CTF Structured Abstract: Prevention of oral cancer

Canadian Task Force on Preventive Health Care

Structured Abstract

Please note: In 2003, the CTF updated its Grades of Recommendations to include an "I Recommendation" for situations where insufficient evidence exists to allow a recommendation to be made. (Formerly, these situations were captured under a "C Recommendation".) This change is not retroactive, and all "C Recommendations" made prior to 2003 have not been reevaluated in light of the new "I" recommendation grade. For a discussion of these recommendation grades, please link to the 2003 article in the Canadian Medical Association Journal here.

Prevention of Oral Cancer

Prepared by Carl Rosati, MD, FRCSC, Geberal Surgery, North York Branson Hospital, North York, Ontario

These recommendations were finalized by the Task Force in June 1993

Objective
Burden of Suffering
Options
Outcomes

Evidence
Values
Benefits, Harms, and Costs
Recommendations

Validation
Sponsors
Selected References

Objective

To make recommendations about screening for and prevention of oral cancer among the general population in Canada. This updates a 1979 report.

Burden of Suffering

The estimated incidence of oral cancers in Canada in 1993 was 3,120 and they accounted for 1,100 deaths, approximately 1.9% of all cancer deaths. The lifetime probability of developing and dying from oral cancers in men is 1.71% and 0.61% and for women is 0.71% and 0.27%, respectively. The potential years of life lost (PYLL) for oral cancer was 16,000 years in Canada in 1989. Cancer rates for both the salivary gland and nasopharynx are 10-25 times higher among the Inuit than among the general Canadian population; these cancers are associated with Epstein-Barr virus infection as well as genetic, environmental and immunologic factors. Risk factors for oral cancer include smoking, alcohol consumption, and smokeless tobacco (long-term users of smokeless tobacco are 50 times more likely to develop cancer of the cheek and gum than non-users).

There is psychosocial disability in terms of appearance, self-esteem and withdrawal from familial and other social interactions. There are physical and functional disabilities in terms of personal hygiene, swallowing and maintenance of nutritional status, speaking and therapy-specific morbidities related to radical neck dissection and irradiation, thyroid and parathyroid dysfunction, mouth dryness from lack of normal secretion, osteonecrosis of facial bones and the adverse effects of chemotherapy.

Options

To screen or not to screen using oral physical examination or oral physical examination plus tolonium chloride testing; smoking cessation counselling. Treatment of oral premalignancies includes 13-cis-retinoic acid (13cRA) and b -carotene; treatment of invasive cancers includes surgery or radiation.

Outcomes

Properties of screening measures included sensitivity, specificity, positive and negative predictive values, cost-effectiveness and adverse effects. Treatment effectiveness outcomes included survival, remission of leukoplakia (premalignancy), occurrence of second primary oral cancer and adverse effects.

Evidence

MEDLINE was searched for English-language articles published between 1980 to 1993 using the keywords mouth neoplasms, health status indicators, population surveillance, mass screening combined with evaluation studies, outcome and process assessment, mortality and prognosis.

Recommendations were graded as:

A Good evidence to support the recommendation that the condition be specifically considered in a PHE.

B Fair evidence to support the recommendation that the condition be specifically considered in a PHE.

C Poor evidence regarding inclusion or exclusion of the condition in a PHE, but recommendations may be made on other grounds.

D Fair evidence to support the recommendation that the condition be specifically excluded from consideration in a PHE.

E Good evidence to support the recommendation that the condition be specifically excluded from consideration in a PHE.

Quality of evidence was rated according to 5 levels:

I Evidence from at least 1 properly randomized controlled trial (RCT).

II-1 Evidence from well-designed controlled trials without randomization.

II-2 Evidence from well-designed cohort or case-control analytic studies, preferably from more than 1 centre or research group.

II-3 Evidence from comparisons between times or places with or without the intervention. Dramatic results in uncontrolled experiments could also be included here.

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

Values

The 13-member Task Force of experts in family medicine, geriatric medicine, pediatrics, psychiatry and epidemiology used an evidence-based method for evaluating the effectiveness of preventive health care interventions. Recommendations were not based on cost-effectiveness of options. Patient preferences were not discussed.

