What is prostate cancer

Prostate cancer is an epithelial malignant tumor that occurs in the prostate. In the 2004 WHO "Pathology and Genetics of Tumors in the Urinary System and Male Genital Organs", the pathological types of prostate cancer include adenocarcinoma (acinar adenocarcinoma), ductal adenocarcinoma, urothelial carcinoma, squamous cell carcinoma, and adenosquamous carcinoma. "Prostate adenocarcinoma accounts for over 95% of these cancers, so what we usually refer to as prostate cancer is prostate adenocarcinoma.". In 2012, the incidence rate of prostate cancer in tumor registration areas in China was 9.92/100000, ranking sixth in the incidence rate of male malignant tumors. The onset age was at a low level before 55 years old, and gradually increased after 55 years old. The incidence rate increased with age, and the peak age was 70-80 years old. Patients with familial inherited prostate cancer have an earlier onset age, with 43% of patients aged ≤ 55 years.

Basic information

English name: carcinomaof state

Visiting department Oncology Department

Frequently occurring group aged 70-80

Common etiological genetic factors

Infectious None

Etiology

The occurrence of prostate cancer is related to genetic factors. If there is no prostate cancer in the family, the relative risk is 1, and the absolute risk is 8; The relative risk of prostate cancer among members of the hereditary prostate cancer family is 5, and the absolute risk is 35 to 45. In addition, the incidence of prostate cancer is related to sexual activity and dietary habits. People who have more sexual activity have an increased risk of prostate cancer. A high fat diet is also associated with morbidity. In addition, the incidence of prostate cancer may be related to race, region, and religious beliefs.

Clinical manifestations

Prostate cancer often has no symptoms in the early stage. As the tumor develops, the symptoms caused by prostate cancer can be summarized into two categories:

1. Compression symptoms

Progressive urination difficulties can be caused by gradually increasing prostate gland pressure on the urethra, manifested by thin urinary lines, short range, slow urinary flow, interruption of urinary flow, dripping urine after urination, endless urination, and laborious urination. In addition, there are frequent urination, urgency, increased nocturnal urination, and even urinary incontinence. "Tumor compression of the rectum can cause difficulty in defecation or intestinal obstruction, as well as compression of the vas deferens causing ejaculation deficiency, compression of the nerves causing perineal pain, and radiation to the sciatic nerve.".

2. Metastatic symptoms

Prostate cancer can invade the bladder, seminal vesicles, and vascular nerve bundles, causing hematuria, semen, and impotence. Pelvic lymph node metastasis can cause edema in both lower limbs. Prostate cancer is often prone to bone metastasis, causing bone pain or pathological fractures, paraplegia. Prostate cancer can also invade the bone marrow, causing anemia or reduced whole blood count.

Diagnosis

Clinical diagnosis of prostate cancer mainly relies on digital rectal examination, serum PSA, transrectal prostate ultrasound, and pelvic MRI. CT is less sensitive than MRI in the diagnosis of early prostate cancer. Due to the high rate of bone metastasis in prostate cancer, a radionuclide bone scan is usually required before deciding on a treatment plan. Diagnosis of prostate cancer requires pathological examination through prostate biopsy.

The degree of malignancy of prostate cancer can be evaluated by histological grading. The most commonly used is the Gleason scoring system, which divides the degree of malignancy of prostate cancer into 2 to 10 points based on the sum of the scores of the primary and secondary structural areas in prostate cancer tissue. The best differentiated prostate cancer is 1+1=2 points, and the worst differentiated prostate cancer is 5+5=10 points.

Treatment

Radical treatment can be used for patients with early prostate cancer. The methods that can cure early prostate cancer include radioactive particle implantation, radical prostatectomy, and radical external radiation therapy.

The indications for radioactive particle implantation should meet the following three conditions: ① PSA<10ng/ml; ② Gleason score is 2-6; ③ The clinical stage is T1 to T2a.

The indications for radical prostatectomy should meet the following four conditions: ① PSA<10-20 ng/ml; ② Gleason score ≤ 7; ③ Clinical staging T1 to T2c; ④ Patients with a life expectancy of ≥ 10 years.

Radical radiotherapy is suitable for patients with localized prostate cancer. Three dimensional conformal radiotherapy and intensity modulated conformal radiotherapy are mainly used. In addition, external radiation therapy can also be used as an adjuvant treatment for patients with pathological changes such as pT3 to 4, seminal vesicle invasion, positive surgical margins, or persistent postoperative PSA elevation after radical prostatectomy; It can also be used for palliative treatment of patients with advanced or metastatic prostate cancer.

For patients with medium-term prostate cancer, comprehensive treatment methods should be adopted, such as surgery+radiotherapy, endocrine therapy+radiotherapy, etc.

Endocrine therapy is mainly used in patients with hormone sensitive advanced prostate cancer. The methods of endocrine therapy include castration (surgical or medical castration), anti androgen therapy (bicalutamide or flutamide), or castration+anti androgen therapy. The curative effects of surgical or medical castration are basically the same. But almost all patients eventually develop hormone independent prostate cancer or hormone resistant prostate cancer. Patients with castrated resistant prostate cancer can receive second-line endocrine therapy or new endocrine therapy drugs (Abiterone, enzalutamide, etc.). Patients with hormone resistant prostate cancer should continue to maintain castrated status and receive chemotherapy based on docetaxel and mitoxantrone. Prostate cancer patients with bone metastases should be treated with bone protectors (mainly bisphosphonates) to prevent and reduce bone related events, alleviate bone pain, improve quality of life, and improve survival. External radiation therapy or radionuclides can also improve local bone pain.

According to research in the United States, using PSA to screen for prostate cancer has the problem of over diagnosis and over treatment. In order to improve this situation, the "Clinical Practice Guidelines for Prostate Cancer" developed by the National Comprehensive Cancer Network of the United States in 2010 first included close observation rather than "active treatment" as one of the options for patients diagnosed with prostate cancer through prostate biopsy. The doctor is required to fully explain to the patient the dangers of close follow-up and the dangers of overtreatment, and the patient makes a decision. The basic conditions for strict follow-up of patients are: ① patients with low risk prostate cancer (T1 to T2a stage tumors, Gleason score of 2 to 6, PSA<10ng/ml, and life expectancy of less than 10 years; ② patients with extremely low risk prostate cancer (T1a tumor, Gleason score ≤ 6 points, PSA<10 ng/ml, biopsy<3 needle positive, cancer tissue per needle ≤ 50%, PSA density<0.15 ng/ml · g. Patients with a life expectancy of less than 20 years. The rigorous observation plan is to check PSA every 6 months, and perform rectal digital examination every 12 months. After the first prostate biopsy, especially for patients with a first biopsy ≥ 10 needle positive, puncture biopsy should be performed again within 18 months. In addition Repeat needle biopsies are performed on patients with low risk and life expectancy greater than 10 years, with a frequency of approximately once every 12 months. During close observation, if there is a tendency to progress in the disease, appropriate treatment measures should be taken.

Prevention

Research has shown that tomatoes and other foods containing lycopene may be effective in preventing prostate cancer. Two large-scale prostate cancer prevention trials have shown that the use of finasteride or dutasteride (a drug used to treat prostate hyperplasia) can reduce the incidence of prostate cancer by 25%, but may increase the risk of developing high-grade prostate cancer.