Several epidemiological studies suggest that bidi smoking increases the risk of oral cancer. No systematic review, however, has been reported to examine how consistent the evidence is across the studies. We undertook a meta-analysis of epidemiological studies investigating the relationship between bidi smoking and oral cancer. Primary studies were identified through a computerized literature search of Med Cancer of the oral cavity and pharynx combined account for approximately 5% of all cancer in men (220,000 new cases per year) and 2% of all cancer in women (90,000 new cases per year) in the world. 1 In some parts of the world, incidence rates of cancers of oral cavity and pharynx in men even exceed those for any other cancers. As is often the case with other kinds of cancer, oral cancer incidence and mortality rates vary widely across the region, but the highest rates being generally observed in a specified developing region, India, Pakistan and Bangladesh, where this is the most common form of cancer. 2,3 Oral cancers coded according to International Classification of Disease version 10 (ICD-10) as C00-14 (cancer of lip, tongue, salivary glands, mouth, oropharynx, nasopharynx and hypopharynx), are grouped together to improve comparability between the countries, although some of the rarest subsites, cancer of lips (associated with ultraviolet rays exposure besides tobacco) and salivary glands (not straightly related to tobacco or alcohol), have different etiologies. 4 Tobacco and alcohol are identified as important risk factors for oral cancer in developed countries. 4,5 Tobacco, smokeless tobacco, betel-nuts and oral hygiene may have important role in the developing world.Bidi, an age-old form of indigenous smoking is used widely by the people of lower socioeconomic status in India, Bangladesh, Nepal, Pakistan and other south Asian countries. 6 It is made of about 0.2-0.5 g raw, dried and crushed tobacco flakes (naturally cured) rolled by hand in tendu leaf (Diospyrus mebunoxylon or Diospyrus ebenum) or white paper. 6 Nicotine and tar content are higher in bidi than that of a cigarette. 6 Although some studies found an association between bidi smoking and oral cancer, the results of the previous studies are not consistent. The objectives of our study were to quantify the association between bidi smoking and oral cancer, and to compare it with that of cigarette smoking.
MATERIAL AND METHODSWe conducted a literature search using Medline database for articles related to bidi smoking and oral cancer published between January 1966 and June 2002. Medline was searched in April 2002 using the words bidi, beedi, cancer, oral cavity, oral cancer and smoking. The Cochrane Library was also searched for the related studies and meta-analysis on the same topic, but no studies were identified. Studies were included in the meta-analysis if they reported data on association between bidi smoking as an exposure variable and any of the variety of oral cancer as an outcome variable. References listed in the retrieved articles and ...