The immune system, our body's natural defence, has been shown to play a major role in the body's response to cancer. Immunomodulatory drugs may help the immune system fight cancer or lessen the side-effects from other cancer treatment. A clinical trial is underway in Hong Kong to see if these immunomodulatory drugs may improve the management of patients with lung cancer. More than 3,000 cases of lung cancer are diagnosed each year in Hong Kong, says Dr Raymond Liu Wai-to, senior medical officer, Department of Respiratory medicine at the Ruttonjee Hospital in Hong Kong. Ten per cent of these patients only survive five years. The only curative treatment at the moment is surgery, but only a quarter of all patients make it to the surgical table, with the rest being beyond curative treatment. Most of these patients require supportive care or some sort of chemotherapy or radiotherapy. 'Unfortunately current treatment is not satisfactory and most patients respond only moderately to chemotherapy,' he says. One of the ways to tackle the disease is to understand it better, he says. Epidemiological data show that lung cancer in males is correlated to smoking. This is not the case for females and environmental smoke alone cannot explain the etiology. There is also a genetic predisposition, though Dr Liu says there is genetic variation. 'So far, no single causative gene has been found to apply to all patients so we still have to find a genetic connection.' There is no effective way of diagnosing the disease early and most patients diagnosed are already in the advanced stage of the disease. 'About 30 per cent of the patients are in the advanced stage when first diagnosed,' says Dr Liu. There has been no major progress, with lung cancer treatment. 'We just cannot improve the mortality rate in lung cancers,' says Dr Liu. 'We have seen major advances in other cancers, for instance with the use with the use of bone marrow transplantation in the treatment of leukaemia. We have also seen improvements in breast cancer treatment. 'Unfortunately, there has been no major progress with lung cancer, even after surgery.' Advances in molecular biology have played a part in the detection of the disease. This has also helped in the understanding and the management of the disease. 'For example, we know that the immune system is involved in some sorts of cancers. We also know that cancer also suppresses the immune system.' The immune system has been shown to help kill cancer cells. It is our own body's defence. Tumours are regarded as a foreign body. 'If you boost the immune system to kill the tumour cells, it might be another way to tackle the problem,' he says. Paradoxically, while chemotherapy is used to fight cancer cells, it also suppresses the immune system. Additionally, chemotherapy, while killing tumour cells also kills normal cells. 'Hence we hope to be able to find different pathways to kill these tumours. 'We hope that thymosin-alpha 1, an immunomodulatory drug, will be beneficial in this respect. It has no marked side-effects and has been shown to boost the immune system.' Dr Liu is involved in a clinical trial in Hong Kong using thymosin-alpha 1 on lung cancer patients. Dr Liu explains that the aims of the trial; to see if the survival rate with current chemotherapy can be improved with thymosin-alpha 1; if it reduces the side-effects from chemotherapy and hence improve the quality of life (as it boosts the immune system); if thymosin-alpha 1 can alter an immune system that has already been affected by chemotherapy - that is, to speed up the restoration of the immune system. 'We are doing this because of the limitations of current treatment. We want to see of the immune system works faster with this drug. 'We chose this drug because it is not harmful and, theoretically, it stimulates the body's natural defence.' 'We get a lot of lung cancer patients each year. We all hope to do something to improve the dismal outcome of these patients,' he says.