Decisional support is a multifaceted process of facilitating patients' decision making regarding treatment choices. Effective decisional support practices of nurses in relation to the use of anticancer therapies in patients with advanced disease are central to quality cancer care. A recent qualitative descriptive study (n=21) exploring the decision making practices of doctors and nurses in one tertiary cancer centre in New Zealand identified many complexities associated with nurses and their participation in decisional support. The study revealed that cancer nurses had varied opinions about the meaning and importance of their roles in treatment related decision making. This variation was significant and led the researchers to undertake a detailed secondary exploration of factors that impacted on the nurses' involvement in the provision of decisional support. Four key groups of factors were identified. These were factors relating to degree of knowledge, level of experience, beliefs and understandings about nursing roles and cancer therapies, and structural interfaces in the work setting. Understanding these factors is important because it allows modification of the conditions which impact on the ability to provide effective decisional care. It also provides some understanding of clinical drivers associated with nurses' decisional support work with patients who have advanced cancer.