Background: Chemotherapy improves tumour control and survival, but it may be associated with side effects (SEs) which can impair treatment compliance and worsen outcomes. Assessment of patients in routine clinical practice, outside clinical trials, may provide the information on effects of chemotherapy on patients and its impacts on treatment compliance.

Aim: To assess the SE and compliance to chemotherapy in breast cancer patients.

Methodology: A prospective study involving 120 breast cancer patients receiving chemotherapy was carried out at the oncology clinics of the University College Hospital Ibadan. SEs reported were recorded and graded using Common Toxicity Criteria for Adverse Events version 5. Compliance was defined as a receipt of planned cycles of chemotherapy in the planned doses within the planned duration. The data collected were analysed using the Statistical Package for the Social Sciences software version 25.

Results: The patients were all females with a mean age of 51.2 ± 11.8 years. Patients reported between 2 and 13 SE with a median of 8 SE. Forty-two (35.0%) missed at least one course of chemotherapy while 78 (65%) were compliant. The reasons for non-compliance were deranged blood test 17 (14.2%), chemotherapy SE symptoms related 11 (9.1%), financial constraints 10 (8.3%), disease progression 2 (1.7%) and transportation-related 2 (1.7%).

Conclusion: Breast cancer patients encounter multiple SEs from chemotherapy which led to non-compliance with the treatment. Early identification and prompt treatment of these SEs will improve compliance with chemotherapy.