Chemotherapy for breast cancer negatively affects the immune system, such that survivors may lack sufficient antibodies to protect against common illnesses. Chemotherapy reduces the body’s immune responses and is associated with long-term changes immune parameters, according to a study published in Breast Cancer Research.1 This suggests that survivors could benefit from additional post-treatment monitoring.
About a third of breast cancer patients receive chemotherapy, which is effective and increases survivorship. This study investigated the long-term impact of chemotherapy on immunity.
The research team, from the University of Leeds and Leeds Teaching Hospitals NHS Trust in the United Kingdom, measured levels of lymphocytes. Chemotherapy was found to reduce some types of lymphocytes for at least 9 months after treatment. Even when patients had routine vaccinations for such infections year ago, they may be vulnerable to some infections because of these effects on their immune system.
This observational, longitudinal study investigated the immune system of 88 women with breast cancer at interval from 2 weeks to 9 months after completing chemotherapy. The researchers did not have pre-chemotherapy data for 26 of these women.
All major types of lymphocytes had significantly lower levels after chemotherapy, including T cells, B cells, and natural killer cells. Most lymphocytes recovered by 9 months, but the effects were long-term for B cells and helped T cells. B cells ultimately produce antibodies, and helper T cells help antibody production. Both B and helper T cells only recovered to about 65% of their initial levels in the first 6 months and did not further recover in the next 3 months. Tetanus and pneumococcus antibody levels were reduced and remained low after 9 months.
“We were surprised that the impact of chemotherapy is so long lived,” said Thomas Hughes, DPhil, from the School of Medicine at the University of Leeds. “We were also surprised that smoking and choice of chemotherapy agent influenced the dynamics of the recovery of the immune system. We might need to take into account the future immune health of patients with breast cancer when planning treatments, but more research is needed to determine whether this would improve patient outcomes.”
1. Verma R, Foster RE, Horgan K, et al. Lymphocyte depletion and repopulation after chemotherapy for primary breast cancer. Breast Cancer Res. 2016;18(1):10.