Investigation of a cancer cluster in an industrial area of North India

Abstract

Introduction: Cancer clusters always get a lot of attention in the media. It is an aggregation of relatively unexpected high number of cancer cases. People become concerned that a cancer cluster exists in a certain community and that it is caused by some type of carcinogen that is being released into the environment. We investigated a similar concern regarding suspected clustering of cancer cases in an industrial area of a district in North India. Materials and Methods: A retrospective cohort study was carried out from March 1, 2016, to May 31, 2016 taking the whole study area population as exposed. House-to-house search of cancer cases was undertaken retrospectively from the year 2011 onward. The total population of the cohort (denominator) was taken from the census of India 2011 data. Age-adjusted standardized rates were calculated. Results: A total of 53 cancer patients were identified. A maximum number of cases were of the lip and oropharynx (15.1%), followed by the lung (13.2%) and esophagus. The yearly incidence of cancer for both sexes ranged from 87.2 to 90.9/lakh population. The 5-year period prevalence for both sexes was 207.4/lakh population. Conclusion: This panic occurred due to a list of cancer cases given to the health department by the residents and public representatives of the area. As these were just figures without a denominator, it gave a false impression of a high number of cancer cases. However, on conducting this study, we found the age-adjusted cancer incidence to be similar or even lower than the Global Cancer Incidence, Mortality and Prevalence, and Indian Council for Medical Research figures for India. Hence, we ruled out a true cancer cluster.