Can the flu shot be administered to patients undergoing radiotherapy for breast cancer?

Influenza Vaccination for Breast Cancer Patients on Radiotherapy

Influenza vaccination is safe and recommended for breast cancer patients undergoing radiotherapy, as it provides essential protection against influenza infection in this high-risk population. 1

Safety and Efficacy

• Influenza vaccination is particularly important for cancer patients, including those on radiotherapy for breast cancer, as they face significant morbidity and mortality risks from influenza infections 1
• The trivalent inactivated influenza vaccine is safe and well-tolerated in breast cancer patients, though immune response may be somewhat reduced compared to healthy individuals 2, 3
• Cancer patients should receive the inactivated vaccine rather than live attenuated influenza vaccine (LAIV) due to their potentially compromised immune systems 1, 2

Timing Considerations

• For breast cancer patients on radiotherapy, there are no specific contraindications to receiving the flu shot during treatment 1
• Optimal timing for vaccination is not clearly defined for radiotherapy specifically, but general guidance suggests administering the vaccine mid-cycle of treatment or at the furthest possible time point away from treatment during a given cycle 1, 2
• For patients with solid tumors, vaccination should ideally be given mid-cycle, preferably 2 weeks after chemotherapy and/or before administration of the subsequent cycle 2

Immune Response Factors

• Cancer patients may experience disease- or treatment-related immunosuppression, potentially resulting in a suboptimal serologic response to influenza vaccination 1
• Despite potentially reduced response, a considerable number of cancer patients still reach protective antibody levels after vaccination 2, 3
• Studies show that breast cancer patients, including those undergoing treatment, can develop a serological response to influenza vaccine, with response rates ranging from 44.4% to 88.9% in some studies 4
• The number of chemotherapy cycles does not necessarily have a negative effect on the breadth of antibody response to influenza vaccination 5

Strategies to Improve Protection

• Some data suggest increased seroprotection rates with vaccines containing adjuvants or higher doses of antigen 2
• Two doses of adjuvanted vaccine may be required in some cancer patients to achieve similar seroprotection rates to those achieved in healthy controls with one dose 2
• Vaccination of household contacts and healthcare personnel is highly recommended to increase herd immunity in the patient's environment 1

Common Pitfalls to Avoid

• Do not withhold vaccination due to concerns about reduced efficacy, as even a suboptimal response provides some protection 1
• Do not administer live attenuated influenza vaccines to cancer patients due to their potentially compromised immune systems 1, 2
• Do not assume that patients receiving rituximab will have adequate response to vaccination, as they may have impaired immune response associated with persistent memory B-cell depletion 2

Special Considerations

• Patients with a history of prior influenza vaccination may have higher pre-vaccination antibody titers, comparable to healthy individuals 5
• The Italian Society of Medical Oncology (AIOM) recommends annual influenza vaccination for all cancer patients, regardless of the specific anti-neoplastic treatment they are receiving 1, 3