An Assessment of Improvement in Reliability and Completeness of Mumbai Cancer Registry Data from 1964-1997

Abstract

The Mumbai Cancer Registry was established in 1964 with the aim of obtaining reliable morbidity and mortality data from precisely defined urban population. It was first and only such registry for merely two decades functioning in the country. Up to now more than 200,000 cancer cases are registered and with over 100,000 cancer deaths are recorded in data files. For studying improvements in the Mumbai Cancer Registry data, the data published in consecutive seven volumes (Vol.-II to Vol.-VIII) of "Cancer Incidence of Five Continents published by International Agency on Research on Cancer", Lyon, France have been used. For studying completeness of the data, the indicators 'Proportion of Deaths in Period'; 'Proportion of Death Certificates only' and stability of age incidence rates have been utilized. The indicators 'Proportion of cases registered on histological verification', 'The proportion of cases where age is not known', 'The flattening of age incidence curve' and 'Proportion of other and unspecified neoplasms can throw some light on the quality of data collected by the registry. There has been notable improvement in percentages of histological verification cases and substantial decrease in the proportion of death certificate alone cases in both the sexes over a period of time. Mortality Incidence ratio remained stable over a period of time in both the sexes. The proportion of cases where age is not known never exceeded 0.020% in either sex, for any site, for any period. The proportion of cases registered as other and unspecified sites, initially was around 8 to 9% then it has been dropped down to 5%. The crude incidence rates for all sites together are stable throughout the period of observation in both the sexes while age adjusted incidence rates show declining trend in both the sexes. There is no change in the pattern of age-specific incidence curves over a period of time in both the sexes. On examining various indices of reliability and completeness of Mumbai cancer registry data it can be concluded that, the data collected by this registry is quiet complete and reliable. While applying various checks for validity for a period from 1964-66 to 1993-97, it indicates that there is quiet improvement in almost all indices over a period of time in Mumbai cancer registry data.