Rising incidence of gastric malignancies in Karachi, 1995- 2002.

INTRODUCTION South Asia is an enigma for gastric cancer, a low risk region with a contradictory high prevalence for Helicobacter pylori. PATIENTS AND METHODS To examine the demographics, pathology and trends of gastric cancer in Pakistan, epidemiological data of 335 gastric malignancies, registered at Karachi Cancer Registry (KCR) for Karachi South (KS), during 1st January 1995 to 31st December 2002 were reviewed. Trends were studied by categorizing the cases into two time periods '1995-7' and '1998-2002'. RESULTS Ninety six cases of gastric cancers were registered in the 1995-7 period, 61 in males and 35 in females. In males, the ASR (world), and crude incidence rate (CIR) per 100,000 were 3.9 and 2.3 respectively. In females, the values were 3.0 and 1.5. In the 1998-02 period 239 cases of gastric cancer were registered, 156 cases in males and 83 in females. The ASR and CIR per 100,000 were 6.0 and 3.4 in males and 3.6 and 2.1 in females. An 18% increase was observed in males and 14% in females during the seven year study period. The male to female ratio was 2:1.The mean age of male patients was 51.9 years (95% CI 45.8; 58.1; SD -/+17.9) in 1995-7 and 53.7 years (95% CI 51.6; 55.9; SD -/+14.0) in 1998-02. In females the mean age for the two periods was 48.8 years (95% CI 42.5; 55.0; SD -/+ 18.2) and 48.4 years (95% CI 45.4; 51.5; SD -/+13.9) respectively. Age-specific curves showed a gradual increase in risk from the second until the seventh decade. The majority of the cases presented as poorly or moderately differentiated distal (non-cardia) cancers with a regional spread. CONCLUSION Gastric cancers in Karachi fall into the prototype of a low risk developing country pattern. The incidence is increasing, most marked in males above 40 years of age. Larger pathology-based studies are required to comment on the precise morphological sub-types of gastric adenocarcinoma. Etiological studies focused on different strains of H. pylori are required to address the gastric cancer enigma, whilst examining possible protective environmental or genetic factors.