Stiffening of jaw muscles is a warning signal in regular smokers and those wont to popping little packs of gutka into their mouths.
Oral submucous fibrosis is the pre-cancerous stage and 10 percent of these can develop into oral cancer, says a top expert.
What is worrying is that smoking is on the rise in India, especially among the young, as is the rise in the consumption of bidis, pan masala and khaini or chewing tobacco. This trend is all the more so in eastern Uttar Pradesh and Bihar.
Stopping tobacco consumption in India would help prevent 65 percent of cancers in India, including 15 percent among women, said Lalit Kumar, professor of medical oncology at the Institute Rotary Cancer Hospital of the All India Institute of Medical Sciences (AIIMS).
"Tobacco consumption can sometimes cause submucous fibrosis, where the jaw muscles get fibrosed and the person can't work the jaw muscles properly. The individual has to take liquids. This is the pre-cancerous stage," Lalir Kumar told IANS.
Ten percent of such cases develop into full-blown oral cancer, where even surgery can't help, he added.
"The mucus membranes on the insides of both cheeks get affected by cancer; so there is no scope for surgery. How does one replace them? It is very difficult," said Kumar.
Oral cancer cases are seen largely in southern India, especially Kerala, where chewing betel nut or supari is common.
The premier institute sees around 10-12 cases of oral cancer a year, the doctor added.
Other forms of cancer that tobacco consumption can lead to are of the head and neck, cheek, tongue, the lips and even the posterior part of the tongue - or the oropharynx, he said.
Keeping a cigarette or bidi dangling from the mouth may look hip, but those prone to doing so could run the risk of getting lip cancer.
Tobacco consumption can even lead to cancer of the voice box or larynx, which would lead to removing the larynx, Lalit Kumar said.
He said cancer due to tobacco consumption can even travel down to the food pipe, or oesophagus, and also cause stomach cancer.
Of late, cancer of the head and neck and foodpipe has seen a rise.
"For more than 50 percent of all cancers smoking is a major contributor," said Lalit Kumar, adding that smoking is also on the rise among women in India.
Lung cancer is on the rise among women in India as well as cases of cancer of the head and neck. "A lot of women in villages smoke bidis and chew tobacco and khaini. It is very popular in Bihar and eastern UP. Tobacco contributes to 15 percent of cancer among women," said the expert.
"If we stop tobacco, 50 percent of cancer among men and 15 percent among women can be stopped," said Lalit Kumar.
In India the incidence of cancer due to tobacco consumption is higher. "In the US, smoking is coming down. They have a rule that people can't smoke in public places and they stick to it."
"In India, under former health minister A. Ramadoss we had legislation to impose a fine for smoking in public places. There has to be social awareness about the dangers of smoking. It has to come from schools and colleges and has to be part of the day-to-day activities. There should be legislation against smoking and it should be followed up," said the expert.
Lalit Kumar dismissed the touted benefits of smokeless tobacco, saying "it is equally bad, there is no difference".
Smoking chillums and hookahs, which is a growing fad in plush bars, is bad too, according to Lalit Kumar.
"It is equally bad. In villages, people smoke chillums and hookahs and cancer is prevalent among them," he said.
"There is not a single thing good about tobacco."
Nearly 90-95 percent of cancer cases in India are related to environment and lifestyle, Lalit Kumar said.
The global burden of cancer includes 12.7 million newly diagnosed cases per year, of which more than half occur in less developed regions of the world. Cancers now account for more than 15 percent of the world's annual deaths (over 7.5 million per year), and that number is rising, especially in less affluent countries.
According to data, the annual incidence of cancer in India per 100,000 people has seen a rise over the years. From 68.6 per 100,000 in 1984, it rose to 78 in 2005 and is slated to soon reach 90 per 100,000 people.
Annual deaths due to cancer have seen a rise - from 266,600 in 1984 to 449,000 in 2005 and is slated to reach 600,000 in 2020.