Cancer of the oral cavity and pharynx in Karachi--identification of potential risk factors.

The objective of the study was to provide an overview of the demographics of cancer of the oral cavity and pharynx in Karachi South (1995-2001), and identify potential risk factors. Cases recorded for Karachi South, at Karachi Cancer Registry during 1(st) January 1995 to 31(st) December 2002 were analysed. For maximum completion of data cancer cases, recorded from 1(st) January 1995 to 31(st) December 2001 were included for final analysis. The age standardized incidence rates per 100000 population (ASIRs) for cancer of the oral cavity (excluding salivary gland) in Karachi South were 17.1 and 16.5 in males and females whereas the ASIRs for cancer of the pharynx (excluding nasopharynx) were 7.1 and 2.4 in males and females, respectively. The oral pharyngeal ratios were 2.4 and 6.9 for males and females and gender ratios (M F) were 1.04 for the oral cavity and 3.0 for the pharynx. The mean ages were 51 years (95% CI 49.6; 52.2) and 56.1 years (95% CI 54.4; 57.8) respectively. Cancer of the oral cavity ranked 2(nd) in Karachi in both genders. Cancer of the pharynx ranked 7(th) in males and 14(th) in females. Approximately 97% of the oral cavity and pharyngeal cancers were histologically confirmed. The majority of the oral (47.1%) and pharyngeal (51.9%) cancer cases presented as grade II lesions, and were discovered at advanced stages. Of the cancers reported during 1995-2001, 60.4% of the oral and 78.1% of the pharyngeal lesions had spread to a distant site at the time of diagnosis. Squamous cell carcinoma comprised 96.5% and 91.8% of the totals. The incidences of these cancers are comparable to the highest risk regions of the world. As distinct from other geographical areas oral cancer is as common in females as in males, which may reflect the pattern of exposure to known risk factors such as betal quid, arecanut and tobacco and the absence of alcohol as a risk factor in both genders. Apergillus contamination of arecanut could also be a risk factor but no confirmation studies or quantification is available. Despite the common risk factors, incidence of pharyngeal cancer is three times higher in men as compared with women. The keys to reducing the incidence and mortality due to oral and pharyngeal cancers are prevention and control, emphasizing cessation of tobacco use and cancer screening. However a targeted cancer and tobacco control program does not presently exist in Pakistan.