According to statistics provided by the Beijing Tumour Prevention and Treatment Research Office, in 2003, the rate of lung cancer among all types of cancers rose to 28 percent, as compared to 18 percent in 1977. That means there is one lung cancer patient among every four patients with a malignant tumor.

Wang Jie, director of the No 2 Internal Medicine Department of the Beijing Tumour Hospital, rates smoking as the number one reason leading to lung cancer.

According to the doctor, the international medical field has linked smoking with cancer since the 1930s. But people completely neglected the discovery until the 1990s. Today, among all cancers, lung cancer ranks No 1 for men in both incidence and death rate. Although it ranks number two among all types of cancer in incidence for women, it is also the most deadly among all cancers for women.

While most men with lung cancer smoke, most women develop lung cancer because of second-hand smoke. It is said the second-hand smoke contains more incompletely burnt matter, which in fact contains more cancer-causing substances. Therefore, even if you don't smoke, those smoking around you are putting you at a higher risk than themselves for developing lung cancer.

Researches in the West compared a smoking group with a non-smoking group to further study the effects of second-hand smoke. If the chance of contracting lung cancer is 1 for the non-smoking group, then the chance for the smoking group who smoke from 1 to 20 cigarettes a day is 10.3. When the smoking group quit smoking, in the first two years the chance rose to 13.6, but from the 3rd year to the 6th year, the chance for those who quit fell to 8.4.

For those who smoke more than 21 cigarettes a day, the chance of developing lung cancer is 21.2. In the first two years they quit, their chances rose to 32.4. But after three years, that chance falls to 20.3.

As seen by the increased risk of developing lung cancer in the first two years after quitting, Wang says it is possible that a balance is broken in the body's system of resistance, therefore making the risk of developing lung cancer higher, albeit temporarily.

Although China has long advocated not smoking in public places, it is not uncommon to even see people smoking near no-smoking signs throughout the country. The government has not yet taken any harsh measures against smoking in public.

Apart from smoking, Wang believes kitchen smoke, environmental pollution and genetic factors can also become causes of lung cancer.

She suggests people keep away from smoking and smokers. Not smoking will benefit you and the people around you, including your family, she said.

Those who smoke regularly or have a family member who smokes or has lung cancer should go for a chest X-ray to make sure there is no sign of any respiratory difficulties.

(China Daily May 13, 2005)