Understanding Lung Cancer and Treatment Breakthroughs
November 28 2005 Monday
Lung cancer develops when toxic substances such as tobacco smoke damage lung cells. The cells lose their ability to regulate growth, so they divide and multiply at an abnormal rate. In time, a mass of cells called a tumour develops. When this tumour turns malignant or cancerous, it starts to invade and destroys surrounding tissue.
Generally, cancers that develop in the lungs are divided into two major types. Depending on what the cancer cells look like, they are either non-small cell lung cancer (NSCLC) or small cell lung cancer (SCLC). Although both types start in the lungs, they each grow and spread in different ways. Treatment is also different for each type.
Non-small cell lung cancer, or NSCLC, is the more common one. It grows and spreads more slowly than the small cell variety. Small cell lung cancer, or SCLC, is less common. It also grows and spreads more quickly, and has a greater tendency to metastasise (spread to other organs).
Lung cancer takes years to develop, and in many cases it spreads widely before it is detected. In the early stages, there are often no symptoms. In more advanced stages, symptoms may include a persistent or chronic cough, blood in the sputum and shortness of breath. Other signs to watch out for may be pain in the chest when breathing, wheezing and recurring bronchitis and pneumonia.
Smoking has long been identified as the leading cause of lung cancer, and it is a cause that can be eliminated if you quit smoking before cancer develops. You can greatly reduce your risk, while allowing your lung tissue to regenerate.
Surgery is currently the best course of treatment for patients with early stage cancer. For patients in advanced stages or unfit for surgery, chemotherapy and/or radiotherapy are the preferred treatment options. In chemotherapy, anti-cancer drugs are used to stop cancer cell growth. Iressa, by AstraZeneca, is a new anti-cancer drug that blocks the growth signals in cancer cells.
It was first used in Singapore as part of a trial in the latter part of 2001, and given on 'compassionate basis'. An oral drug, Ixessa can be used by patients who are otherwise unfit for chemotherapy, or who have failed to respond to chemotherapy.
"Patients with lung cancer who have failed chemotherapy, that, means chemotherapy is no longer effective can try Iressa," stressed Dr Ang Peng Tiam, Consultant Medical Oncologist, Mount Elizabeth Medical Centre. "Otherwise, chemotherapy is still the preferred treatment for patients with advanced lung cancer, as the response rate is still significantly higher than Iressa."
Commenting on the drug's effectiveness, Dr Ang explains that, "Out of every 10 patients that take Iressa, five patients will experience no benefit - the tumour continues to grow, for three patients, the tumour remains stable - it stops growing, and in two patients, the tumour gets smaller."
This is in line with a clinical trial for the drug, conducted in Europe, Australia, South Africa and Japan, in which 18.4 per cent of patients who were given the drug had a symptom improvement rate of 40.3 per cent.
Iressa is currently available in Singapore for the treatment of advanced non-small cell lung cancer. It is an anti-cancer drug that can be taken orally, as a tablet, with mild side effects eg rash arid diarrhoea.
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