A friend came to ask: [The unit organizes physical examination. The three tumor markers CEA, AFP and CA-125 are optional. It is said that cancer can be checked, but it is a little expensive. Do I want to choose? ]
Do you want to be a tumor marker? It must be more than one person who is confused.
First of all, let’s talk about the conclusion: if your relatives and family members do not have relevant tumor history, they do not have bad habits (such as smoking) and related chronic diseases (such as hepatitis), and they are still young (less than 40 years old), there is not much need to do tumor marker screening during physical examination.
Because, it is found that the marker is elevated, and it is very likely that there is no cancer in fact.
However, some companies now brag too much about the role of tumor markers for profit. In fact, it is not magical as imagined. Today, let’s unveil the mystery of tumor markers.
More than 98% of the people were a false alarm.
There are two indicators to measure the accuracy of any medical examination.
False positive rate: It is the probability that healthy people who are not sick are mistakenly regarded as sick according to the examination results.
False negative rate: that is, the patient is mistakenly regarded as a healthy person according to the examination results.
Perhaps everyone is a little dizzy. To give a simple example, AFP, the most commonly screened tumor marker, is the most important tumor marker for screening and diagnosis of liver cancer. However, relevant studies show that AFP has 34% false positive rate and 19% false negative rate for early diagnosis of liver cancer.
It may be more intuitive for us to change to specific data. For every 1,000 high-risk groups screened, about 5 people were found to have liver cancer (0.56% of the high-risk groups in the community were screened for 3 years). Then 34% × (1,000-5), 338 patients were false positive and 81% × 5, 4 patients were true positive. A total of 338 +4,342 patients were found to be AFP positive. That is to say, 98.83% (338 out of 342) of these AFP positive patients were false alarms.
However, if the marker test is negative, you can rest assured.
Why is it so [not allowed]?
The reason for this situation is that AFP will also increase in hepatitis, liver cirrhosis, pregnancy and embryonic tumor diseases, leading to some [misdiagnosis]. AFP negative liver cancer (such as small liver cancer), AFP will not increase, leading to some [missed diagnosis].
Of course, no doctor will make a diagnosis of liver cancer based on only one AFP examination.
So, is there a tumor marker that can clearly diagnose a tumor or exclude a tumor?
I’m sorry to tell you that not yet.
This is why tumor markers rise, you must not be particularly nervous. In particular, the general survey of healthy people is basically false positive, because infection, inflammation, smoking, etc. will cause the rise of tumor markers.
Then why do you want to check?
Therefore, the clinical application of tumor markers is mainly the corresponding tumor screening for high-risk groups, as well as evaluating the curative effect after tumor treatment and monitoring recurrence.
For example, the most common markers we make are these:
- Hepatocellular carcinoma: AFP > 400 ng/mL for 8 weeks; Lung cancer: The positive rate of CEA for lung cancer diagnosis is 40% ~ 50%. NSE Assisted Diagnosis of Small Cell Lung Cancer; SCCAg Assisted Diagnosis of Lung Squamous Cell Carcinoma; Prostate cancer: PSA > 10 ng/mL increases the risk of prostate cancer; Colorectal cancer: CEA exceeding 20 ug/L often indicates digestive tract tumor; CA199 and CA242 make up for the deficiency of CEA to some extent; Ovarian cancer: CA125 > 35 U/mL, suspected to be malignant; CA125 > 70 U/mL, highly suspected malignant. Breast cancer: hormone receptors ER and PR, CEA, CA125, etc.