The importance of epidemiological studies in a developing country such as India cannot be stressed enough. Over the past decade or so, rapid urbanization and lifestyle have led to a new set of disease trends in India that include a large number of non-communicable diseases that includes Cancer, Diabetes, and Cardiovascular Diseases. There is a critical need to build essential health policies, and this can be achieved with a renewed focus on epidemiological studies in various disease areas and regions in the country as highlighted by Dr. Manigreeva Krishnatreya in this interview.
Please elaborate on the importance of epidemiological studies in developing countries both in the context of cancer and in the context of incidence in the North-East region of India.
Epidemiology is the study of the distribution and determinants of health-related states or events in specified populations, and the application of this study to control the health problem. The prime objective in epidemiological studies of cancer is to find out the factors affecting cancer, to infer possible trends and causes.
Epidemiological study on cancers can be broadly categorized into three research groups, namely: Descriptive, Analytical, and Clinical Epidemiological. So far, cancer prevention studies in North-East India has been the domain for basic cancer researchers with limited epidemiological perspective. However, the combined role of physician oncologists, basic researchers, and cancer epidemiologists for epidemiological studies has so far remained as an unmet need in this region. At this juncture, the high incidence of certain types of cancer in North-East India have remained unexplained and it cannot be solely explained by the established risk factors as outlined in the scientific literature. Similarly, when it comes to cancer survival, it is not reasonable to apply current guidelines of cancer treatment for the cancer population of North-East India to achieve high survival estimates like that of the rest of India. This is due to differences in incidence, genetic make-up and tumor biology, socioeconomic factors, and availability of resources in the region. In this regard, the National Cancer Grid is formulating specific nationwide guidelines for cancer management. The right way to manage the rising cancer burden in North-East India is by proactive participation in cancer research by all the stakeholders.
While considering HBCR versus PBCR – what kind of information does each provide and how are they used?
Hospital-based Cancer Registry (HBCR) reports mainly on the Pattern of Care and Survival of patients attending a hospital where the registry is functioning. In contrast, Population-based Cancer Registry (PBCR) provides information on incidence, prevalence, the mortality of cancer in a specified population, and can further provide information on population-based cancer survival. For estimating the population-based cancer survival by a PBCR, we require data on the life expectancy at different age groups or so-called “life tables” and information on survival of cancer patients of the select geographical area. Population based cancer survival is the most unbiased estimate for measuring effectiveness of existing cancer control efforts by the Government. In India, HBCRs and PBCRs are funded by the Indian Council of Medical Research and function under the network of National Cancer Registry Programme (NCRP) of India. The NCRP is located at the office of the National Center for Disease Informatics and Research in Bengaluru. The network of HBCR and PBCR submit respective registry data to the NCRP. The NCRP then publishes the consolidated report of PBCR and HBCR, which then decides the priority areas for cancer research in the country.
Do you feel that we are doing enough epidemiological studies in India?
Most of the major population-based epidemiological studies on cancer in India have been region-specific. For example, epidemiological research at Tata Memorial Center in Mumbai speaks for the western region or Maharashtra in particular, and cancer research at WIA in Chennai for the southern part of the country. It will be an excellent idea if all major cancer centers of the country join hands to participate in epidemiological studies on various common cancers that is nationally represented.
What factors contribute to insufficient epidemiological studies in India?
The factors that contribute to insufficient studies are many. To begin with, lack of facilities for carrying out comprehensive epidemiological analysis is one reason. Next is the lack of awareness about the importance of epidemiological studies at the policy making level. The priority set for cancer control in resource constrained countries like India has been in making investments for its diagnosis and treatment, rather than looking for molecular biomarkers or genetic polymorphisms, and thereafter correlation with lifestyle and environment as an example. Another reason is a dearth of professionally qualified epidemiologists who are willing to contribute their expertise solely in cancer control and prevention by means of epidemiological studies.
Who is the consumer of data derived from epidemiological studies?
The consumer of data derived from epidemiological studies are doctors, practicing oncologists, public health specialists, and most importantly, the Ministry of Health and Family Welfare of Government of India for its flagship cancer control programme. The cancer control program is now merged with National Programme for Prevention and Control of Cancer, Diabetes, Cardiovascular Diseases and Stroke.
What actions are being taken regarding awareness of eating habits/ tobacco usage etc. in the North-East India to reduce the burden of cancer?
It is worth mentioning that, as per the latest report of Global Adult Tobacco Survey, there has been 9% increase in tobacco consumption in the state of Assam, whereas, nationally there is 6% decline in tobacco consumption.
In this regard, State Tobacco Control Cell, Voluntary Health Organization, and many like-minded NGOs are working closely with Dr. B. Borooah Cancer Institute, Guwahati to mitigate the menace of tobacco consumption in the State of Assam. The Education Department of the Government of Assam is actively working to ensure that Government-run and privately run schools are made tobacco free. It is well understood that, early intervention to prevent children from the addiction of tobacco is the sole way to curb its menace in our society. Regarding food habits, some molecular epidemiological studies have demonstrated that consumption of freshwater fish, which is a very common food practice, and locally used “Kala Khar,” a food item made of dried banana leaves are risk factors for gall bladder and esophagus cancers, respectively. Similarly, consumption of smoked meat and fish increases the risk of nasopharyngeal cancer in both men and women. Moreover, high prevalence of tobacco consumption by the people of the region accentuates the cancer risk in the population of the North East . Additionally, now we are also looking at heavy metals as a potential carcinogen for causation of gall bladder cancer. The study is presently ongoing with the Public Health Foundation of India as the coordinating agency. The potable groundwater in many parts of the State of Assam are infested with heavy metals like Arsenic, Cadmium, etc. beyond its permissible limit for human consumption.
Have epidemiological studies been able to shed light on higher incidence of breast cancer in younger women?
Yes, epidemiological studies have been able to shed light on the higher incidence of breast cancer in younger women in North-East India. Furthermore, hospital based clinical studies have shown higher proportion of triple-negative breast cancer among women of the region compared to the rest of country. Now, the focus should be on identifying women at risk in our population for harboring triple-negative breast cancer.
Has there been a significant change in diet or lifestyle for the people of the NE over the last two decades?
Yes, there has been a significant change in diet and lifestyle of people of the North East India over the last two decades, which will be same for the whole of country as well. A rise in sedentary lifestyle along with the, increase in the consumption of high fatty food and low fibre diet has come at the expense of consuming fast food in the ever-growing multi-national food joints. Rapid urbanization has also contributed to change in lifestyle and dietary practices. In 1980s and early 1990s, people residing in major towns and cities of the North-East India were following dietary habits and lifestyle of the countryside people. Now things have changed, for the worse. Sad, but true!
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