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Brief Evidence Update
Prepared by Joe Cartoon, of the RTI-UNC Evidence-based Practice Center.
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Systematic reviews of the evidence serve as the basis for U.S. Preventive Services Task Force (USPSTF) recommendations on clinical prevention topics. The USPSTF tailors the scope of these reviews to each topic. The USPSTF determined that a brief, focused evidence review was needed to assist in updating its 1996 recommendations on on screening for oral cancer.1 Joe Cartoon, of the RTI-UNC Evidence-based Practice Center (under contract to Agency for Healthcare Research and Quality [AHRQ]), performed a targeted review of the literature published on this topic between 1994 and 2001.
The search strategy for this brief update included a MEDLINE® review for English-language articles published between 1994 and 2001 on new direct evidence on the benefits and harms of screening and treatment for oral cancer. MEDLINE® was searched for articles focusing on meta-analysis, systematic reviews, randomized controlled trials (RCT's), and controlled trials reporting demonstrable health outcomes (morbidity and mortality) in humans. The Cochran Library and National Guideline Clearinghouse™ were also searched for pertinent articles or recommendations.
The MEDLINE® search strategy combined the exploded MeSH® heading of Oral Neoplasm with Lip Neoplasm, Tongue Neoplasm, and Pharynx Neoplasm and crossed the result with Mass Screening, yielding 88 articles. These articles were further limited to RCT's by the exploded headings "randomized controlled trial/single-blind method/double blind method/random allocation." This approach identified one article. Limiting the search to reviews yielded 13 articles. A second search was conducted crossing the exploded MESH® headings of Mouth Neoplasm's or Oral Cancer with Therapeutics or Treatment, yielding 1,725 articles. Limiting the search to RCT's reduced the number of articles to 42. While none of these 42 addressed the key questions specifically, several were concerned with treatments for cancer precursors.
Key Questions and Results
Key Question 1: Does screening for oral cancer lead to decreased morbidity and mortality from oral cancer?
The ongoing, 2000 Kraal Trial in India is taking place in a cluster-randomized, controlled setting, with 59,894 subjects in the intervention group and 54,707 subjects in the control group.2 Subjects are 35 years or older. The intervention group will receive 3 rounds of screening (oral inspection by trained health workers) at 3-year intervals. The article by Ankara and colleagues2 was the result of the first interval. Forty-seven cancers (7 resultant deaths) were diagnosed in the intervention group and 16 cancers (9 resultant deaths) were diagnosed in the control group. The difference in case fatality between the 2 groups (14.9 percent and 56.3 percent) could potentially be attributed to lead-time bias.
Key Question 2: Is there new evidence of harms associated with screening for oral cancer?
No studies were identified that addressed harms associated with screening for oral cancer.
Key Question 3: Are there effective treatments for mitigating the morbidity/mortality of oral cancer if lesions are identified earlier rather than later?
No controlled studies examining treatment efficacy of early detection of oral cancer lesions were identified. Treatment of oral leucoplast, a form of pre malignancy, has been studied in RCT's with several modalities, demonstrating success at promoting remission; but the numbers of trial patients are small (10 to 59, ~50 for most) and there have been no long-term (>two years) follow up studies to assess the effects on cancer incidence or mortality.3-10
With the exception of the Kraal study,2 no controlled trials have been undertaken recently to demonstrate the effect of oral cancer screening on mortality or on interim outcomes (e.g., reducing the incidence on invasive disease). An update of this trial reports that after completing 2 rounds of screening, oral cancer mortality rates were similar in the screened and unscreened study groups.11 No other RCT's, meta-analyses, or systematic reviews were found on the harms of screening or the benefits of early treatment.
Recommendations of Professional Organizations
The American Cancer Society recommendation can be accessed at http://www.cancer.org.
The Canadian Task Force on Preventive Health Care recommendations can be accessed at http://www.ctfphc.org.
The American College of Obstetricians and Gynecologists recommendation is available in text form.12
1. U.S. Preventive Services Task Force. Guide to Clinical Preventive Services, 2nd ed. Washington, DC: Office of Disease Prevention and Health Promotion, 1996.
2. Ankara R, Mathew B, Jacob BJ, et al. Early findings from a community-based, cluster-randomized, controlled oral cancer screening trial in Kraal, India. The Trivandrum Oral Cancer Screening Study Group. Cancer 2000;88:664-73.
3. Femiano F, Gombos F, Scully C. Oral proliferative verrucous leukoplakia (PVL); open trial of surgery compared with combined therapy using surgery and methisoprinol in papillomavirus-related PVL. Int J Oral Maxillofac Surg 2001;30:318-22.
4. Gaeta GM, Gombos F, Femiano F, et al. Acitretin and treatment of the oral leucoplakias. A model to have an active molecules release. J Eur Acad Dermatol Venereol 2000;14:473-8.
5. Tete S, Pappalardo S, Rubini C, Salini L, Falco A, Perfetti EG. The role of apoptosis and bcl-2 protein in topical treatment of oral leukoplakia with isotretinoin. Minerva Stomatol 1999;48:411-8.
6. Piattelli A, Fioroni M, Santinelli A, Rubini C. bcl-2 expression and apoptotic bodies in 13-cis-retinoic acid (isotretinoin)-topically treated oral leukoplakia: a pilot study. Oral Oncol 1999;35:314-20.
7. Garewal HS, Katz RV, Meyskens F, et al. Beta-carotene produces sustained remissions in patients with oral leukoplakia: results of a multicenter prospective trial. Arch Otolaryngol Head Neck Surg 1999;125:1305-10.
8. Li N, et al. The chemopreventive effects of tea on human oral precancerous mucosa lesions. Proceedings of the Society for Experimental Biology and Medicine. 1999;220:218-224.
9. Benner SE, Lippman SM, Wargovich MJ, et al. Micronuclei, a biomarker for chemoprevention trials: results of a randomized study in oral pre-malignancy. Int J Cancer 1994;59:457-9.
10. Epstein JB, Wong FL, Millner A, Le ND. Topical bleomycin treatment of oral leukoplakia: a randomized double-blind clinical trial. Head Neck 1994;16:539-44.
11. Ramadas K, Sankaranarayanan R, Jacob BJ, et al. Interim results from a cluster randomized controlled oral cancer screening trial in Kerala, India. Oral Oncol 2003; 39(6):580-8.
12. Primary and preventive care: periodic assessments. ACOG Committee Opinion No. 292. American College of Obstetricians and Gynecologists. Obstet Gynecol 2003;102:1117-24.
This brief update and the updated recommendations of the USPSTF are available through the AHRQ Web site (http://www.uspreventiveservicestaskforce.org) and through the National Guideline Clearinghouse™ (http://www.guideline.gov).
Copyright Electronic Dissemination
This document is in the public domain within the United States. Requests for linking or to incorporate content in electronic resources should be sent via the USPSTF contact form.
Current as of February 2004
Scattoloni J. Screening for Oral Cancer: Brief Evidence Update. February 2004. http://www.uspreventiveservicestaskforce.org/3rduspstf/oralcan/oralcanup.htm