External peer review was introduced in general hospitals in the Netherlands in 1994 to assess and improve the multidisciplinary team approach in cancer care. This paper aims to explore the value, perceived impact, and (future) role of external peer review in cancer care. Semistructured interviews were held with clinicians, oncology nurses, and managers from fifteen general hospitals that participated in three rounds of peer review over a period of 16 years. Interviewees reflected on the goals and expectations, experiences, perceived impact, and future role of external peer review. Transcriptions of the interviews were coded to discover recurrent themes. Improving clinical care and organization were the main motives for participation. Positive impact was perceived on multiple aspects of care such as shared responsibilities, internal prioritization of cancer care, improved communication, and a clear structure and position of cancer care within general hospitals. Establishing a direct relationship between the external peer review and organizational or clinical impact proved to be difficult. Criticism was raised on the content of the program being too theoretical and organization-focussed after three rounds. According to most stakeholders, external peer review can improve multidisciplinary team work in cancer care; however, the acceptance is threatened by a perceived disbalance between effort and visible clinical impact. Leaner and more clinically focused programs are needed to keep repeated peer reviews challenging and worthwhile.