Many factors can lead to the development of laryngeal cancer, including certain viruses such as human papilloma virus (HPV), but approximately 90 percent of head and neck cancers occur after exposure to known cancer-causing substances, called carcinogens. Chief among these factors is tobacco. Over 90 percent of laryngeal cancers are a type of cancer called squamous cell carcinoma (SCCA), and over 95 percent of patients with laryngeal SCCA are smokers. Smoking contributes to cancer development by causing mutations or changes in genes, preventing carcinogens from being cleared from the respiratory tract, and decreasing the body’s immune response.
Tobacco use is measured in pack-years. For example, two pack-years is defined as either one pack per day for two years, or two packs per day for one year (longer terms of pack-years are determined using a similar ratio). Depending upon the number of pack-years smoked, studies have reported that smokers are about five to 35 times more likely to develop laryngeal cancer than non-smokers. The longer you are exposed to tobacco is probably more important to developing cancer than the intensity of the exposure.
Alcohol is another important risk factor for laryngeal cancer because it promotes the cancer-causing process, especially in the presence of tobacco. People who smoke and drink alcohol have a combined risk that is greater than the sum of the individual risks. Other risk factors for laryngeal cancer include HPV and acid reflux.