Background papers providing critical appraisal of the evidence and tentative recommendations prepared by the chapter author were pre-circulated to the members. Evidence for this topic was presented and deliberated upon in 1- to 2-day meetings, 2 to 3 times per year from January 1993 to June 1993. Consensus was reached on final recommendations.

Benefits, Harms, and Costs

A meta-analysis of RCTs found that the use of multiple smoking cessation interventions (including cessation counselling) increased cessation rates. Some of these studies demonstrated a corresponding reduction in oral cancer rates.

No RCTs evaluated the effectiveness of oral cancer screening. Cohort and case-control studies reported sensitivities of 59% to 100% and specificities of 95.9% to 99.7% for oral examination. When combined with tolonium chloride testing, average sensitivities of 96.7% and specificities of 90.8% are reported. Adverse effects of false positive results include negative psychological effects of labelling and added costs of continued investigation. Low positive predictive values and low prevalence of oral cancers limit the usefulness of screening measures.

No studies of the cost-effectiveness studies of screening programs have been undertaken.

2 RCTs of the primary treatment of oral leukoplakia (asymptomatic pre-cancer) and therapy to prevent second primary lesions using 13cRA reported a reduction in relative risk to almost 1.0 for complete remission of leukoplakia, and to 0.83 for occurrence of second primary oral cancers. However, patients relapsed 3 to 6 months after discontinuation, and rates of adverse effects of up to 79% were reported. Treatment with b -carotene resulted in reductions of up to 71% in oral leukoplakia and mucosal dysplasia, but to a lesser degree than with 13cRA. Virtually no adverse effects were reported.

Radiation and surgical treatments of invasive oral cancers appear to have similar survival rates. Cancer stage is an important prognostic factor.

Recommendations

Recommendation grade [A, B, C, D, E] and level of evidence [I, II-1, II-2, II-3, III] are indicated after each recommendation. Citations in support of individual recommendations are identified in the guideline text.

There is good evidence to include (in the PHE) smoking cessation counselling [A, I]. *Although the recommendation has not changed, the evidence review has been updated for this recommendation.
Link to recommendation table for 1999 update: Prevention of oral cancer mortality
There is insufficient evidence to include or exclude routine screening by oral examination [C, I, II-2, III]. However, annual examination by a physician and/or dentist should be considered for patients >60 years with risk factors (e.g., tobacco use). Individual judgment should be used regarding the use of tolonium chloride for those with positive oral examination results. *Note: This recommendation has been updated.
Link to recommendation table for 1999 update: Prevention of oral cancer mortality

Validation

This report was externally peer reviewed. Recommendations and background papers were sent for external peer review. Recommendations are consistent with those of the 1989 U.S. Preventive Services Task Force. The Canadian and American Dental Associations make no specific recommendations regarding oral cancer screening.

Selected References

Source Document

Rosati C. Prevention of oral cancer. In: Canadian Task Force on the Periodic Health Examination. Canadian Guide to Clinical Preventive Health Care. Ottawa: Health Canada, 1994; 826-36.

Link to Full Text of this review

Link to Summary Table of Recommendations of this review

Link to Selected References list of this review

Link to 1999 Update: Prevention of oral cancer mortality

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A	Good evidence to support the recommendation that the condition be specifically considered in a PHE.
B	Fair evidence to support the recommendation that the condition be specifically considered in a PHE.
C	Poor evidence regarding inclusion or exclusion of the condition in a PHE, but recommendations may be made on other grounds.
D	Fair evidence to support the recommendation that the condition be specifically excluded from consideration in a PHE.
E	Good evidence to support the recommendation that the condition be specifically excluded from consideration in a PHE.

I	Evidence from at least 1 properly randomized controlled trial (RCT).
II-1	Evidence from well-designed controlled trials without randomization.
II-2	Evidence from well-designed cohort or case-control analytic studies, preferably from more than 1 centre or research group.
II-3	Evidence from comparisons between times or places with or without the intervention. Dramatic results in uncontrolled experiments could also be included here.
III	Opinions of respected authorities, based on clinical experience, descriptive studies or reports of expert committees.