Overall, the five-year survival rate for oral cancer is 40-50%. Generally, the further anterior in the mouth the tumor occurs the better the prognosis. For example, over 90% of patients with cancer of the lower lip can expect a cure. For cancers involving the posterior tongue that are not associated with HPV16, the rate can be less than 30%. The presence of tumor in regional lymph nodes further reduces the overall 5-year survival rate by one-half. The continued use of tobacco after treatment for oral cancer increases the risk of recurrence. Patients with HPV16 associated carcinoma have a higher 5-year survival rate showing excellent response to radiation and chemotherapy provided the patient has a less than 10 pack year history of tobacco use. In addition, all patients who have had cancer of the head and neck have a 5% risk per year of developing another tumor in the head and neck (second primary).