Latest data shows that cancer is rising sharply in India. It's time we understood the intriguing facts from cancer registries to frame a more nuanced control strategy
Diagnose the discord
Sitting in a surgical oncologist’s cabin, Shyam Babu (name changed) curses the day he gave in to his old habit of chewing tobacco and consuming alcohol. Just six years ago, the 63-year-old Delhi-based textile businessman had successfully defeated mouth cancer. He now suffers a relapse of the disease. “I am talking with a lot of pain and great difficulty,” says Babu, as he shows marks around his neck caused by radiotherapy.
Tobacco-related cancers, which include the cancer of lip, tongue, mouth, oropharynx, hypopharynx, pharynx, oesophagus, larynx, lung and urinary bladder, have emerged as the biggest cancer group in the country. Though easily preventable, they account for about 30 per cent of the country’s total cancer load. In the Northeast alone, tobacco is responsible for 60 per cent of the cancer cases (see ‘Life in cancer capital’).
This is the finding of the consolidated reports of cancer registries, released by the Indian Council of Medical Research (ICMR) in May. ICMR started setting up cancer registries—27 population-based and 29 hospital-based—in the 1980s under its National Cancer Registry Programme (NCRP). The population-based registries cover less than 10 per cent of the country’s population. Yet, NCRP claims that they reflect the cancer profile of the country fairly well owing to representation of registries from different parts of the country. Based on complex statistical analysis of these divergent data, the reports make another startling observation: cancer cases are rising at a rate much higher than predicted. In 2013, ICMR said there would be 1.32 million new cancer patients in the country by 2020. Based on the latest data, ICMR has now revised its projections to 1.73 million new cancer cases by 2020—this is a 30 per cent jump from its earlier estimate.
Crude rate data shows that Aizawl district has the highest number of cancer cases among both men and women. Thiruvananthapuram, Kollam, Kamrup Urban, Chennai and Mizoram registries have also recorded high number of cancer cases.
The data shows a significant rise in the incidence rates of lung, colon, rectum and prostate cancers among men. Among women, lungs, breast, ovary and corpus uteri cancers are becoming more common (see ‘Mapping the spread’).
Breast cancer, for instance, is the leading form of cancer at 19 of the 27 cancer registries. With 150,000 new cases, breast cancer is projected to become the most common form of the disease in 2016. With 114,000 and 100,000 new cases, lung and cervical cancers are next in the list.
The data also indicates that northeastern states have high incidence rate of cancers. To measure the incidence rate, researchers use a statistical term, age-adjusted rate (AAR). Since cancer incidence is high among the elderly population, AAR makes the incidence rates comparable among different age groups. According to the ICMR reports, Aizawl has the highest AAR for all types of cancer among men. Papumpare in Arunachal Pradesh has the highest AAR for all cancers among women.
The north-eastern states, however, report low incidences of childhood cancer compared to several metropolitan cities. With an AAR of 235.3 per 1 million boys and 152.3 per 1 million girls, Delhi tops the chart in childhood cancer cases. It is followed by Chennai where cases of cancer are high among boys and Thiruvananthapuram where cancer cases are high among girls.
Soumya Swaminathan, director general of ICMR, says the higher numbers reflect improving cancer detection rates, age-related cancers due to increasing life expectancy and higher exposure to cancer-related risk factors.
The reports, however, do not explain why the incidence rate of same cancer is different in different parts of the country. For instance, the annual percentage change in uterine cancer cases in Bengaluru is the highest (5.5), while that in Delhi is 3.6. It does not even explain why the same kind of diet causes two different types of cancer. For example, the diet of people in Mizoram and Nagaland is rich in fermented food and smoked meat and fish. Consumption of tobacco and chewing betel nut is also high among these communities. But while cancer of stomach is high among Mizo men and women, Nagaland registry records a high AAR for cancer of the nasopharynx (which extends from the base of skull to the upper surface of the soft palate).
“This is intriguing and needs to be studied properly,” says Eric Zomawia, principal investigator at Mizoram cancer registry. The data also needs to be analysed in context of new cancer risk factors, such as air pollution and pesticides.
“We need specific studies in our country to understand the factors that contribute to cancer occurrence here,” says A Nandakumar, director-in-charge, National Centre for Disease Informatics & Research, National Cancer Registry Programme in Bengaluru (see ‘Region-specific, organ-specific research needed’).
“The government needs to be a key promoter and supporter of research by funding such initiatives as well as identifying priority areas,” says Arun Kumar Goel, surgical oncologist at Max Super Speciality Hospital in Ghaziabad, Uttar Pradesh, who calls India a “gold mine” for epidemiological studies and specific research on various cancers.
So far, we have depended on Western research for planning treatment, screening and prevention strategies for cancer, says Goel. But it’s time to question these strategies.
For breast cancer, the well-accepted reasons are delayed motherhood, having fewer babies and the practice of avoiding breastfeeding. But is this true for India?
`Region-specific, organ-specific research needed'
These reports peg breast cancer as the number one cancer in India, followed by lung cancer. But the situation is not same everywhere. In the Northeast, cancers of oesophagus, hypopharyngeal (throat and upper throat) and cervix pose a serious threat. In Mizoram's Aizwal district, oesophagus and stomach cancers are increasing at an alarming rate. In Delhi, cases of prostate cancer are increasing by 3-4 per cent every year. Whereas in southern Indian states, particularly in Bengaluru and Chennai, stomach cancer is among the top five types of cancer that require attention. Similarly, cases of colorectal cancers are going up in all urban cities, particularly among men.
This difference is due to different lifestyles and eating habits of people. The major reason behind cancer in the Northeast could be high consumption of smoked meat and tobacco. We interacted with 200 high school girls in Meghalaya and found that almost 95 per cent of them were smokers. The high incidence of stomach cancer in Bengaluru and Chennai could be spicy food by predominantly rice-eating population. Increasing cases of colorectal cancer in urban areas can be linked to processed food. But we need studies to determine the causes.
It is essential that we have a region-specific and organ-specific approach towards control and prevention of cancer. This exciting profile of India opens up an opportunity for epidemiological studies. But lack of funds to expand the registries to more states or conduct specific studies is a constraint.
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