Why can’t routine physical exams detect cancer?

The answer is actually very simple - the routine physical examinations we usually do were not designed to catch cancer from the beginning. It is a small probability event that early-stage cancer can be found.

Last week, I met Uncle Zhang, a regular customer at the physical examination center. His annual physical examination organized by his work unit had failed. Last year's report was marked as "no obvious abnormality." In the spring of this year, he had a cough that didn't get better for almost two months. I went to the hospital for a low-dose spiral CT scan, and it was found to be mid-stage lung adenocarcinoma. He asked me if I had missed the diagnosis before with a stack of physical examination reports from previous years. I looked through his projects over the years, and they all included chest X-rays, routine blood tests, and liver and kidney functions. He had never even done a chest CT. Most of the nodules in early-stage lung cancer were only a few millimeters, and they couldn't be captured on a chest X-ray. How can we blame the previous physical examination for being inaccurate?

To put it bluntly, the core goal of routine physical examinations is to screen for common chronic diseases, such as high blood pressure, high blood sugar, and hyperlipidemia, as well as basic liver and kidney function, and thyroid dysfunction. It is equivalent to a routine annual inspection of the car you drive. It checks whether the brakes are working, whether the lights are bright enough, and whether the exhaust gas meets the standards. They will not disassemble the engine to find out whether there are any hidden dangers of early wear and tear. Routine physical examinations for cancer are essentially "beyond the scope of duties" requirements.

Nowadays, many people think that since the basics are not good, if I add money for a 10,000-yuan luxury physical examination package, I can always check it out, right? This has also been a controversial point in the industry: one school of thought believes that by packaging items such as tumor markers and PET-CT into high-end packages, "full coverage of early cancer" can be achieved. However, most of us in front-line clinical practice do not recommend this to ordinary people. Let’s take the tumor marker that everyone is familiar with. It may spike up after staying up late the night before, drinking alcohol, or even catching a cold and inflammation. If it is found to be high, you will be scared to death and go through a lot of reexaminations. In the end, nothing will happen. But if it is early-stage cancer, many times the tumor marker will not respond, but will give you false peace of mind. Not to mention PET-CT, the amount of radiation in one session is equivalent to 10 conventional CT scans, and the cost is several thousand dollars more. The sensitivity to early-stage tumors of hollow organs such as gastric cancer and intestinal cancer is particularly low. Ordinary people do random physical examinations and spend money purely on radiation.

It’s not that routine physical examination is completely useless. It is actually a health indicator. For example, if you smoke all year round, and the chest X-ray taken during routine physical examination shows that the lung texture is thickened, you should quickly get a low-dose spiral CT. If you often have stomach bloating and acid reflux, and the physical examination shows that Helicobacter pylori is positive, you should honestly make an appointment for a gastrointestinal endoscopy. These signals are actually reminders for you by routine physical examination. It is better than doing nothing and waiting until you feel pain or weight loss before going to the hospital.

In fact, our industry has been discussing in the past few years whether to include targeted screening items for high-risk cancers such as lung cancer and digestive tract cancer into the optional package of routine physical examinations based on age and high-risk factors. There are many voices of opposition: if all are included, the cost of routine physical examinations will at least triple or four times, which will make many people with low incomes reluctant to even do basic physical examinations. In the end, it will increase the overall proportion of late detection of serious diseases. How to balance cost-effectiveness and coverage is not yet accurate.

To be honest, if you really want to prevent early cancer, don’t just look at the “no abnormality” in the routine physical examination and think everything is fine. First, identify the high-risk factors for yourself: whether you have a family history of cancer, whether you smoke, whether you have chronic gastritis and enteritis, and add 1-2 special screenings. It is much more effective than spending tens of thousands on a luxurious full-body physical examination. But don’t wait until symptoms actually appear before you think of follow-up examinations. By then, most of them have missed the best treatment period.