Cancer of the tongue is classified with oral cancers which are relatively rare and account for about 3% of all forms of cancer. This form of cancer is more common in men. However, in the past twenty years, the number of cases among women has increased greatly. Oral cancer occurs in three principle areas, the lips, the oral cavity, which includes the front two-thirds of the tongue, and the oropharynx, which emcompasses the middle part of the pharynx, the back third of the tongue, the soft palate, the side and back walls of the throat, and the tonsils.
The first prospective investigation of the link between burning incense and the increased risk of developing cancer of the oral cavity and the lungs was conducted by Dr. Jeppe T. Friborg and his colleagues.
Dr. Friborg and his fellow researchers in the epidemiology department of Statens Serum Institut in Copenhagen, Denmark conducted the study with 61,320 Chinese residents in Singapore. The age of the participants ranged from forty-five to seventy-four. None had been diagnosed with cancer prior to enrollment in the research. Detailed interviews were conducted to include dietary and lifestyle habits, specifically the exposure to incense. Approximately three quarters of the subjects reported current incense use. The initial interviews were conducted between 1993 and 1998. The participants were followed until 2005.
The research team linked the intensity and duration of incense use to the increased level of risk in developing cancer. Long-term and frequent exposure to incense fumes almost doubles the risk of squamous cell carcinomas in the upper respiratory tract, such as the nose and sinuses, tongue, mouth, and larynx. The overall risk of developing lung cancer did not appear to increase with incense use but the analysis suggests a correlation to an increase risk of squamous cell carcinoma of the lung.
When incense is burned, some of the same carcinogens, which are found in cigarette smoke, such as polyaromatic hydrocarbons (PAHs), carbonyls and benzene are emitted and get trapped in the lungs.