prostate health index

The Prostate Health Index (phi) is the most cost-effective serological assessment indicator currently used clinically to improve the accuracy of prostate cancer screening and reduce the proportion of unnecessary prostate punctures. For people whose PSA (prostate specific antigen) is in the "gray zone" of 4-10ng/ml, its prostate cancer diagnostic specificity is about 25% higher than the total PSA test alone, and can help at least 30% of the people in the gray zone avoid the pain of puncture.

Last week, I met a 48-year-old programmer named Lao Zhou at the outpatient clinic. His work unit showed a PSA of 7.9ng/ml. He searched for popular science all night and was so scared that he stayed up all night. The local hospital directly asked him to make an appointment for a puncture. When he came to me, he still held a mobile phone full of notes in his hand. I first prescribed a phi test for him, and the result came out three days later, which was 17.2, which is in the low-risk range. I told him that he didn’t need to wear it and could just have a recheck every six months. I still remember the breath he had at that time.

Many people think that phi is a new item that is measured separately. In fact, it is not. It is a comprehensive score calculated by substituting the values ​​of the three indicators of total PSA, free PSA, and subtype [-2] proPSA into a fixed formula. It is equivalent to filtering out the interference factors of the three independent indicators and integrating them into a more accurate risk judgment, which is much more reliable than looking at PSA alone.

Oh, by the way, the current risk cut-off value of phi is not completely unified in the academic community. The European and American Urology Association recommends 30 as the cut-off value. If it is higher than 30, it is recommended to further perform prostate magnetic resonance imaging or even puncture.； However, large-sample studies in China in recent years have found that the average prostate volume of Asian men is 15%-20% smaller than that of European and American men. If the critical value is lowered to 27, the sensitivity of screening will be higher. Last year's "China Prostate Cancer Screening and Early Diagnosis and Treatment Guidelines" also used this range as a reference. Clinics generally make comprehensive judgments based on the patient's age, family history, and prostate volume, without getting stuck on the numerical value.

In addition to the people whose PSA is in the gray zone mentioned just now, those who have a family history of prostate cancer, those over 45 years old whose PSA fluctuates more than 1ng/ml per year, and those whose previous puncture results were benign but whose PSA continues to rise, can give priority to checking phi to re-evaluate the risk. There used to be a 62-year-old retired teacher whose PSA hovered around 6 all year round. He had a puncture performed three years ago and it was found to be benign hyperplasia. After that, he had to worry about having his PSA rechecked every year for several months. Last year, he started to have additional phi tests, and the results were around 14 twice in a row. Now he comes for rechecks with ease and no longer has to think about whether he will suffer another puncture.

Of course, this does not mean that phi is omnipotent. You should pay attention to a few points before taking the test - if you are taking drugs such as finasteride and dutasteride to treat prostate hyperplasia, you must stop taking the drug for at least 3 months before taking the test. Otherwise, the drug will lower the PSA value and the calculated phi will not be accurate.； It is also best not to ride a bicycle for a long time, do not have a digital rectal examination, and do not have sex 3 days before the test, otherwise pressure on the perineum will also affect the index results. In addition, if phi is lower than the critical value, it does not mean that there is no risk at all. After all, less than 5% of special types of prostate cancer will not cause an increase in PSA. If you have symptoms such as difficulty urinating and pelvic pain, you still need to make a comprehensive judgment based on imaging examinations.

After all, phi is essentially a more accurate "prostate risk calculator". You don't need to be scared to death when you see an elevated PSA on the physical examination report, and don't think that phi is normal just because you sit and hold your urine, drink alcohol, and stay up late. Even if the indicators are fine for the time being, prostate hyperplasia and prostatitis will come sooner or later. After all, no matter how good the screening index is, it is not as practical as taking more care of the prostate.