Indian cancer riddle and eye-openers
|OUR SPECIAL CORRESPONDENT|
New Delhi, March 28: The risk of dying from cancer is nearly the same in rural and urban areas and the highest among the least educated, according to a study described as the first to provide nationally representative estimates of cancer deaths across India.
The study, by researchers at the University of Toronto, Canada, and collaborating Indian institutions, challenges a common perception that cancer in India is primarily a disease of urban and educated people, put at risk through new-age habits that lead to obesity and other lifestyle-related risks.
"Cancer is not a disease of the rich and the educated as it has sometimes been portrayed," said Prabhat Jha, the director of the Centre for Global Health Research. "The cancer death rate is two times higher in the least educated than in the highest educated adults."
The study, published today in the journal Lancet, suggests that tobacco-related cancers have contributed to over 40 per cent of cancer deaths in men and nearly 20 per cent of cancer deaths in women. It estimates that India had 560,000 cancer deaths during 2010.
The study has also confirmed that cancer is a major cause of adult deaths in India with more than 70 per cent of cancer deaths occurring among people between the ages of 30 and 69 years, or their productive years.
"Tobacco use may help explain the observed link between education and cancer deaths," Jha told The Telegraph. Tobacco consumption, particularly the habit of chewing tobacco, tends to decrease with higher levels of education.
Cancer epidemiologists say the study is the first to provide estimates of cancer deaths in rural and urban areas. All previous national data on cancer mortality was based on 24 registries run by the Indian Council of Medical Research but only two of these are in rural areas.
The findings are based on the Million-Death-Study — an effort to document the causes of child and adult deaths and their risk factors through the process of "verbal autopsies" — individual narratives obtained from household members of the circumstances of deaths.
The most common causes of cancer deaths in men were oral, stomach and lung cancers, while the cervical, breast and stomach cancers were the most common causes in women, according to the Million-Death-Study.
"There is a strong correlation between tobacco and low education levels," said Rajiv Dixit, professor of epidemiology and a member of the research team at the Tata Memorial Hospital, Mumbai, a collaborating institution in India. "While it is also possible that those who are better educated also get themselves diagnosed and treated early, we need to investigate how diet or nutrition might also change with education levels," Dixit said.
Jha said the similar cancer death rates in urban and rural areas was a "big surprise".
Cancer researchers in India had long assumed that incidence of cancer was twice higher in urban areas than in rural areas. But this was based on two rural registries.
The new study has shown that 95 men per 100,000 die from cancer in rural areas and 102 in urban areas. In women, the rates were 96 in rural areas and 91 in urban areas. "These figures may also reflect the absence of diagnostic facilities in rural areas," Dixit said.
The study has also shown strikingly sharp variations in cancer mortality across states — the highest in the Northeast and the lowest in the neighbouring states of Bihar, Odisha and Jharkhand.
"This is still a big puzzle — tobacco may explain only part of this pattern, but we really do not understand why the Northeast has a cancer mortality nearly four times higher than the rates in states like Bihar, Odisha and Jharkhand," Jha said.
"We need to understand whether diet or infections may be playing a role in the Northeast," Dixit said. "For instance, we observe high rates of stomach cancers in the Northeast, and there is high meat and pork consumption -- these could be contributing factors. But we also observe high rates of nasopharyngeal cancers in the Northeast. This cancer is sometimes associated with the Epstein Barr Virus -- we need to investigate the presence of this infectious agent there."