Mansoor Raza Mirza, MD from Region Hovedstaden discusses an abstract from ASCO 2020 entitled Final survival analysis of Smita Bhatia, MD of UAB discusses an article in the Journal of Clinical Oncology entitled Total Body Irradiation and Risk of Breast Cancer After Blood or Marrow Transplantation: A Blood or Marrow Transplantation Survivor Study Report
Intent
To explore the link between total body irradiation (TBI) and subsequent breast cancer in women treated for hematologic malignancies through blood or marrow transplantation (BMT).
PATIENTS AND MAINS
Participants were drawn from a retrospective cohort study, the BMT Survivor Study (BMTSS), which included patients who underwent transplantation between 1974 and 2014 and survived after BMT for around 2 years. Patients with pre-BMT chest radiation or breast cancer records were ruled out. Participants completed the BMTSS survey which included information concerning the diagnosis of breast cancer. Subsequent breast cancer has been verified by examination of pathology reports or doctor’s notes. The correlation between TBI and subsequent breast cancer was tested by the Cox proportional hazards models. Compared to that of the general population, standardized incidence ratios were determined to assess the excess risk of subsequent breast cancer.
OUTCOMES
A total of 1,464 female BMT (allogeneic: n = 788; autologous: n = 676) survivors were included, with a median follow-up of 9.3 years after BMT. In 660 patients, TBI was used (46 percent). Thirty-seven women (allogeneic: n = 19; autologous: n = 18) developed subsequent breast cancer. Multivariate analysis found that TBI exposure was correlated with an increased risk of breast cancer among survivors of allogeneic BMT (hazard ratio [HR], 3.7 [95 % CI, 1.2 to 11.8]; P = .03) and autologous BMT (HR, 2.6 [95 % CI, 1.0 to 6.8]; P = .048). An increased risk of subsequent breast cancer among autologous BMT survivors was associated with pre-BMT exposure to alkylating agents (HR, 3.3 [95 percent CI, 1.0 to 9.0]; P = .05). Compared to that in the general population, TBI exposure in allogeneic BMT survivors was associated with a 4.4-fold higher risk of subsequent breast cancer and a 4.6-fold higher risk in autologous BMT survivors.
Summary
Breast cancer screening for early detection should be informed by the relationship between TBI and subsequent breast cancer, especially among those exposed at a young age, and by pre-BMT exposure to alkylating agents.