WOMEN MORE VULNERABLE: According to Dr Ang Mei Kim, 70 per cent of ‘never-smokers’ with lung cancer are women.
MORE women who have never smoked are being diagnosed with advanced stages of lung cancer.
Madam Christine Chen* started coughing on and off for four weeks, and was initially given antibiotics by her doctor to treat what he suspected was a lung infection. However, despite taking the antibiotics, she continued to cough, and in fact started feeling slight breathlessness when walking or exercising.
She had no reason to suspect she had lung cancer. after all, the 45-year-old was medically fit and had no family history of cancer. She worked in a primary school, never smoked, and neither did anyone in her family, so she had no exposure to second-hand smoke either.
Mdm Chen went back to her doctor and underwent a chest X-ray which showed multiple spots in both lungs. Subsequently, a CT scan was done at a hospital and it picked up not only bilateral lung masses but also enlarged lymph nodes and fluid in her lungs. A bronchoscopy and lung biopsy confirmed that she had Stage 4 lung cancer and that the cancer had spread to both lungs, the lining (pleura) of her lungs, and her lymph nodes.
Mdm Chen is not the only patient who has never smoked, yet has fallen prey to lung cancer. These “never-smokers” – as they are referred to in the medical field – are being hit by the disease, and hit hard too.
A study by the National Cancer Centre Singapore (NCCS) found that three in 10 lung cancer patients here are never-smokers and the incidence is rising, said Dr Ang Mei Kim, Consultant, Department of Medical Oncology, NCCS.
More than half the never-smokers seen at NCCS are usually diagnosed with advanced stage (Stage 3 or 4) lung cancer. “There are few tell-tale signs. It sneaks up on them to deal a heavy blow. Symptoms at the time of diagnosis are cough, blood in the phlegm, chest pain, breathlessness and weight loss,” said Dr Ang. She said women seem more vulnerable than men, as 70 per cent of never-smokers with lung cancer here are women.
The statistic is even more glaring when compared globally, where it appears that Asian female non-smokers are more vulnerable to lung cancer than their Western counterparts.
“Less than 4 per cent of Chinese women in Singapore smoke, yet, Singapore has a higher lung cancer rate among women (21.3 cases per 100,000 females) compared to other countries like Germany and Italy, where one in five women smoke,” said Dr Ang.
Examining risk factors
Exposure to second-hand smoke at home or at the workplace – one of the main causes of lung cancer in never-smokers – increases the risk by 25 per cent.
Another risk factor is environmental pollutants, particularly radon. Studies in Chinese populations show that burning coal and biomass, particularly in poorly ventilated areas for cooking and heating, may also increase the risk.
“A large proportion of lung cancers in never-smokers cannot definitely be associated with any established environmental risk factor. It is also thought that certain genes, or changes that occur in the genes, may affect a person’s susceptibility to these carcinogens and to developing lung cancer. This is an area of current intense research,” said Dr Ang.
Not the same type of cancer
Studies done around the world and in Singapore show, in general, that never-smokers who develop lung cancer, have a higher survival rate than current smokers and former smokers. This is most likely due to differences in the types of lung cancer that develop, and the distinct genetic differences that exist between never-smokers and smokers with lung cancer.
Dr Ang explained that the two main types of lung cancer are small cell lung cancer and non-small cell lung cancer (NSCLC).
The diagnosis is based on microscopic examination of a lung biopsy. Small cell lung cancer makes up 10 per cent of all lung cancers, and grows more rapidly and spreads earlier to other organs than NSCLC. It is also found almost exclusively in smokers. Survival outcomes are poor.
On the other hand, NSCLC grows more slowly than small cell lung cancer and tends to be confined to the lung for a longer period of time, and the chance of survival is generally higher than for small cell lung cancer.
Cancers, in general, have many gene changes or mutations, which promote the growth and spread of the cancer cells in the body.
Certain types of gene changes, when found to be present, can be targeted with specific drugs (targeted therapy). When these drugs are given to patients with advanced stage lung cancer, they may block the growth and spread of cancer cells more effectively than chemotherapy. Dr Ang said: “Studies show that never-smokers have different genetic changes in their lung cancer cells compared to smokers, which may make their lung cancers more responsive to these targeted treatments, compared to smokers with lung cancer, and leading to better survival outcomes.”
Smokers and never-smokers undergo similar treatments, depending on the type of lung cancer and what stage of cancer they have.
In Stage 1 and 2 NSCLC, surgery to remove the cancer is usually performed. Chemotherapy may be used after the operation to lower the risk of relapse and improve survival rates. In Stage 3 NSCLC, a combination of chemotherapy and radiotherapy is usually used, while in Stage 4 when cancer cells have spread to other parts of the body, chemotherapy and targeted treatments may be used.
That said, prevention is still better than cure, said Dr Ang. “While lung cancer can strike anyone, there are things that never-smokers can do to better protect themselves. First, if you have never smoked, don’t start. Second, avoid regular, long-term exposure to smoke. Third, while not actually proven to lower the risk of cancer or prevent it, many studies show that in general, a healthy diet and lifestyle, as well as exercise, are associated with lower rates of cancer.”
*Patient description is based on a typical patient profile
This story was first published in Singapore Health, Nov/Dec 2013.