Principles of disease screening

The benefits outweigh the risks, and individual adaptation is prioritized. All seemingly complex screening guidelines and clinical decisions are essentially derived around these two cores.

A while ago, I met a 30-year-old Internet worker in the outpatient clinic. His work unit bought him a high-end physical examination package. He checked a full set of tumor markers and found out that CA724 was twice as high as the normal value. He was so scared that he ran to three hospitals in a row and had a gastrointestinal endoscopy and a chest and abdominal CT scan. It took less than half a month. In the end, it was discovered that he had eaten spicy hot pot and stayed up all night before the physical examination the day before, and the indicators had only temporarily increased. He suffered a lot in vain.

Many people’s first misunderstanding about screening is that “the more complete, the better, the more expensive, the more accurate.” In fact, this is not the case at all. The principle of "benefit outweighs risk" puts it bluntly: the benefits you get from doing this screening must far outweigh the cost of money and time you pay, as well as the possible costs of excessive examination harm and anxiety.

This is also the most controversial direction in the industry. For example, there has been an argument for several years about "should healthy young people undergo low-dose CT screening for lung cancer?" The views of both groups are fully supported by data: the supporters believe that the radiation dose of low-dose CT has dropped to about 1mSv, which is almost the same as taking 10 long-distance flights. The cure rate of early-stage lung cancer is close to 100%. As long as one case of early cancer can be detected, it will be worth all the costs; but the opponents, such as the United States Preventive Services The current guidelines of the working group (USPSTF) still do not recommend that people under 50 years old and without high-risk factors for lung cancer undergo routine screening. The core basis is that the prevalence of lung cancer in this group is less than 0.1%, which is equivalent to every 1,000 CT scans. Only one true patient can be identified. Among the remaining 999 people, there may be 20 or 30 people who will be diagnosed with small pulmonary nodules of unknown nature. Subsequent reexaminations and even invasive punctures will be required to confirm. Many people will be anxious about this nodule for several years, which is not worth the gain. I myself met a 28-year-old girl who did not smoke and had no family history. A 4mm ground-glass nodule was found in a physical examination. There was no change in the nodule after 3 years of follow-up. During those 3 years, she did not even dare to get married. She always felt that there was a time bomb in her body. This kind of emotional consumption is actually an invisible risk of screening.

As for "individual adaptation first", it is easier to understand - there is never a standard answer to screening that is universally applicable. It may be completely unnecessary for others to apply items that are suitable for you. For example, for a 45-year-old woman, if her mother and grandmother have had breast cancer, and she is unmarried and has no children, she will definitely start doing mammography combined with ultrasound screening 5-10 years earlier than ordinary women, and even add BRCA gene testing; but if there is no family history, normal childbirth and breastfeeding, and no abnormal symptoms such as breast tenderness and discharge, screening at the frequency of conventional guidelines is enough, and there is no need to spend extra money for projects such as PET-CT.

Speaking of PET-CT, it was really popular in the past two years. Many people regard it as a standard for high-end physical examinations. The most exaggerated boss I have ever seen was to do PET-CT twice a year. Good guy, the radiation dose of one PET-CT is almost 20 chest X-rays. If a healthy person has no high-risk factors for tumors and no suspicious symptoms, doing this will increase the risk of radiation-induced cancer. It is completely worth the money.

When I give screening recommendations to relatives and friends, I usually ask three questions first: Is there a family history of related diseases? Are there any high-risk factors for long-term exposure (such as smoking, long-term exposure to kitchen fumes, formaldehyde and other pollution in the working environment)? Are there any unusual symptoms that persist for more than two weeks? Take one out of three, and then consider whether to add items in addition to the basic screening. Otherwise, the basic package based on age is really enough.

Of course, this does not mean that the more conservative the better, don’t be lazy if you really have high-risk factors. Last year, I met a 42-year-old smoker who had been smoking for 20 years, a pack a day. He had been advised several times to have a lung CT every year. He always felt that it was unnecessary if he didn’t cough and it didn’t hurt. He finally came to see a doctor after he coughed up blood. He was found to have advanced lung cancer, and even the chance of surgery was gone. It’s really a pity to say that.

To put it bluntly, disease screening has never meant that the more projects you do and the more money you spend, the more responsible you are for your own health. Just like you would not buy postgraduate entrance examination materials for a child who has just entered elementary school. Suitability, cost-effectiveness, and usefulness for yourself are the core criteria. When you are really not sure what to do, it is much more reliable to chat with a reliable general practitioner for 10 minutes than to add random items on your own based on various popular science information on the Internet.