title: The risk factors of toxicity during chemotherapy and radiotherapy in breast cancer patients according to the presence of BRCA gene mutation.
abstract: OBJECTIVE
  Treatment toxicity may decrease the treatment effectiveness due to the need to reduce the dose or increase the interval between cycles. The aim of this study was to distinguish the risk factors for treatment side effects in breast cancer patients and to assess the impact of BRCA1/2 mutations on the treatment toxicity.
  
  
  METHODS
  The analysis was conducted on the medical history of 370 patients who were treated with anthracycline-based chemotherapy between 2006 and 2012 in the Clinical Oncology Department, Maria Sklodowska-Curie Memorial Cancer Centre and Institute of Oncology in Gliwice in Poland (COI). All patients were tested for the presence of BRCA1 and BRCA2 mutations.
  
  
  RESULTS
  In the studied group 13% (48) of the patients were BRCA mutation carriers. Neutropaenia after the first cycle of chemotherapy occurred more commonly in mutation carriers compared to non-carriers (29% vs. 10%), p = 0.0002. Radiotherapy acute skin toxicity was present in 3% of patients with similar rates in both groups, p = 0.950. Toxicity grade 3-4 was present more frequently in patients younger than 70 years (p = 0.02) of age, patients with viral hepatitis (p = 0.045), hypertension (p = 0.039), and cardiovascular disease (p = 0.044). Lower WBC count before treatment was observed more frequently in patients with neutropaenia (p = 0.002), especially in mutation carriers, p = 0.0015.
  
  
  CONCLUSIONS
  Risk factors for anthracycline-based chemotherapy side effects were: age below 70 years, lower WBC value at baseline, history of infectious diseases, hypertension, and cardiovascular comorbidity. The presence of BRCA mutations may be a risk factor for neutropaenia, but it did not affect radiotherapy toxicity.
authors.affiliation: Clinical and Experimental Oncology Department, Maria Skłodowska-Curie Memorial Cancer Center and Institute of Oncology, Gliwice, Poland.
authors.forename: Joanna
authors.initials: J
authors.lastname: Huszno
authors.affiliation: Clinical and Experimental Oncology Department, Maria Skłodowska-Curie Memorial Cancer Center and Institute of Oncology, Gliwice, Poland.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Budryk
authors.affiliation: Clinical and Experimental Oncology Department, Maria Skłodowska-Curie Memorial Cancer Center and Institute of Oncology, Gliwice, Poland.
authors.forename: Zofia
authors.initials: Z
authors.lastname: Kołosza
authors.affiliation: Clinical and Experimental Oncology Department, Maria Skłodowska-Curie Memorial Cancer Center and Institute of Oncology, Gliwice, Poland.
authors.forename: Elżbieta
authors.initials: E
authors.lastname: Nowara
keywords: BRCA1/2 mutation; breast cancer; chemotherapy; radiotherapy; side effects