Background:Our aim was to evaluate the serological response and safety of influenza vaccine in patients with breast cancer in Mexico.

Material/Methods: Between October and December 2001, patients with breast cancer were vaccinated with a split virus vaccine. Hemagglutination inhibition assay titers were measured before vaccination and 4–6 weeks later. Titer ratios were used as the primary measure of response. When comparing rate of response according to treatment, stage, or other patient-related variables, individuals with post vaccination titers ≥1:40 for all 3 antigen strains were called respondents.

Results: We analyzed 146 patients who were vaccinated and had influenza antibodies measured before and after vaccination. Seventy-two (49.3%) had locally advanced breast cancer, 117 (80.1%) were receiving cancer treatment, 91 (62.3%) were on chemotherapy. Response to vaccine was 47.2%; we found an additional 25.3% of patients who responded to two of the serotypes. In patients receiving chemotherapy the response rate was lower (p=NS).

Conclusions:The results of the present study show that influenza vaccine is safe and well tolerated in patients with breast cancer, but we observed a lessening of the immune response among patients receiving chemotherapy. Influenza vaccination should be recommended in all patients with breast cancer, regardless of the anti-neoplasic treatment.

Keywords: Breast Neoplasms - immunology, Antibodies, Viral - immunology, Influenza A virus - immunology, Influenza B virus - immunology, Influenza Vaccines - immunology, Influenza, Human - prevention & control, Vaccination - adverse effects