The lung cancer Optimal Care Pathway recommends supportive care and palliative care integration throughout its various steps, with early referral to appropriate services improving the quality of life in advanced stage non-small cell lung cancer patients. Using Victorian Lung Cancer Registry data and linked administrative datasets, this retrospective cohort study mapped clinical care pathways of 525 Stage III-IV non-small cell lung cancer patients in Victoria to 11 recommendations in the Optimal Care Pathway, identifying unwarranted variations in clinical care. Supportive care and palliative care delivery were further examined to understand the involvement and timing of specialist care teams. Our findings showed that palliative care utilization is highest at the time of treatment, despite recommendations that it should be provided early after diagnosis to improve patient outcomes and satisfaction. Early supportive care screening was observed in half the cohort and almost three-quarters of the patients had been presented at a multidisciplinary meeting. Multidisciplinary meeting presentations and supportive care provide an opportunity to improve communication about palliative care needs and integration into routine clinical practice, such as at the time of treatment planning.