Summary Of Evidence

Significance

Evidence Of Benefit

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SUMMARY OF EVIDENCE

There is insufficient evidence to establish that screening would result in a decrease in mortality from oral cancer.

Level of Evidence: 5

Opinions of respected authorities based on clinical experience, descriptive studies, or reports of expert committees.

SIGNIFICANCE

More than 90% of oral cancers occur in patients over the age of 45. The incidence increases steadily with age until 65, when the rate levels off. Over the last 22 years, there have been slight decreases in incidence and mortality rates.

The primary risk factors for oral cancer in American men and women are tobacco (including smokeless tobacco) and alcohol use. Infection with HPV-16 virus has been associated with an excess risk of developing squamous cell carcinoma of the oropharynx.[3]

Oral cancer occurs in a region of the body that is generally accessible to physical examination by the patient, the dentist, and the physician. Screening examination can be made more efficient by inspecting the high-risk sites where 90% of all oral squamous cell cancers arise: the floor of the mouth, the ventrolateral aspect of the tongue, and the soft palate complex.[4] It has been pointed out that high-risk individuals visit their medical doctors more frequently than they visit their dentists. An inspection of the oral cavity is often part of a physical examination in a dentist's or physician's office. An oral examination often includes looking for leukoplakia and erythroplastic lesions, that can progress to cancer.[5] Recent data suggest that molecular markers may be useful as markers of prognosis for these pre-malignant oral lesions. [6,7]

Although easily detected and often cured in its early stages, most oral cancers are moderately advanced (regional stage) at the time of diagnosis. Unfortunately, this pattern has not changed over time.

References:

1. American Cancer Society: Cancer Facts and Figures-2002. Atlanta, Ga: American Cancer Society, 2002.
2. Ries LA, Kosary CL, Hankey BF, et al., eds.: SEER Cancer Statistics Review 1973-1995. Bethesda, Md: National Cancer Institute, 1998.
3. Mork J, Lie AK, Glattre E, et al.: Human papillomavirus infection as a risk factor for squamous-cell carcinoma of the head and neck. New England Journal of Medicine 344(15): 1125-1130, 2001.
4. Mashberg A, Barsa P: Screening for oral and oropharyngeal squamous carcinomas. CA: A Cancer Journal for Clinicians 34(5): 262-268, 1984.
5. Chiodo GT, Eigner T, Rosenstein DI: Oral cancer detection: the importance of routine screening for prolongation of survival. Postgraduate Medicine 80(2): 231-236, 1986.
6. Sudbo J, Kildal W, Risberg B, et al.: DNA content as a prognostic marker in patients with oral leukoplakia. New England Journal of Medicine 344(17): 1270-1278, 2001.
7. Poh CF, Zhang L, Lam WL, et al.: A high frequency of allelic loss in oral verrucous lesions may explain malignant risk. Laboratory Investigation 81(4): 629-634, 2001.

EVIDENCE OF BENEFIT

In Sri Lanka and India, 3 large studies of screening for oral cancer (involving over 250,000 subjects) have shown that it is possible for primary health care workers to detect premalignant lesions and early cancers in these populations at high risk due to habits of tobacco and betel nut chewing and reverse smoking (placing the lit end of the cigarette in the mouth).[3-5] The general results of these studies were as follows: 1) 12% to 26% of screened participants had oral lesions that did not require referral to a specialist; 2) 1.3% to 4.2% of screened subjects had referable oral mucosal lesions, and of these, 45% to 80% were correctly referred; 3) the false positive rate ranged from 9% to 29%; and 4) primary health care workers detected a total of 44 new oral cancers.

Compliance rates of these studies varied from 54% to 72%, and poor compliance following initial screening make feasibility of these types of studies uncertain. Health education programs only marginally increased compliance rates. Compliance problems of the Indian and Sri Lankan studies are likewise a possibility in the United States and other countries, which also have experienced suboptimal compliance among high-risk tobacco and alcohol users.[6] Contradictory oral cancer screening recommendations have been issued by the U.S. Preventive Health Services Task Force (against) and the American Dental Association (for), illustrating the complexity of the issue.[1] Oral exfoliative cytology is the most extensively studied screening procedure of U.S. oral screening programs. Problems encountered with this screening method include a high proportion of false-negative examinations and poor voluntary participation by the highest-risk individuals (heavy tobacco and alcohol users).

References:

1. Screening for oral cancer. In: Fisher M, Eckhart C, eds.: Guide to Clinical Preventive Services: an Assessment of the Effectiveness of 169 Interventions. Report of the U.S. Preventive Services Task Force. Baltimore, Md: Williams & Wilkins, 1989, pp 91-94.
2. Antunes JP, Biazevic MH, deAraujo ME, et al.: Trends and spatial distribution of oral cancer mortality in Sao Paulo, Brazil. Oral Oncology 37: 345-350, 2001.
3. Warnakulasuriya KA, Nanayakkara BG: Reproducibility of an oral cancer and precancer detection program using a primary health care model in Sri Lanka. Cancer Detection and Prevention 15(5): 331-334, 1991.
4. Mehta FS, Gupta PC, Bhonsle RB, et al.: Detection of oral cancer using basic health workers in an area of high oral cancer incidence in India. Cancer Detection and Prevention 9(3-4): 219-225, 1986.
5. Warnakulasuriya KA, Ekanayake AN, Sivayoham S, et al.: Utilization of primary health care workers for early detection of oral cancer and precancer cases in Sri Lanka. Bulletin of the World Health Organization 62(2): 243-250, 1984.
6. Prout MN, Sidari JN, Witzburg RA, et al.: Head and neck cancer screening among 4611 tobacco users older than forty years. Otolaryngology - Head and Neck Surgery 116(2): 201-208, 1997.

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