Impaired primary, but not secondary, immune response in breast cancer patients under adjuvant chemotherapy.

The antibody response after vaccination against tick-borne encephalitis (TBE) was studied in patients with breast cancer. Although sex- and age-matched control persons produced high titers of anti-TBE antibodies 2 to 4 weeks after the second of two consecutive vaccinations, patients with breast cancer who were first vaccinated after the start of adjuvant chemotherapy consisting of cyclophosphamide, methotrexate and 5-fluorouracil (CMF) failed to do so. The lack of anti-TBE antibody production was found not only in patients under CMF chemotherapy, but also in those primarily vaccinated 6 to 12 months after the termination of CMF treatment. Patients with breast cancer who had been vaccinated either before or after the onset of disease, but before the initiation of chemotherapy, were shown to have developed significant anti-TBE antibody titers which persisted throughout the course of adjuvant treatment and could be boostered by revaccination during the course of CMF administration. The authors conclude that patients with breast cancer undergoing adjuvant chemotherapy experience a serious and prolonged defect in primary antibody production, whereas secondary immune responses remain unimpaired.