AbstractBackgroundMultidisciplinary team meetings (MDTMs), where treatment recommendations are discussed and agreed, are fundamental to effective cancer care. The increasing volume and complexity of caseloads has led to the need to transform MDTM pathways to improve efficiency and allow sufficient time for discussion of complex cases. Understanding of current functioning and inefficiencies is required to inform such transformation.MethodsA mixed‐methods observational study of all lung cancer MDTMs in one UK cancer network over 12 weeks (n= 8 MDTs, 96 MDT meetings). Data were collected on meeting attendance and on each discussed case using a validated MDT tool. Semi‐structured interviews were conducted with a range of MDT members and cancer service managers to gain understanding of perceived influences on the efficiency of MDTMs.ResultsIn total, 1671 case discussions were observed. Models of MDT working, including referral and diagnostic pathway management, varied within the network. Attendance was quorate in only 21% of the observed MDTMs, most often lacking palliative care specialists. Over a third (37%) of observed cases were repeat discussions pre‐diagnosis. Treatment recommendations were agreed in 48% of case discussions but deferred for a quarter (24%) of discussed cases, most commonly due to awaiting results. Information about patients' fitness for treatment and/or performance status score was available for 60% of cases discussed overall (30%–75% by MDT). Interviews (n= 56) identified addressing clinical and administrative workforce shortages, less reliance on the MDTM for pre‐diagnostic decision‐making and better availability of key clinical information about patients discussed in the MDTM as factors critical to improved MDT function.ConclusionsInefficiencies were prevalent in all MDTMs; improvements would require an individualised approach due to the variation in ways of working. Local, regional and national support is needed for lung MDTs to develop their diagnostic workforce and facilities, and clinical and administrative resource.