Frequency and risk factors of potential drug interactions in breast cancer patients

Objective: Breast cancer is the most common cancer in women. Breast cancer is seen in one of every six women during their lifetime period. It's mostly seen at older ages. In addition to cytotoxic treatment, these patients use various medication for hormonal treatment, treatment of comorbid diseases and palliative treatment. Due to this polydrug treatment, patients are at high risk of potential drug interactions. In our study we aimed to evaluate frequency, severity, clinical importance and risk factors of drug interactions in breast cancer patients. Material?Method: 200 breast cancer patients who applied to İnönü University Medical Faculty Turgut Özal Hospital's medical oncology inpatient and outpatient clinics are included to this study. Patient's demogrofical features, their treatment regimen, comorbid diseases and other medication being used in purpose of supportive treatment are gathered with a questionnaire. The web-based ''interaction checker '' programme, "www.medscape.com", is used to detect drug interactions and classify them in the order of importance. Findings: %99 of all patients was female and %1 was male. Median age was 51.26. Median number of drugs that patietns use was found as 3. %93,5 of patients was outpatient and %6,5 of them was inpatient. Mean number af drugs that outpatients use was 3,47; and that inpatients use was 5,15. Also median drug interaction was 1,58 for outpatients and 4,58 for inpatients. At least one comorbidity was detected in %52 of all patients and %94 of patients were on palliative treatment. When these comorbid diseases are evaluated further, %22 of them found as hypertension and %15,5 of them found as diabetis mellitus. Potential drug interaction was identified in %83,7 of patients who have comorbidities. When drug groups are overwieved, %68 of interactions were between antineoplastics and %14,5 of them was between comorbidity drugs. %80 of patients had at least one drug interaction. %72,5 of these interactions were moderate, %20,1 was minor and %4,3 was severe. Number of drugs used, being inpatient and existance of comorbidity were detected to increase drug interactions according to multivariate analysis (p<0.01). Result: Breast cancer patients are using polydrug treatments due to their prolonged survial, their comorbid diseases and elder emergence of the disease. Potential drug interactions are commonly seen in these patients, therefore their entire medication regimen should be investigated before starting any treatment. Number of drugs that are being used, existance of comorbidity and being inpatient are the risk factors for drug interactions. Keywords: Breast cancer, drug interactions, risk factors ?