Can lung cancer be detected by chest X-ray during routine physical examination?

The answer is yes, but it can only detect part of it, and the missed diagnosis rate is not low. It is really not enough to rely solely on it for early screening of lung cancer.

I met a 47-year-old Chen at the physical examination center a while ago. He had taken chest X-rays for routine physical examinations at the workplace for six consecutive years, and the reports were all "no obvious abnormalities." Last month, he went to the respiratory department to register for a low-dose CT scan because his chest pain lasted for almost two weeks. A 2.3cm solid mass was diagnosed pathologically as invasive lung adenocarcinoma. I looked back at his chest X-rays from the previous two years and found that the tumor grew next to the mediastinum and was completely blocked by the shadow of the heart and large blood vessels. No abnormalities could be seen at all.

To put it bluntly, a chest X-ray is a "stacked photo" taken by flattening all the tissue structures of the chest, just like if you crush a whole orange with the skin and pulp into a pancake and then take a photo. The bruises on the skin can be seen, but the small rotten spots hidden next to the core in the pulp cannot be seen at all. Generally, only lung cancer lesions that are more than 2cm in diameter and are not blocked by structures such as ribs, heart, and mediastinum can be seen on chest X-rays. However, by the time the lung cancer reaches such a large size, many of them have already passed the earliest stage, and even local lymph node metastasis has occurred.

There are actually different voices in the industry regarding the use of chest X-rays to screen for lung cancer during physical examinations. One group believes that chest X-rays are low-cost and have low radiation. There is no harm in doing routine physical examinations. At least some conspicuous lesions can be found, which is better than no examination at all.； The other group believes that for people at high risk of lung cancer, taking only chest X-rays is equivalent to "ineffective screening". On the contrary, it will make people who get normal reports relax their vigilance. It will be too late to wait until they have symptoms before checking. It is better to directly use low-dose CT as a routine screening item for high-risk groups.

Of course, this does not mean that a chest X-ray is completely useless. If it has caused atelectasis, a large amount of pleural effusion, or an obvious mass close to the chest wall, the chest X-ray can still detect abnormalities immediately, point out the direction for subsequent examinations, and diagnose common chest problems such as pneumonia, tuberculosis, and rib fractures. The cost-effectiveness of the chest X-ray is still irreplaceable.

If you have no high-risk factors such as smoking, family history of lung cancer, or long-term exposure to dust/oil fumes, it is absolutely fine to have a chest X-ray for routine physical examination every year. However, if you meet the criteria for high-risk groups, don’t save money. A low-dose spiral CT every 1-2 years is much more reliable than taking a chest X-ray every year. If the lesions grow to the extent that they can be seen on the chest X-ray, it will be a bit of a delay.