What is disease screening

To put it bluntly, disease screening is to conduct targeted examinations for people who do not have any symptoms, and actively select early lesions hidden in the body, or people with high risk of disease in advance. It is essentially a means of "actively preventing disease", and the benefits are much higher than intervention after the disease has occurred.

The cervical TCT screen for cervical cancer, the low-dose spiral CT screen for lung cancer, and the Helicobacter pylori insufflation test screen for gastric cancer risk that we often do in our daily physical examinations are all typical screening items - you wouldn't wait until you have contact bleeding, cough up blood, or have stomach pain every day before doing these tests, right? I always take the initiative to check when I don’t feel anything at all. When I was doing a public health screening project in the community, I met several old smokers in their early 40s. They thought it was normal for them to be old when they climbed stairs to breathe. After a long time of persuasion, they were willing to do a free low-dose CT scan. The result was ground glass nodules. After the surgery, the pathology was early cancer, and they didn’t even need chemotherapy. If they delay the symptoms for another year or two, they will most likely be in the middle and late stages. Spending money and suffering may not necessarily lead to good results.

If you compare diseases to landmines buried in the body, screening is equivalent to scanning them regularly with a metal detector. Digging out hidden dangers in advance before the landmines explode (symptoms appear) is low cost, low risk, and effective.

However, there have been a lot of controversies about screening in recent years, and the core focus is on the "degree". It’s not that the more frequent the screening, the more expensive the project, the better. For example, many people ask for thousands of dollars of PET-CT to screen for systemic cancer. But for ordinary young people with no family history of cancer and no high-risk factors, this not only has a high radiation dose, but also has a high probability of false positives. It may frighten half to death when a small nodule is found. There are punctures and follow-ups, and after a lot of trouble, the result is benign. It is purely a waste of money. In the past two years, Europe and the United States also adjusted the recommended starting age for breast cancer mammography screening from 40 to 45 years old. This is also because women aged 40 to 45 have high breast density and the false positive rate of mammography is too high, which will cause unnecessary excessive examination and anxiety. The overall benefits are not as good as not screening. Until now, there are still differences in the determination of this age threshold in different regions and different institutions, and there is no absolutely unified standard.

The current consensus in the industry is also very clear. There is no universal screening package. You have to choose the corresponding items based on your age, family history, and high-risk factors in your living habits. For example, those with a family history of lung cancer and smoking for more than 20 years should do low-dose CT early and every year. Those with a family history of cervical cancer and HPV infection should shorten the interval between TCT and HPV screening. Ordinary people can just follow the routine items recommended by the guidelines. There is no need to blindly pursue more, more expensive, and more complete screenings.