Cellular Classification of Oropharyngeal Cancer

Most oropharyngeal cancers are squamous cell carcinomas (SCCs).[1,2] Other oropharyngeal cancers include:

• Minor salivary gland tumors.
• Lymphomas.
• Lymphoepitheliomas (e.g., tonsillar fossa).

(Refer to the PDQ summaries on Salivary Gland Cancer Treatment, Adult Hodgkin Lymphoma Treatment, and Adult Non-Hodgkin Lymphoma Treatment for more information.)

SCCs may be noninvasive or invasive. For noninvasive SCC, the term carcinoma in situ is used. Histologically, invasive carcinomas are well-differentiated, moderately differentiated, poorly differentiated, or undifferentiated. SCCs are usually moderately or poorly differentiated.[2] Grading the deep invasive margins (i.e., invasive front) of SCC may provide better prognostic information than grading of the entire tumor.[3]

Immunohistochemical examination of tissues for the expression of the biomarker Ki-67, a proliferation antigen, may complement histologic grading. As a molecular indicator of epithelial dysplasia of the oropharynx, Ki-67 expression appears to correlate well with loss of heterozygosity (LOH) in tumor cells. In a retrospective study involving 43 tissue samples from 25 patients, the assessment of proliferation with Ki-67 was found to be a better surrogate for LOH than histologic grading.[4]

Leukoplakia should be used only as a clinically descriptive term meaning that the observer sees a white patch that does not rub off, the significance of which depends on the histologic findings.[5] Leukoplakia can range from hyperkeratosis to an actual early invasive carcinoma or may only represent a fungal infection, lichen planus, or other benign oral disease. (Refer to the General Information About Oropharyngeal Cancer section of this summary for more information.)

1. Mendenhall WM, Werning JW, Pfister DG: Treatment of head and neck cancer. In: DeVita VT Jr, Lawrence TS, Rosenberg SA: Cancer: Principles and Practice of Oncology. 9th ed. Philadelphia, Pa: Lippincott Williams & Wilkins, 2011, pp 729-80. 
   
   
2. Oral cavity and oropharynx. In: Rosai J, ed.: Ackerman's Surgical Pathology. 8th ed. St. Louis, Mo: Mosby, 1996, pp 223-55. 
   
   
3. Bryne M, Boysen M, Alfsen CG, et al.: The invasive front of carcinomas. The most important area for tumour prognosis? Anticancer Res 18 (6B): 4757-64, 1998 Nov-Dec.  [PUBMED Abstract]
   
   
4. Tabor MP, Braakhuis BJ, van der Wal JE, et al.: Comparative molecular and histological grading of epithelial dysplasia of the oral cavity and the oropharynx. J Pathol 199 (3): 354-60, 2003.  [PUBMED Abstract]
   
   
5. Neville BW, Day TA: Oral cancer and precancerous lesions. CA Cancer J Clin 52 (4): 195-215, 2002 Jul-Aug.  [PUBMED Abstract]