Aim Team performance is important in multidisciplinary teams (MDTs), but no tools exist for assessment. Our objective was to construct a robust tool for scientific assessment of MDT performance.

Materials and methods An observational tool was developed to assess performance in MDTs. Behaviours were scored on Likert scales, with objective anchors. Five MDT meetings (112 cases) were observed by a surgeon and a psychologist. The presentation of case history, radiological and pathological information, chair's effectiveness, and contributions to decision-making of surgeons, oncologists, radiologists, pathologists and clinical nurse specialists (CNSs) are analysed via descriptive statistics, a comparison of average scores (Mann–Whitney U) to test interobserver agreement and intraclass correlation coefficients (ICCs) to further assess interobserver agreement and learning curves.

Results Contributions of surgeons, chair's effectiveness, presentation of case history and radiological information were rated above average (p≤0.001). Contributions of histopathologists and CNS were rated below average (p≤0.001), and others average. The interobserver agreement was high (ICC=0.70+) for presentation of radiological information, and contribution of oncologists, radiologists, pathologists and CNSs; adequate for case history presentation (ICC=0.68) and contribution of surgeons (ICC=0.69); moderate for chairperson (ICC=0.52); and poor for pathological information (ICC=0.31). Average differences were found only for case-history presentation (p≤0.001). ICCs improved significantly in assessment of case history, and Oncologists, and ICCs were consistently high for CNS, Radiologists, and Histopathologists.

Conclusions Scientific observational metrics can be reliably used by medical and non-medical observers in cancer MDTs. Such robust assessment tools provide part of a toolkit for team evaluation and enhancement.