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 ¹, Adult Hodgkin Lymphoma Treatment ², and Adult Non-Hodgkin Lymphoma Treatment ³ 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 ⁴ section of this summary for more information.)

References

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]