NAZIR AHMAD DAR
Cancer is undoubtedly a serious health concern worldwide. Based on available data and estimates from five continents and 187 countries (including India), International Agency for Research on Cancer (IARC/WHO, Globocan, 2020) reported 20 million incident cancer cases and about 10 million cancer deaths in 2020. In India, the number was 13 lac in 2020 and by 2025 it may reach 15 lac (an estimated 12% increase). Tobacco-related and gastrointestinal cancers constitute 27% and 20% of cases, respectively, in India. The highest rates were in Northeastern states and correspond to a high prevalence of tobacco consumption in the region. The figures are from population-based cancer registries (PBCR) and hospital-based cancer registries (HBCR) including HBCR from SKIMS. The data available and analysed by national agencies is up to 2018 including data from SKIMS.
SKIMS registered cancer cases exceeding 5000 patients. In men and women combined, lung cancer is leading cancer detected in the valley. This is followed by cancer of the stomach, breast and food pipe. However, cancers of the digestive tract, if put together, are the most common cancers in Kashmir valley.
Due to substantial progress made in the early detection, rapid diagnosis, and management of cancer patients, there has been a significant increase in the survival and quality of life of survivors. This is especially true about North America and Europe. Roughly, cure rates have improved by one per cent each year in the last two decades in these regions. However, developing nations have bigger challenges owing to a lack of cancer awareness, lack of adequate resources, and inadequate health spending to deal with the increasing incidence of cancer. A lot more needs to be done on all fronts. There is a huge disparity in cancer prognosis between developing and developed countries. Cure rates for common cancers such as breast cancer exceed 80% in developed countries whereas the rates are dismal in poor countries. In esophageal squamous cell carcinoma, patient survival for 5 years is more than 20% in the developed world and <5% in settings like ours. It is high time to further strengthen and expand the efforts being put in place by all our government agencies, clinicians and scientists.
Recent articles published in Greater Kashmir (November 9, 2022, Jan 17 and 18, 2023) and on social media, prompted me to put forth the scientific aspects of the cancer scenario in Kashmir. The articles, including one which has used reliable data from the Ministry of Health, without ambiguity, has highlighted the figures and sensitized everyone including administration, clinicians, researchers and policymakers. The response should also manifest into more efforts by all stakeholders to carve out immediate and long-term remedies. The triangular collaboration involving scientists, clinicians and administration is inevitable.
Fifty-one thousand cancer cases in 4 years (2019-2022) in Jammu and Kashmir is an extraordinary number which no way can be ignored. However, the data needs to be presented in a scientific way to achieve the main objectives of collecting such data. The data must help in knowing patterns and trends of cancers over time, guide planning and evaluation of cancer control efforts and help prioritize health resource allocations. I want to discuss two important concerns about the cancer numbers and the factors that contribute to their rise (if at all) in Kashmir. I present my view on the basis of scientific experience and understanding of the subject over the years and available literature.
1. Incidence: The geographical distribution of cancers is not uniform across the globe. There is variation in the incidence of cancers across continents, countries and even within a country. The high incidence of cancer in any population, most likely, reflects the presence of risk factors for that cancer in the population. For example, in the developed world, the main cancer risk is attributed to tobacco and alcohol consumption while in the developing world the ‘low socioeconomic status’ is among the main risk factors.
To know the rise or decline of a cancer burden in the population we need to have incidence or prevalence. The number of total live cancer patients in a population at a particular point in time gives us the prevalence of cancer. While incidence refers to new cases diagnosed with cancer in the population in a given time. It is expressed as a crude incidence rate or age-standardized rate (ASR). The crude rate is obtained by dividing the incident cases by population size (usually the crude rate is calculated per 100,000 people of population per year). The figures in these articles were not crude incidence rates to the best of my knowledge.
If we need to compare incident rates in two or more periods; or two or more populations, the rate needs to be ASR. Age has an important role in cancer incidence as the risk for all cancers increases with age. Hence, to give a scientific representation of our cancer registrations, we need to put it into a crude rate or ASR, that can explain the rise or even decline of any cancer. None of the reports used the correct incidence terms.
For incidence or prevalence calculations, ideally, data from PBCR is used. PBCR registers all new cases in a defined population. As mentioned above PBCR besides its many important uses, helps us to know the epidemiology, the cancer patterns in our population and tract cancer trends over time. We need to hold till a clear picture is revealed from PBCR in SKIMS, particularly in terms of patterns and trends of cancers in Kashmir.
