Teach you to understand tumor markers

Tumor markers (TM) are routine items for cancer screening. They refer to substances that characteristically exist in malignant tumor cells, or are abnormally produced by malignant tumor cells, or are produced by the host in response to tumor stimulation.

Changes in tumor marker values ​​are a concern for those undergoing physical examinations. In fact, elevated tumor markers found in healthy people during physical examinations do not necessarily indicate tumors or cancer. They usually only indicate an increased risk of developing a certain type of cancer, and there may be false negatives or false positives, so there is no need to be too nervous. However, for patients who have been diagnosed with cancer, changes in tumor markers can help determine the efficacy of the treatment.

Why does a false positive occur? Even though there is no tumor, the tumor markers detected are elevated. This is a false positive.

This is because tumor markers are not only expressed in tumors, but are expressed at higher levels in certain tumors, which helps in the early detection of tumors and the selection of treatment options.

A positive test result does not necessarily mean a tumor. The following situations can also cause abnormal tumor markers: benign tumors, chronic inflammation, pregnancy, menstruation; poor sleep, taking medicines, supplements, drinking, smoking; rabies vaccination, etc., can all cause tumor markers to be high.

For example, elevated alpha-fetoprotein (AFP) is more common in primary liver cancer, ovarian and testicular germ cell tumors, but it can also be elevated in pregnancy, liver disease (hepatitis, cirrhosis, toxic liver damage), inflammatory bowel disease and other non-cancer factors. Some people's AFP is several times higher than the normal value, and further examination shows that they have inflammatory bowel disease. For another example, serum CA125 is a tumor marker, which is significantly elevated in patients with ovarian cancer. It is mainly used to assist in the diagnosis of malignant serous ovarian cancer, and is also an indicator for observation after postoperative chemotherapy for ovarian cancer. Some female patients had CA125 levels that were more than 30 times higher, and further examination revealed that they had pelvic tuberculosis; some patients had much higher CA125 levels, just because they happened to be menstruating during the physical examination.

Therefore, if a physical examination reveals elevated tumor markers, there is no need to panic and you should follow the doctor's advice for further examination.

Why does a false negative occur? Even though a person has a tumor, the corresponding tumor marker test results are normal. This is a false negative.

There are many types of cancer, and no good broad-spectrum "tumor marker" has yet been found. Different tumor markers have different sensitivities, and false negative results are common in testing.

Tumor markers with higher sensitivity include alpha-fetoprotein (AFP) and prostate-specific antigen (PSA), and their continued increase usually indicates the occurrence of tumors (primary liver cancer, prostate cancer). Even tumor markers with high sensitivity can have exceptions. For example, among 100 liver cancer patients, about 75 will have elevated AFP, and the other 25 may slip through the AFP screening net.

A significant increase in CA125 often indicates ovarian cancer, but there is a type of non-epithelial ovarian cancer in which the CA125 is lower or even within the normal range, so it may be missed.

The sensitivity of tumor markers related to some tumors, such as rectal cancer and colon cancer, is low, and the test results are often normal. Some tumor markers are normal in the early stage, and only when the tumor grows and the tissue necrotizes and falls off into the peripheral blood can the tumor markers be detected in the serum.

Therefore, a negative result does not mean that there is no tumor. Tumor markers can only be used as an auxiliary diagnosis method, and the diagnosis must be based on clinical symptoms, imaging, and especially pathology.

What to do if tumor markers are elevated? For healthy people, if tumor markers are only slightly elevated, it is recommended to recheck after one month, and recheck several commonly used markers. If the rechecks show normal results twice, it may be caused by benign lesions or inflammation. If a single test shows a particularly obvious increase, several or dozens of times the upper limit of the normal value, or if the dynamic increase continues after repeated tests, it means that the possibility of cancer is high, and further examinations must be performed for differential diagnosis.

For high-risk groups, such as those with a family history of breast cancer, ovarian cancer, colon cancer, etc., if the corresponding tumor markers are elevated, they should be closely monitored and further examined.

If tumor markers in cancer patients continue to rise before treatment, it means that the disease is in the late stage, metastasis may have occurred, and the treatment effect is relatively poor. After treatment, tumor markers are mainly used to monitor tumor progression and efficacy. If they continue to rise, it may be tumor recurrence or metastasis. You must consult a doctor immediately and do further examinations to determine whether to change the treatment plan. For example, when ovarian cancer recurs, CA125 can be elevated several months before the clinical diagnosis, which buys time for patients to receive precise treatment.