Most oral cancers lack early symptoms that would prompt a patient to seek diagnosis; hence at presentation more than 60% of patients are diagnosed with stage III or IV advanced disease. Survival rates and morbidity are dramatically improved if the disease is treated at an early stage, preferably asymptomatic in stage one. Therefore, early detection of oral cancer and oral potentially malignant lesions in the asymptomatic phase via an oral cancer screening examination is important.The core objective of this thesis is to determine whether asymptomatic diagnosis of oral cancer at an early stage of disease is achievable in Australia. We achieve this by evaluating the awareness of, and attitudes toward, oral cancer and opportunistic screening held by recently-diagnosed oral cancer patients, experienced general medical practitioners, and recentlygraduated medical students. From these studies we found that participants with oral cancer had poor awareness of oral cancer and poor knowledge of risk factors prior to diagnosis. Nearly all were over 40 years of age and most consumed tobacco or alcohol or both, suggesting a target population for opportunistic screening in the primary healthcare setting. Patient, professional, and total diagnostic ii delay were better than in many other countries. In the asymptomatic phase before diagnosis, participants with oral cancer were more likely to visit a GMP over a General Dental Practitioner (GDP), and likely to do so multiple times each year, identifying significant opportunities for GMPs to perform opportunistic oral cancer screening.We also found that Australian GMPs and GMSs have an inadequate level of knowledge of oral cancer, OPMLs, risk factors, and inadequate skill in performing opportunistic oral cancer screening examinations. At the present level of knowledge and confidence, it would be unlikely for a GMP to conduct a thorough visual and tactile oral cancer screening examination even if a highrisk individual presented to his or her clinic. Only 7% of participants with oral cancer were diagnosed in the asymptomatic phase, and all were diagnosed by health practitioners with a dental qualification.We conclude that asymptomatic diagnosis of oral cancer at an early stage of disease is achievable in the primary medical healthcare setting in Australia via opportunistic oral cancer screening. Initiating a consultation with a GMP or GDP for an oral cancer screening examination would require a patient to have an improved awareness of oral cancer and knowledge of his or her personal risk factors for developing it. To increase opportunistic oral cancer screening activity from Australian GMPs, interventions need to ensure that GMPs and GMSs reach competence in risk factors for oral cancer, identifying high-risk populations, diagnostic confidence, and skill in performing the nine-step visual and tactile opportunistic oral cancer screening examination.iii