Early detection and early treatment of prostate cancer

   Prostate cancer is not so “terrible”. Early detection and early treatment have huge advantages, and European and American countries have come to the fore in this regard. Take the situation in the United States as an example. Among the newly diagnosed prostate cancer cases, nearly 91% of the patients have clinically limited prostate cancer. These patients have a good prognosis after undergoing radical surgery or radical radiotherapy, and the 5-year survival rate is close to 100%. On the contrary, only 30% of new cases in my country were clinically limited patients at the time of diagnosis, and the others were patients with advanced or extensive metastases. These patients cannot receive local radical treatment, and the prognosis is poor. It can be seen that early detection and early treatment are important measures to prolong the life and improve the quality of life of prostate cancer patients. So, how to find the “clues” of prostate cancer as early as possible?
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   early detection of prostate cancer is one of the important means is that prostate cancer screening. The mortality rate of prostate cancer in the United States has declined in recent years, partly due to extensive and stringent prostate cancer screening.
   Since my country has never conducted a large-scale prostate cancer screening, there are a considerable number of highly aggressive or advanced prostate cancer cases in the population. Therefore, it is very necessary to carry out prostate cancer screening in our country. It is generally recommended that men over the age of 50, or men over 45 with a family history of prostate cancer, undergo prostate cancer screening based on prostate specific antigen (PSA) testing, provided that they are fully informed of the screening risks.
   PSA is mainly confined to prostate tissue, and PSA in serum is maintained at a low concentration level. There are two forms of PSA in serum, one part is free PSA (f-PSA), accounting for about 10% to 40%; the other is called bound PSA (c-PSA), accounting for about 60% to 90%. Usually the sum of f-PSA and bound PSA is called total serum PSA (t-PSA). When the prostate becomes cancerous, normal tissue cells are destroyed, a large amount of PSA enters the blood circulation, and the serum PSA rises. The criterion for PSA results is that the total serum PSA (tPSA)>4.0 ng/ml is abnormal, and those with abnormal PSA at the first inspection need to be reviewed. The serum PSA level of patients is affected by factors such as age and prostate size. When the total serum PSA is between 4 ng/ml and 10 ng/ml, fPSA has certain auxiliary diagnostic value. my country recommends fPSA/tPSA “0.16 as the normal reference value. If the patient’s tPSA level is between 4 ng/ml and 10 ng/ml, and fPSA/tPSA <0.16, a prostate biopsy is recommended.    In addition, the prostate volume is measured by ultrasound or other methods, and the PSA density (PSAD) is calculated; the greater the PSAD, the greater the possibility of clinically significant prostate cancer. In addition, PSA speed (PSAV) and PSA doubling time (PSADT) can also be calculated by time. These two indicators have a certain effect on the prognosis of prostate cancer patients. However, at the beginning of the diagnosis, due to many interference factors, the significance is relatively small.    In recent years, new diagnostic indicators have gradually emerged. Among them, PSA homoisomer 2 (p2PSA) and its derivatives, as well as evaluation indicators such as the prostate health index (PHI) have gradually attracted attention. p2PSA is associated with prostate cancer and high-grade prostate cancer. PHI is more effective than tPSA in diagnosing prostate cancer and can reduce unnecessary prostate biopsy. Other diagnostic indicators include the following items.    Prostate Specific Membrane Antigen (PSMA)    PSMA is a membrane-bound glycoprotein with high specificity for benign and malignant prostate epithelial cells. Normal men's serum can detect PSMA, while prostate cancer patients have higher PSMA values.    Long non-coding RNA prostate cancer antigen (PCA3)    PCA3 is a factor expressed in prostate cancer. It has been approved by the US FDA as a marker for the diagnosis of prostate cancer. In patients with elevated PSA, using PCA3 as a diagnostic marker can improve the diagnostic accuracy of prostate cancer more than using tPSA, fPSA, etc. It is recommended to perform PCA3 testing in patients whose initial prostate puncture is negative but still suspected of prostate cancer.    Digital rectal examination (DRE)    DRE has important reference value for early diagnosis and staging of prostate cancer. The typical manifestation of prostate cancer is palpable hard nodules of the prostate, with unclear borders and no tenderness. If the prostate nodules are not touched, prostate cancer cannot be ruled out. Comprehensive considerations such as PSA and imaging tests are required. DRE squeezing the prostate can lead to PSA human blood and affect the accuracy of the serum PSA value. Therefore, it should be performed after the patient's PSA blood test.    Magnetic resonance imaging of the prostate (MRI/MRS)    MRI is one of the most important methods for diagnosing prostate cancer and clarifying the clinical stage. The characteristic manifestation of prostate cancer is that there is a low signal lesion in the T2-weighted image of the peripheral zone of the prostate, which is obviously different from the normal high signal peripheral zone; in addition, the tumor area often shows the characteristics of early enhancement. Prostate MRI can show the integrity of the peripheral capsule of prostate cancer, whether it invades the fat tissues around the prostate, such as the bladder and seminal vesicle organs, and whether there is metastasis in the lymph nodes, etc., which plays an important role in the clinical staging of prostate cancer.    The use of multiparametric MRI (mpMRI) in staging and prostate cancer characterization has increased. To be considered "multi-parameter", MRI images must include images obtained by at least one sequence other than T2-weighted images, such as diffusion weighted imaging (DWI) or dynamic enhancement (DCE). In addition, high-quality mpMRI requires a 3.0T magnet.    