Lung Cancer Screening in Singapore

Lung cancer is the leading cause of death from all types of cancers in Singapore. Smoking remains the leading cause of lung cancer although even when one stops smoking, the risk remains elevated. Lung cancer is increasingly found in those who have never smoked.

The leading type of lung cancer is called non-small cell cancer, which accounts for up to 75 percent of all lung cancer types. Unfortunately, it is usually not detected until the cancer has advanced locally or has metastasized to other body areas. The five year survival rate of people with non-small cell cancer is about 15 percent. If the cancer is surgically removed, it increases the survival rate to 75 percent.

The tests recommended for screening of lung cancer have included chest x-ray and sputum cytology studies. The use of either the chest x-ray and sputum cytology is not recommended for screening and the low dose CT scan for lung cancer screening is also not recommended. There have been a number of clinical trials looking at CT scan for finding lung cancer but it is still not recommended for the average person.

The individual considered high risk for lung cancer includes former and current smokers and those exposed to industrial fumes and particles, such as asbestos. There hasn’t been, however, a universally accepted group of these individuals who have actually found benefit from screening for lung cancer by any means. The use of serial x-rays of the chest for lung cancer screening is not currently recommended. Sputum cytology has been looked at, as has low dose CT scan of the chest but neither has shown to increase survivability of lung cancer.

Part of the problem is that, while more lung cancers are discovered using a screening process, the treatments of lung cancer haven’t caught up with screening so that the screening doesn’t reduce morbidity and mortality of the disease. There is less money going toward lung cancer research than is going to other cancers, such as colon and breast cancer.

Low dose CT can detect 2-4 times more lung cancers than does the chest x-ray. It detects lung cancer when it is smaller, in the range of 9-16.5 mm in diameter. The other problem is that more than 90 percent of CT-found nodules were benign, even in a high risk population. This can mean that a patient undergoes unnecessary further testing in order to define the cause of the nodule. Treatment may be initiated, even when it isn’t necessary. Serial CT scans to watch the growth of the nodules is expensive but is an option for those who don’t want an open lung biopsy and may be more cost effective.

Lung cancers consist of numerous genetic abnormalities, some of which show up in pre-malignant lesions. These can be checked through the use of biomarkers in the sputum or the blood and may be a useful screening tool in the future. Auto-fluorescence bronchoscopy is another screening tool that can tell the difference between premalignant and malignant lesions of the lung in the bronchial epithelium. It is not yet recommended for routine use as a screening method for lung cancer.

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