose 1
• Urgent imaging for acute symptoms, treatment monitoring, or complications should not be delayed due to vaccination 1
• The vaccine should be administered on the side contralateral to the primary or suspected cancer 1

Addressing Concerns About Cancer Risk

Lack of Evidence for Cancer Causation

• No major medical guidelines or authoritative bodies have identified COVID-19 vaccines as carcinogens 1
• Cancer patients are actually prioritized for COVID-19 vaccination due to their higher risk from COVID-19 infection 1
• The American Society of Clinical Oncology (ASCO) guidelines strongly recommend COVID-19 vaccination for cancer patients, which would not be the case if there were legitimate concerns about cancer causation 1

Importance of Documentation

• Vaccination information (dates administered, injection sites, laterality, and type of vaccine) should be documented in patient records and made available to interpreting radiologists to avoid misdiagnosis of vaccine-related adenopathy as malignancy 1

Special Considerations

Immune Response Variations

• Cancer patients may have lower seroconversion rates after vaccination, especially those with hematologic malignancies 1
• The efficacy of mRNA vaccines has been reported as 83% in patients with solid tumors and 72% in those with hematological malignancies 1
• Anti-CD20 or cytotoxic therapies may contribute to lower-than-expected immune responses to vaccines 1
• Despite potentially reduced antibody response, T-cell responses induced by vaccines remain strong enough to recommend immunization for most cancer patients 1

Potential Pitfalls

• Avoid misinterpreting vaccine-related adenopathy as cancer progression or recurrence by documenting vaccination status and timing 1
• Do not delay urgent cancer treatment for vaccination; the benefits of timely cancer treatment outweigh the potential for reduced vaccine efficacy 1
• Do not withhold vaccination from cancer patients due to unfounded concerns about cancer causation; the risk of severe COVID-19 is significantly higher than any theoretical risk from vaccination 1