I. Incidence of prostate cancer.
There are obvious geographical and racial differences in the incidence of prostate cancer, with the highest in the Caribbean and Scandinavia, the lowest in China, Japan and the former Soviet Union countries, and the highest incidence of prostate cancer in the world among blacks in the United States. Although the incidence of prostate cancer in Asia is much lower than that in Europe and the United States, it has shown an increasing trend in recent years. In China, the incidence of prostate cancer in 1993 was 1.71 per 100,000 population and the mortality rate was 1.2 per 100,000 population; by 2000, it was 4.55 per 100,000 male population.
The risk factors for prostate cancer are not yet clear, but some of them have been identified. One of the most important factors is genetics. If one immediate family member (brother or father) has prostate cancer, his or her risk of developing prostate cancer increases by a factor of 1. The relative risk increases by a factor of 5 to 11 if two or more immediate family members have prostate cancer.
What are the symptoms of prostate cancer?
The clinical symptoms of prostate cancer and their severity depend on the speed of growth of the cancer and the degree of compression of the urethra. Because the prostate gland surrounds the urethra, the cancer first presses on the urethra and shows the symptoms of abnormal urination. At the beginning, frequent urination and increased nighttime urination can be seen; when the mass increases and presses the urethra, thin urine flow, poor urination and prolonged urination will occur; a few patients may experience painful urination and some may have hematuria, which should be alarmed at this time. When the cancer gradually increases, the urethra will be compressed more severely, making it difficult to urinate and causing urine retention in the bladder, causing the bladder to fill up and swell to a high degree, which is extremely uncomfortable. When prostate cancer metastases, especially pelvic metastases, pain in the lower back or symptoms similar to sciatica can occur, and the pain can often radiate to the perineum and around the anus, as well as pathological fractures, anemia, and lower limb paralysis due to spinal cord compression. In China, due to the lack of awareness of prostate cancer among men over 60 years old, few elderly people will take the initiative to have prostate examinations, resulting in most of the patients with prostate cancer found in our clinic are in the middle or late stage, losing the opportunity of radical treatment for prostate cancer.
How to diagnose prostate cancer?
Most prostate cancer patients can be diagnosed histopathologically through systematic puncture biopsy of the prostate. Rectal examination combined with serum prostate-specific antigen (PSA) test is currently recognized as the best primary screening method for early detection of prostate cancer! We usually perform PSA and rectal examination of the prostate first, and then perform prostate puncture biopsy if prostate cancer is suspected.
What other tests are needed for prostate cancer?
(1) Transrectal ultrasonography.
This test can show suspicious lesions in the prostate and surrounding tissues, and can determine the size of the tumor initially. However, its specificity is low and the detection of a hypoechoic lesion in the prostate has to be differentiated from a normal prostate, BPH, PIN, acute or chronic prostatitis, prostate infarction and prostate atrophy.
(2) Computed tomography (CT) examination.
CT is less sensitive than MRI for the diagnosis of early prostate cancer. The purpose of CT examination for prostate cancer patients is mainly to assist clinicians in clinical staging of the tumor. For the invasion of tumor adjacent tissues and organs and metastatic lymph node enlargement in the pelvis, the diagnostic sensitivity of CT is similar to MRI.
(3) Magnetic resonance imaging (MRI) scan.
MRI can show the integrity of the prostate envelope, whether it invades the tissues and organs around the prostate, and MRI can also show the invasion of the pelvic lymph nodes and the foci of bone metastases. MRI has an important role in clinical staging. In order to show the prostate and surrounding tissues more objectively, we recommend MRI examination before performing prostate puncture biopsy.
(4) Nuclear imaging (ECT) of prostate cancer.
The most common site of distant metastasis of prostate cancer is the bone. eCT can detect bone metastasis 3-6 months earlier than conventional X-ray, with higher sensitivity but less specificity. Once the diagnosis of prostate cancer is established, whole-body bone imaging is recommended to help determine the accurate clinical stage of prostate cancer.
V. How can prostate cancer be cured?
At present, only limited prostate cancer can be cured, that is, the tumor is confined to the prostate gland and does not break through the prostate envelope, and there is no bone metastasis. The most effective treatment for limited prostate cancer is radical prostatectomy, and there are three main procedures, namely traditional trans-perineal, retropubic and laparoscopic radical prostatectomy. The advantages of laparoscopic radical prostatectomy are less damage, clear field and anatomical structure, and fewer intraoperative and postoperative complications.
Endocrine therapy for prostate cancer.
Prostate cancer is a hormone-dependent malignant tumor. As early as 1941, Huggins and Hodges discovered that surgical debulking and estrogen could delay the progression of metastatic prostate cancer and first demonstrated the responsiveness of prostate cancer to androgen removal. Prostate cell death will occur in the absence of androgen stimulation. Endocrine therapy for prostate cancer aims to reduce the concentration of androgens in the body, inhibit the synthesis of adrenal-derived androgens, inhibit the conversion of testosterone to dihydrotestosterone, or block the binding of androgens to their receptors in order to inhibit or control the growth of prostate cancer cells.
Clinically, endocrine therapy is routinely divided into two aspects: on the one hand, inhibition of testosterone secretion: surgical debulking (bilateral orchiectomy) or pharmacological debulking (luteinizing hormone-releasing hormone analog, LHRH-A); on the other hand, blocking the binding of androgens to their receptors: application of anti-androgen drugs to competitively close the binding of androgens to the androgen receptors of prostate cells. The combination of the two can achieve the maximum effect of androgen blockade.