mpMRI can help in terms of whether the extracapsule is invaded, and the results can provide information for decision-making in conservative neurosurgery. Once again, mpMRI is comparable to CT in the assessment of pelvic lymph nodes. Finally, for the detection of bone metastases, mpMRI is better than bone scan and CT.    Magnetic resonance spectroscopy (MRS) is based on the differences between the metabolism of citrate, choline and creatinine in prostate cancer tissues and the differences in prostate hyperplasia and normal tissues, showing different spectral lines to reflect the changes in cell metabolism in the body. To make up for the shortcomings of conventional MRI, it also has certain reference value for the early diagnosis of prostate cancer.    Genetic testing    The overall incidence of metastatic or localized high or low risk of prostate cancer in male patients, DNA repair gene mutations which were 11.8%, 6% and 2%. The new understanding of the mutation frequency of DNA repair genes is of great significance for family genetic counseling and better assessment of the individual's risk of secondary cancer. Ask about family and personal cancer history. If familial cancer syndrome is suspected, genetic counseling is recommended.    Bone scan    bone scan evaluation is currently the most common method of prostate cancer bone metastases. The sensitivity and specificity of the bone scan were 79% and 82%, respectively. The positive rate of localized prostate cancer was 6.4%, and the positive rate of locally advanced prostate was 49.5%. When there are symptoms of bone pain, a bone scan must be performed regardless of other indicators and clinical stage.    Application of PET-CT    C-11 Choline PET-CT has been used to detect and distinguish prostate cancer from benign tissues. The sensitivity and specificity of this technique in patients with biochemical recurrence and staging were 85% and 88%, respectively. C-11 Choline PET-CT may help detect distant metastases in these patients.    Prostate-specific membrane antigen (PSMA) is specifically and highly expressed on the surface of prostate cancer cells, and has extremely important research value in the field of prostate cancer molecular imaging and targeted therapy. In particular, radionuclide-labeled PSMA small molecule inhibitors have been used in prostate cancer. In terms of molecular imaging diagnosis, it shows good clinical application prospects. The sensitivity of 68Ga-PSMAPET-CT for the diagnosis of prostate cancer patients is 86%, and the specificity is 86%; the sensitivity for prostate cancer lesions is 80%, the specificity is 97%, and the diagnostic accuracy is much higher than that of traditional imaging examinations. .    Prostate biopsy    transrectal or transperineal prostate biopsy system is an important means of diagnosis of prostate cancer. The main limitations are false negatives, missed diagnosis of high-risk prostate cancer, and overdiagnosis. How to avoid overdiagnosis while increasing the positive rate of puncture is a huge challenge in the early diagnosis of prostate cancer. In recent years, prostate biopsy targeted by contrast-enhanced ultrasound, ultrasound elastography, and multi-parameter MRI has shown obvious advantages in detecting clinically significant prostate cancer and avoiding over-diagnosis.    MRI-guided targeted puncture can directly extract suspicious lesions under the guidance of MRI, with the highest accuracy. MRI-guided prostate biopsy can increase the detection rate of high-grade prostate cancer during repeated punctures. But the operation is relatively complicated and expensive.    The MRI/TRUS fusion technology combines the accuracy of MRI positioning and the convenience of transrectal ultrasound-guided puncture. While significantly increasing the positive rate of puncture, it can increase the proportion of clinically significant prostate cancers and avoid the detection of non-clinically significant prostate cancers. , Compared with puncture under MRI, the operation is more convenient.    Early treatment of prostate cancer    early treatment of prostate cancer include the following points.    Watchful waiting and active monitoring Watchful waiting includes monitoring the course of prostate cancer, in order to provide timely palliative treatment when symptoms appear, test results change, or PSA indicates that symptoms are about to appear. The purpose of observation is to maintain the patient’s quality of life by avoiding non-curative treatments when prostate cancer is unlikely to cause death or significant disease. It is generally applicable to patients in various stages whose life expectancy is less than 10 years.    Active monitoring includes active dynamic monitoring of the disease process, in order to take timely intervention measures for the purpose of radical cure when the tumor is detected, and it is mainly suitable for low-risk prostate cancer patients with a life expectancy of more than 10 years. The purpose is to postpone possible curative treatment and reduce possible side effects caused by treatment without affecting the overall survival. Once the tumor is found to be progressing, treatment should be started immediately so as not to miss the chance of cure.    The purpose of radical prostatectomy is to completely remove the tumor while preserving the function of urinary control and preserving erectile function as much as possible. Surgery can use open, laparoscopy, and robot-assisted laparoscopy. Regardless of the surgical method, experienced surgeons have a lower proportion of postoperative pathological resection margins and better control of tumors.    Radical external radiotherapy is one of the most important radical treatments for prostate cancer patients. There are three-dimensional conformal radiotherapy, intensity-modulated conformal radiotherapy, and graphic-guided radiotherapy, which have become the mainstream technology of radiotherapy. External radiotherapy has the advantages of good curative effect, wide indications, low complications and adverse reactions, etc. It can achieve similar curative effects as radical surgery for low-risk prostate cancer patients.    Brachytherapy is a technical method for the treatment of localized prostate cancer. Through the accurate positioning of the three-dimensional treatment planning system, radioactive particles are implanted into the prostate, which can increase the local dose of the prostate and reduce the radiation of the rectum and bladder. dose. The curative effect is positive and the trauma is small, especially suitable for elderly prostate cancer patients who cannot tolerate radical prostatectomy.