Patho-epidemiology of lung cancer in Karachi (1995-2002).

The objective of the study was to provide an overview of the demographics of lung cancer, the number one cancer killer of men in Karachi South (1995-2002). Lung cancer cases recorded at Karachi Cancer Registry during 1st January 1995 to 31st December 2004 were analyzed. To allow for maximum data completion, cases recorded from 1st January 1995 to 31st December 2002 were included for final analysis. Trends were studied by analyzing the age standardized incidence rates (ASR)s in 2 time periods, 1995-1997 and 1998-2002. Odds ratio for sex, age-groups, ethnicity, religion, and residence by socio-economic categories were calculated by considering all malignancies (except tobacco-associated malignancies) for each group, registered at KCR for the same period as controls. Cancer of the lung ranked the most frequent malignancy in men in Karachi in the entire 1995-2002 period, though it did not feature amongst the first 10 malignancies in the females. In the 1995-1997 period, the ASR per 100,000 population for cancer of the lung was 21.4 and 2.9 in males (M) and females (F) respectively. The mean age of the patients was 60.4 years (95% CI, 59.1-61.7) M and 53.7 years (95% CI 48.9-58.5) F. In the 1998-2002 period the incidence rate increased to 25.5 per 100,000 (M) and 4.2 per 100,000 (F). Thus between 1995 and 2002, the incidence of lung cancer registered a 19% increase in men and almost 100% in women. The component of adenocarcinoma in females remained stable during 8 years, but increased 55% in males. Histologic confirmation was 80%; majority of cancer cases presented as grade 3 and grade 4 lesions (62.3%), and were discovered at advanced stages (stage III 35.7%; stage IV 55.8%). The odds ratio (OR) in men was 4.5 (95% CI 3.7; 5.4). The risk of developing lung cancer increased with age, the highest risk being observed in the 65+ age group. A marginally higher risk was observed in the higher socio-economic categories for men and in the lower socio-economic categories for women. A higher risk was also observed for men who were residing along the coastal belt, and for ethnicities belonging to Southern Pakistan (Sindhi and Mohajir) residing in Karachi South. In conclusion, Pakistan at present falls into a low risk lung cancer region in females and a moderate risk region for males and the highest registered increase between 1995 and 2002 was observed in the older age groups (65+). It is however a cause of concern that the overall lung cancer incidence rates continue to rise. The age specific rates though stable in the younger age groups (35-49 years), are at present equivalent to contemporary rates in high- risk countries. These rates correspond with the trends of smoking prevalence in the younger age groups in the last 2 decades. Published studies have given alerts to increase in the smoking habits of the present day youngsters and with an expanding population the country can expect a substantial increase in lung cancer. This threat can only be averted by implementation of stringent anti-tobacco rules and health education; prohibition of smoking in educational institutions at all levels and a ban on the sale of cigarettes to minors.