In absence of the data from PBCR, the data used from Kashmir is from the HBCR at SKIMS. HBCR gives us some idea of cases recorded in SKIMS. HBCRs ideally maintain data on all patients diagnosed and/or treated for cancers at a particular facility. The focus of the hospital-based cancer registry is on clinical care and hospital administration. The HBCR need to be linked to other HBCRs in UT. The data from all PBCR in UT needs to be integrated, analysed and then to be presented in the appropriate scientific syntaxes.
The population is increasing and our valley is no exception. Our population size has increased, on average, by more than a million in each of the last 3 decades, so an increase in cancer cases is expected. Further, the structure of the population is changing dramatically. Our country is in a healthy economic transition. Life expectancy has increased and the number of old aged people is increasing in all populations across the country. The number of Indians of 60 years or older, was 5% in 1950, 10% in 2016 and will be 19% in 2015. It means at present, there is more than 1 person in every 10 persons aged 60 years or older. The incidence of cancer overall climbs steadily as age increases. According to a NIH data, the estimated number of cases was 25, 350 and >1000 per 100,000 for age groups of >20, 45-50 and 60 and older, respectively. Hence, the cancer data, if put in terms of crude incidence rate or preferably in ASR only then we can know if cancer is really on the rise in Kashmir or UT. Further, the trend and patterns cannot be concluded on a few years’ data, it needs data to be watched over a couple of decades. The PBCR and HBCR at SKIMS will provide an answer to all our questions and concerns in the coming years. These important data treasures need to be made accessible to everyone, particularly epidemiologists and bio-statisticians, who can give a better picture of the cancer patterns and incidence in Kashmir.
Risk factors: Another important aspect of cancer-related concerns in Kashmir is the temptation everyone gets to conclude about its aetiology or risk factors. The 10 most common cancers (lung, stomach, esophagus, breast, thyroid, colon, GE junction, NHL, rectum and ovary) cancers in Kashmir cannot be grouped. Although there can be a common factor to many cancers, (like smoking). The cancers are different from one another with different developmental processes and etiological root causes and treatment outcomes. It is an established factor, that transition to better economic conditions is associated with a lifestyle change.
This change usually results in a decrease in the incidence of some cancers but at the same time results in an increase in the risk of other cancers. The change is manifested in different parameters, including, in terms of an increase in BMI, an increase in a sedentary lifestyle from an active lifestyle and an increase in cumulative tobacco and alcohol use. However, studies need to be carried out to check the effect of these possible factors related to the transition in the economy in JK.
Each cancer is considered a different disease. We need to develop questionaries, test and validate them, build databases with appropriate softwares and conduct studies on big numbers (on a few 1000s) of participants with appropriate controls. Conditional logistic regression might be an appropriate statistical tool with confounding of all known risk factors of a cancer known/suspected in our or other repopulations, which can help us find risk factors of a cancer in Kashmir. We need to move to genetic studies also using next-generation sequencing (NGS) platforms. Candidate gene studies are discouraged in the current era of NGS. We need to find exposure markers from NGS studies that will augment epidemiological studies. NGS might help us to identify markers of treatment response and also to develop precision medicine. Unless we will not conduct quality studies to establish risk factors for each cancer, it will be too early to conclude anything. The suggestions based on observations about the risk factors need to be substantiated by appropriate studies. We have meagre well-conducted studies and most have limitations in terms of design or analysis or were carried out with some biases or lack adjustments for confounding in analysis. Further, the small sample size of previous studies restrains readers to reach any conclusion.
Quality studies are warranted with the least or no limitations in J&K to understand cancer aetiology and epidemiology. The studies are not easy and besides funding need a lot of effort among the collaborators. It is pertinent to mention that the most difficult part of epidemiological studies in our settings is to understand the role of food habits. We tried to assess for esophageal squamous cell carcinoma, but could not because of a quantification issue. Once epidemiology and risk factors are understood, next we can move to the public with interventions or suggestions to prevent cancer that can help us to attenuate the incidence of any cancer.
Note: Considering the vast spectrum of an audience of GK, the article is composed in a non-formal way, therefore, citing the sources of information and data was avoided.
Nazir Ahamad Dar, Department of Biochemistry, University of Kashmir