Pathophysiology of prostate cancer
Prostate cancer is the most widespread cancer found in males second only to lung and bronchial cancer. In most cases, by the time the cancer is detected, the patient is past the stages where any treatment of the condition is possible. It means that by the time the cancer is detected, the patient would have very little time left. Till recently there was no means to detect the cancer at an earlier stage. Some years back Prostate Specific Antigen (PSA) came to be in scene.
The screening of the PSA became a practice in men over the age of 40 years. Any abnormality of the PSA should raise the eyebrows and more investigations should be initiated. Once PSA screening became a common practice and more and more men started coming forward for the screening to be conducted, in many cases the prostate cancer was detected at an earlier stage where some treatment could be done. This increased the survival rate of the patients.
In men over the age of 40 years, digital rectal examination at the time of annual physical examination is also important. While the digital rectal examination is done, if there is any abnormality of the prostate is detected, PSA screening should be considered. Further investigation or management should depend on the level of PSA. Education of the public regarding the causes, signs and symptoms and the warning signals of prostate cancer is as important as PSA screening so as to reduce the mortality in prostate cancer.
PSA is a glycoprotein which helps in liquefying semen. The upper normal level of PSA is 4ng/ml. While the PSA screening is done, every increase in the PSA level may not a signal of prostate cancer as increased PSA levels are also seen in benign prostate hyperplasia (BPH). Benign prostate hyperplasia is a condition where there is hyperplasia and enlargement of prostate but the condition is not malignant as in prostate cancer. So once the PSA level is seen to be higher than normal in a patient, free to bound PSA level is measures to see the ratio. If the ratio of free to total PSA level is low, more investigations are initiated as the condition is considered malignant. Free to total PSA level of over 25% is considered malignant and treatment for prostate cancer is started.
Pathophysiology:
Cancer occurs because of the abnormal division of malignant cells. The malignant cells divide and increase at a rapid rate where as the rate of death of these cells is normal which becomes very low. This results in an imbalance in the number of the abnormal cells in the organ and there by cancer grows rapidly. Once the abnormal rate has set in, gene mutations also would take place which would again result in the increase in the number of abnormal cells. As a result of all this, the cancer progresses very quickly and if treatment is not initiated at an earlier stage, this process would continue.
The cancer may happen at any part of the organ. In prostate cancer, most of the cancers originate in the peripheral zone, followed by the central and the transitional zone. This is generally the case, but the cancer may be multi-focal also, appearing at different regions of the prostate at the same time. Once the process of cancer sets in, it spreads from one region to another, and as the cancer progresses, it spreads to the bladder neck, ejaculatory duct and the seminal vesicles. This spread to urinary bladder and seminal vesicles are called local invasion of the cancer.
The cancer when limited to the prostate or even while in the locally invasive stage would have better chances of management. But once the cancer progresses to other parts of the body, management becomes difficult. The process of spread of cancer from the organ of origin to distant organs like liver or lung or bone is called metastasis. In many cancers, the metastasis would involve lymphadenopathy but prostate cancer may also occur without lymphadenopathy.
The first site of metastasis of prostate cancer is bone in many cases. And the metastasis in the bone would cause terrible pain to the patient.
There are several theories regarding the metastasis in prostate cancer. Soil and seed theory suggests that some factors already existing in the human body supports the spread of cancer cells to a distant organ and once a cancer cell reaches a distant organ it gets implanted there and spreads from there. There are evidences that certain organs like liver, lung, bone etc have increased incidence of metastasis in prostate cancer which is supportive of this theory. There is another theory stating that the metastasis of prostate cancer is mechanical. It is suggested in this theory that the spread of the cancer cells is through the lymphatic and venous spaces. The lower spine gets involved first where from it spreads to all the organs of the body.
Cancer of prostate could be adenocarcinomas which are the most common cell morphology but it is not always necessary. The cells can have neuroendocrine cell morphology also. In most of the cases the progression of the cancer is still not known. Also it has been seen that if treatment is initiated at an earlier stage where the tumor is small, the progression of the cancer slows down but as the tumor becomes bigger, the progress of the cancer also becomes faster. This is also one factor which should stress the importance of an early management of the prostate cancer.
It has always been seen that the patient may come to the physician not for management of cancer but with a lot of other symptoms and cancer of prostate is detected incidentally while the patient is undergoing investigations for the symptoms. The common signs and symptoms of prostate cancer include lower extremity pain, urinary retention, hematuria, frequency, decreased urinary stream etc. these are common symptoms in other conditions also like urinary tract infection or benign prostate hyperplasia. PSA screening is to be done to rule out other conditions and if the PSA levels are abnormal more investigations need to be done.
In cases of metastasis, weight loss, loss of appetite, intolerable pain, and pathologic fracture may be identified. And the individual, aware of the facts and symptoms would be able to identify the symptoms if any, and would be able to consult the physician at the earliest.
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