PROSTATE CANCER

What is it?

Prostate cancer (PC) is the leading tumor among male patients aged more than 50 years old. As medicine progresses, as well as other areas involved with healthcare, it is expected for the next decades an increasingly larger male population much older than that age cohort. It can be concluded, therefore, that more cases of PC will be diagnosed. Currently, there exist various campaigns for the early detection of this prostate neoplasia (cancer).

Early diagnosis is critical, since this is a curable cancer in its early stages.

How does it develop?

The prostate is a gland located near the bladder, surrounding the urethra in its initial portion. The prostatic secretions are the largest component of the seminal fluid (or sperm)

The origin of PC is unknown; however, some factors may presumably influence its development. Among them:

The genetic factor, since the incidence of this neoplasia is higher in family members suffering from the disease. The presence of PC in first-degree family members increases the probability of diagnosis for this cancer in 18%.

Hormonal factor is fairly important, since this neoplasia regresses significantly by inhibiting male hormones (i.g., castration). Researches conducted in mice, chronicaly treated with testosterone, showed the development of PC in these animals. Testosterone is not itself a cancer inducer; however, in men already diagnosed with, or predisposed to, the neoplasia, the testosterone would stimulate its development. On the other hand, PC does not occur in eunuchs.

Lately, the diet factor has been overly emphasized. Fat-rich diets predispose to cancer, while fiber-rich and tomato-rich diets lessen the odds of its developing. Based on epidemiological surveys in geographical areas of increased PC incidence, it was observed that fat-rich diets increase the risk of it developing. Perhaps due to interference with the metabolism of sex hormones various other substances are under investigation, such as vitamins, cadmium, zinc.

While herpesvirus type II and cytomegalovirus induce carcinogenetic transformations of hamster embryo cells (small lab-testing animal), venereal diseases are not associated with PC. The environment factor is also under investigation. Populations from low PC incidence areas migrating to high incidence areas present an increase in the occurrence of cases. Car exhaust smoke, cigarettes, fertilizers and other chemical products are under suspicion.

What does one feel?

There are no symptoms in the early stages. The tumor is only detected through routine clinical and laboratory tests, namely: digital rectal exam Prostate-specific antigen (PSA)

In cases of symptomatic PC, patients report having difficulty initiating urination, weak urine stream, sensation that the bladder does not feel completely empty, that is, symptoms of urinary obstruction. Although rarer, blood in the urine may also be reported.

The patient may experience bone pain as an indication of a more advanced disease (metastasis)

Anemia, weight loss, adenopathy (limph nodes) in the neck and inguinal region may also be a first manifestation of the disease.

Every man, beginning at age 45, should undergo screening for prostate cancer, which is performed using PSA blood test and the digital rectal exam, especially those with a family history of PC (and breast cancer), regardless of the symptoms. In case of abnormal rectal exam or high PSA levels, the patient should undergo a transrectal ultrasound-guided prostate biopsy. The tissue removed will be taken to the anatomopathologic examination. Once the diagnosis is confirmed, the tumor should be clinically staged. This means that additional tests should will be required so as to ascertain whether the tumor is confined to the prostate or has it invaded the surrounding organs (bladder, seminal vesicle, rectum), or has it already sent metastases. Bone scintingraphy is the most valuable test at this stage, providing information as to the metastases throughout the skeletal system. Other tests occasionally required are: alkaline phosphatase, abdominal computed tomography, chest and skeletal radiographs.

How is it treated?

PC may be confined to the prostate under a nodular form, as well as be restricted to it though involving the whole gland. In addition to being localized, PC may be compromising the boundaries of this organ by invading other surrounding organs, such as the seminal vesicles or the bladder. Obturator and iliac lymph nodes are, in general, the first stage of the metastases, then the bone metastases occur.

There are several classifications (the Whitmore, TNM ) in order to describe the extent of the tumor (clinical staging). In addition to the tumor extent, it is important to know that PC presents a cell differentiation, more or less malignant, which are is also graded through a classification method (Gleason grading system).

Therefore, the type of treatament is chosen based on the turmor staging and its classification on the Gleason grade.

For tumors localized inside the gland, the radical prostatectomy and radiotherapy are the first- choice treatments considered to be curative.

Extraprostatic tumor extensions without evidence of metastases are generally treated with radiotherapy.

Female hormones, orchiectomy, anti-androgenic drugs or LHRH (luteinising hormone releasing hormone) analogues are used to control metastatic tumors palliatively.

PC treatament has proven very controversial, since there many variables to involved.
 

Patient age
PSA levels
tumor stage
histological type

Additionally, the complications of the treatment should be discussed with the patient.

Both radical prostatectomy and radiotherapy may cause the patient to become impotent as well as urine-incontinent.

Hormone therapy diminishes libido and causes sexual impotence.

Patient's age at the time of the diagnosis and his life expectancy without the disease should also be taken into consideration. Very elderly patients with low life expectancy will certainly benefit from less aggressive treatments. Psychologic and cultural problems make the orchiectomy (testicles removal) an undesired treatment. Other forms of therapy have not proved successful or are under investigation, as is the case with chemotherapy, genetic therapy and growth factors.

Which is the prognosis?

The prognosis depends, especially, on the staging (extent) and histologic degree (Gleason). If PC is localized and if the patient undergoes a radical prostatectomy, life expectancy in 10 years may be as high as 90%, which is the equivalent to the standard population. The local recurrence rate after 5 years is 10%, against 40% with radiotherapy. The radiotherapy used in localized PC or locally advanced (outside the prostate but nonmetastatic) presents positive biopsies of 60% to 30% of cases when performed six months and two years posttreatment, respectively. In metastatic cases, the treatament is palliative and the prognosis is far more pessimistic.

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