Lung nodule is a “white spots,” or a “lump” in your lungs that is 3 centimetres or smaller in diameter. Like people have lump in their breasts, same way people can have a lump or several lumps in their lungs. The only difference is that if someone has a lump in their breast, they can feel it, whereas we cannot feel the lump in our lungs because our lungs are inside our chest. 

If 500 people do a chest X-ray, a nodule will be found in one of them. If 100 people undergo CT scan of the lungs, a nodule will be found in one of them. This means that CT scan is more accurate in picking up a nodule (spot) in your lungs than a chest X-ray. A nodule needs to be at least one centimeter in size before they can be seen on a chest x-ray, whereas nodules as small as one millimeter can be seen on a CT scan making it a more accurate test. 

About half of the people over the age of 50 who smoke will have nodules on a CT scan of their chest. The factors such as long history of smoking which means smoking at least 20 cigarettes a day for 15-20 years, or a specific shape of the nodule can provide a clue to whether a nodule is cancerous or not for example a nodule that has a shape that resembles “sun rays around the sun” is suggestive of cancerous nature of the nodule.

However, such clues are only clues, they do not provide confirmation about the nature of the nodule. For instance, a nodule can still be cancerous in person who never smoked, or in person with a round nodule instead of sun ray appearance. For confirmation, a biopsy (taking a small sample of the nodule) is always needed. 

The good news is that about 60 percent of lung nodules overall—are not cancerous. Even if a nodule is lung cancer there is still a good chance that it can be cured. An important point to note is that finding out what the nodule is made up of is important even if you’ve never smoked or you are young. At the current time, there are more former smokers and never smokers who develop lung cancer, than people who smoke.

Anyone who has lungs can get lung cancer regardless of smoking habit, and in fact, lung cancer has been significantly increasing among young, never-smoking women. Lung nodules don’t cause any symptoms and hence their detection is solely dependent on how actively someone is looking for it like one looks for colon cancer or breast cancer by a 2 yearly colonoscopy and mammography respectively.

However, unlike colon, breast or cervical cancer, there are no guidelines suitable for screening of lung cancer in the Asian countries. The lung cancer screening protocols that are used in USA, and which have reduced the risk of dying from lung cancer by screening are hard to adopt in Singapore or Asian countries.  

As stated above, not all nodules are cancerous. Some are benign (non-cancerous). The most common benign cause of nodule in Singapore is TB or NTM (a cousin of TB germ) or a fungal infection. 

The first thing your doctor will want to do if he sees a lung nodule on your X-ray is to obtain any previous X-rays you have had and compare them. If the nodule or nodules have been present for a long time, further tests may not be needed. However, if the nodule on the X-ray is new, a CT scan will be the first test to be done. 

What can you do? If you have been told that you have a lung nodule based on a chest X-ray, and if you do not have any pervious chest X-ray or CT scan done in the past, you will need a CT scan and you should ask your doctor for it. If you do have a previous chest X-ray or CT scan, do try to find it and bring to your doctor for comparison with the current chest X-ray. If your nodule has been diagnosed based on a CT scan, and if its new, you need to consider if you have a personal or a family history of cancer, or a significant (1 pack a day for 15-20 years or more) history of smoking. If you have any of the above, it may be advisable to go for the biopsy of your nodule to find out with certainty whether your nodule is cancerous or not.