tailieunhanh - Cancer Medicine 5_2

Tham khảo sách 'cancer medicine 5_2', y tế - sức khoẻ, y học thường thức phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Section 27 Neoplasms of the Head and Neck 86 head and neck cancer Gary L. Clayman MD Scott M. Lippman MD George E. Laramore MD Waun Ki Hong MD The American Cancer Society ACS predicted that in 1999 approximately 40 400 new cases of head and neck cancer would be diagnosed in the United States 29 800 with oral cavity and pharyngeal cancer and 10 600 with laryngeal cancer . The same grim reckoning projected 12 300 American deaths in 1999 from this class of These diagnosis and mortality figures correspond to over 4 of all new cancer cases and 2 of all cancer deaths in the United States annually. Nearly identical percentages are reported from Britain but head and neck cancers have a much greater impact in certain other parts of the world and are among the leading causes of cancer mortality 3 Despite improvements in diagnosis and local management long-term survival rates in head and neck cancer have not increased significantly over the past 30 years and are among the lowest worldwide of the major cancers. For African Americans survival rates have decreased. Oropharyngeal cancer the largest subgroup of head and neck cancers has a 5-year relative survival rate of only 55 for United States Caucasians and 32 for African Although early-stage head and neck cancers especially laryngeal and oral cavity have high cure rates over 60 of head and neck cancer patients present with advanced disease. Cure rates decrease of course in locally advanced cases whose probability of cure is inversely related to tumor size and even more so to the extent of regional node involvement. Treatment advances have been undermined by the significant percentage of patients initially cured of head and neck squamous cell carcinoma HNSCC who go on to develop second primary 6 Second primaries are the major threat to long-term survival after successful therapy of early-stage HNSCC. Their high incidence probably results from the same carcinogenic exposure .