Cancer is a global leading cause of deaths amongst adults. The International Agency for Research on Cancer estimated a death toll of 7,84,821 people from cancer in India in 2018 alone, amounting to 8 percent of global cancer deaths and 6 percent of deaths from all causes in India [1]. Additionally, dying from cancer before the age of 75 years is 7.3 percent among men and 6.3 percent among women. The absolute numbers are expected to increase in future in the purview of the increasing population and life expectancy of India. Increases in the age-specific cancer risks of tobacco use will propel the rates of cancer deaths also, by increasing the incidence of quite a few types of cancer [2].
Cancer is a prominent cause of morbidity as well as mortality in many developed and developing countries. Most of the low-and-middle-income countries (LMICs), including India, lack an organized and functional cancer care system [3]. Cancer diagnosis and subsequent treatment, in combination with other acceptable services, can lead to catastrophic health expenditures, pushing entire families below the poverty line [4-6].
Population ageing is often considered to be the main driver of an increased cancer incidence and the death rates and increased costs incurred thereafter [7]. The picture is more complex than that, though. High-income countries (HICs) have age-standardized cancer mortality decreasing across all the age-groups, except the groups with the population aged more than 70 years, in which more than half of the cancer deaths occur. No evidence exists regarding such decrease in the age-standardized cancer mortality rates in India, in spite of low population coverage in data collection. Most of the deaths attributable to cancer also occur in the age-groups with the population less than 70 years of age [8]. Indian population’s relatively younger age structure is a little different from other HICs, which may partly contribute to these differences.
Other factors, which may be playing an essential role in the higher rates of cancer deaths in India as compared to other wealthy countries, may be the prevalence of infections and unique local patterns of tobacco consumption within regions in India. Inaccessibility and non-availability of screening and early-stage cancer diagnostic services also seem to explain the paradox of low incidence rates and higher age-specific death rates in India. Improvements in the living standards and Human Development Index (HDI) rankings have traditionally been associated with increase in the occurrence of, e.g., cancers related to sex hormone exposure and those related to reduced average family size
[
6]. The gains acquired owing to the economic and social development, dwarf the associated costs incurred due to the increased cancer care.
The GLOBOCAN project has forecasted India’s cancer burden in 2035 (approximately 1.7 million new cases) to be almost double the amount of that in 2012 (slightly above 1 million). Consequently, the number of cancer deaths will also escalate from around 680,000 to 1.2 million in the same period8. The magnitude of the actual increase in cancer-related mortality and disability will be based on the investment decisions in health care, cancer research, public knowledge of risk factors in the future as well as other developmental and social changes affecting disease incidence and outcomes.
There is a dearth of comprehensive cancer incidence and mortality data for India. Only the National Cancer Registry Programme provides some population-based estimates from the extant 28 cancer registries located across India [9], based on which GLOBOCAN estimated the India-level statistics. The limitations, e.g., of over-representation of the urban and south-Indian population and under-representation of the rest of the country as well as of cancer deaths among the older ages still remain. Nevertheless, these estimates are the most reliable for planning and management of cancer across India. According to GLOBOCAN, 14 million new cancer cases were diagnosed globally, and more than 8 million deaths attributable to cancer occurred in 2012 alone. Around a million of these diagnosed cases and 700,000 of the deaths occurred in India, home to approximately 17 percent of the world population [8].
Immigrant Indian populations in the USA and the UK exhibit growing convergence of their cancer experiences with their adjacent communities [10,11]. The Indian burden of disease is distinctly different from its post-industrial counterparts. The more common forms of cancer among Indian men are tobacco-related. Among women in India, the incidence of breast and cervical cancer is the highest among all the forms of cancer [3]. Deaths due to cervical cancer are the second most common cause, even when both the sexes are combined. Ratios of cancer incidence to mortality vary significantly among economically developed and developing countries. India, being no exception to this pattern, is affected by causal variations, stage at diagnosis, and the availability and use of cancer treatments. The cancer mortality is high at a rate of 68 percent of the annual incidence in India, underlining the fact that less than 30 percent of those diagnosed with cancer survive five years or longer after the diagnosis. Data limitations may cause the actual survival rates to be even lower. On the contrary, in North America and Western Europe, the five-year survival rates for all cancers are approximately 60 percent. Delayed diagnoses, incorrect or sub-optimum treatment (including inability of patients to complete or even access apt therapies), may be the principal factors resulting in poor cancer survival in India [12,13].
The burden of disease due to cancer in India varies greatly among regions [10]. Cancer mortality and incidence is predominantly higher in the more affluent states, though mortality rates are constituted substantially by cancer deaths in rural areas too, owing to scarce or non-availability of cancer treatment facilities. Individuals from the lower socio-economic strata are at a higher age-specific mortality risk as compared to their better-off counterparts [14]. Even though cancer causes around 10 percent of all deaths in India annually, the absolute numbers wreak havoc on the public health sector, necessitating better cancer management, widespread awareness and a strong framework for improved care. One way to improve assessments of the national burden would entail making cancer a reported phenomenon, for which establishment of new and improved registries would be a viable solution. Results from thoroughly conducted sample surveys like the Million Deaths Study could also put the issues like regional variations into sharp perspective, thereby aiding in improvement of overall cancer policy and its care. The increased number of new cases of cancer by 2035 are primarily because of an ageing population. In spite of the decrease in age-specific incidence and mortality, increased survival rates, whenever achieved, will propel the overall prevalence of cancer to still increase.
A culturally diverse country like India has huge underlying regional and sectoral (urban-rural) variations, which extend even up to lifestyles and variations in age-specific death rates [15]. So, the assessment of the geographical and social distribution is essential to frame cancer control programmes and specifically target those groups, which require attention, to incite further research into the causes of cancer. Cancer is unequally distributed in societies, people hailing from particular socio-economic groups maybe burdened disproportionately with the disease. A number of socio-demographic (age, social group), behavioural (tobacco consumption) and health-related (body mass index) indicators have been proposed to be explaining this gradient in the occurrence of cancer. This study aims to assess the social and regional variations and the contributions of the selected cancer indicators in the country.