Purpose The burden of cancer in Africa is an enlarging public health challenge. Breast cancer in Ghana is the second most common cancer among Ghanaian women and the proportion of diagnosed patients who complete prescribed treatment is estimated to be very limited, thereby potentially adding to lower survival and poor quality of life after diagnosis. The objective of this study was to identify the patient and system factors related to incomplete treatment of breast cancer among patients. Methods This study was conducted at the Komfo Anokye Teaching Hospital in Kumasi, Ghana. We interviewed 117 breast cancer patients and next of kin of breast cancer patients diagnosed from 2008 to 2010. Results Islamic religion, seeking treatment with traditional healers, and lack of awareness about national health insurance coverage of breast cancer treatment were predictors of incomplete treatment. Conclusions The results of this study support that Ghanaian women with diagnosed breast cancer have multiple addressable and modifiable patient factors that may deter them from completing the prescribed treatment. The results highlight the need for developing and testing specific interventions about the importance of completing treatment with a special focus on addressing religious, cultural, and system navigation barriers in developing countries.