Purpose Cancer multidisciplinary team (MDT) discussions are considered best practice, but they are resource intensive. To help determine if this is an effective use of resources, we aimed to quantify the degree to which MDT recommendations are implemented and review the reasons for deviation. Methods Thyroid cancer MDT notes and electronic medical records over a 5-year period were individually reviewed at a tertiary referral centre. The MDT recommendations were compared to the subsequently implemented practice for each case. Cases which diverged from MDT outcomes were classified into patient, clinician, disease, system and other factors. Results 80% of 1046 cases were referred and treated within our own institution, while the other 20% were from external practices. Cancer diagnosis had been confirmed in 79% prior to discussion, of which 15% were high risk cancers, and at least 28% demonstrated metastatic spread. 23% of cases were referred for MDT discussion prior to any treatment, 44% after surgery, and 33% after adjuvant therapy. Of the 875 in-house cases, the recommendations were fully implemented in 90.3%. Partial (5.5%) or non-implementation (4.2%) were due to patient preference in 30.6%, clinician preference in 12.9%, disease factors in 16.5%, system factors in 9.4%, and other factors in 30.6% (including lost to local follow-up, COVID-19-related barriers, patient death, or unable to determine). Surgical recommendations were almost always implemented. Conclusion This study shows that only 9.7% of MDT recommendations are not fully implemented, demonstrating the relevance and efficacy of this resource intensive practice. This research helps improve our understanding of the underlying patient, clinician and system factors that influence the implementation of MDT recommendations and further improve the service.