PROSTATE CANCER

موضوع: PROSTATE CANCER الإثنين مارس 25, 2019 6:24 pm

[size=34]PROSTATE CANCER[/size]

Introduction

Prostate cancer is the most frequently diagnosed cancer (excluding skin cancer) and the second leading cause of cancer death in American men. Only lung cancer results in more male cancer deaths in this country. Each year, roughly 180,000 men in the U.S. will be diagnosed with prostate cancer, and about 37,000 will die of this disease. These numbers are remarkably similar to those for breast cancer. However, there seems to be less awareness regarding prostate cancer, and breast cancer receives more research funding. In recent years, though, prostate cancer has been receiving more attention, as a number of public figures have been diagnosed and treated for it.

Risk Factors

The cause of prostate cancer is unknown, but several factors associated with a higher risk for it have been identified.
Increasing age is one of the most closely associated variables, with the average age at diagnosis being 72. Fewer than 10 percent of cases are diagnosed in men less than 60 years of age, and more than 75 percent of cases are diagnosed in men older than 65.
The incidence of prostate cancer is low in native Chinese and Japanese men but higher among men from Scandinavian countries.
African American men have the highest incidence rate of prostate cancer in the world, and they also present with more advanced stages of disease and are more than twice as likely to die of prostate cancer than are white American men.
The incidence of prostate cancer is higher in men with a family history of prostate cancer, particularly in those with two or more first-degree relatives having the disease. Diets high in fat ******* may also increase the risk of developing prostate cancer. Of these risk factors, diet is the only one that, in theory, can be modified.

Symptoms

In most cases, prostate cancer itself causes no specific symptoms, especially in its early stages. It is sometimes diagnosed in men who present with symptoms of urinary obstruction related to benign enlargement of the prostate (benign prostatic hypertrophy, or BPH).
BPH is a separate, unrelated process and does not appear to cause prostate cancer. In rare instances, cancer can become advanced within the prostate and cause urinary obstructive symptoms, but these symptoms are much more often due to BPH. Occasionally, prostate cancer can spread to the bones and cause pain prior to diagnosis.

Screening

Since prostate cancer typically causes no symptoms in its earliest, most curable stages, individuals must be screened in order to detect prostate cancer in its early stages of development. Historically, this was accomplished with a digital rectal examination (DRE), in which the physician inserts a gloved finger into the rectum to feel for nodules, hard areas, asymmetry, and other abnormalities.
However, many of the abnormalities detected by DRE turn out not to represent prostate cancer, and, conversely, DRE fails to detect some prostate cancers.
A blood test known as PSA (prostate specific antigen) is more sensitive and frequently is elevated in patients with prostate cancer who have a normal DRE.
However, the PSA is sometimes normal in patients with prostate cancer, so both PSA and DRE should be performed in screening for prostate cancer. Whether widespread screening for prostate cancer should be recommended is controversial.
Men, particularly those above age 50, should discuss with their physician whether to undergo screening for prostate cancer. Those at higher risk, such as African Americans and those with a family history of prostate cancer, may wish to consider screening at age 40-45.

Diagnosis

A man with an abnormal PSA or DRE should be evaluated to determine the cause of the abnormality. PSA elevation may be due to prostate enlargement, inflammation or infection of the prostate, prostate cancer, or other causes.
A biopsy of the prostate gland is often necessary to determine the cause and to rule out the possibility of prostate cancer.
This is usually performed under transrectal ultrasound (TRUS) guidance, a procedure in which a urologist views images of the prostate obtained by inserting an ultrasound probe into the rectum. Needles are inserted through the probe and into the prostate to obtain tissue samples which are analyzed for the presence of prostate cancer.
This is usually a simple outpatient procedure. If prostate cancer is found in the biopsy specimens, additional tests, such as a CT scan or bone scan, may be ordered to determine whether the cancer has spread beyond the prostate gland. In some cases, additional testing is not necessary.

Prognostic Factors

Several variables can aid the physician in predicting the aggressiveness of a particular case of prostate cancer and, in turn, aid in deciding which form of treatment is most appropriate for each individual.

: These prognostic factors include
PSA, Gleason score, tumor stage, and lymph node status
Higher PSA levels at diagnosis predict a higher likelihood that the cancer will spread or relapse after treatment.
The Gleason score is a system in which a grade is assigned to the cancer, ****d on characteristics of the appearance of the tumor under the microscope. A higher grade or higher Gleason score also predicts a higher probability that the tumor will spread or recur after treatment. The stage of the tumor is a de******ion of the size or extent of the tumor, ****d of DRE, TRUS, and other measures. Higher stage tumors are more advanced and are less likely to be completely removed by surgery or eradicated by radiation treatment.
Conversely, cancers associated with a low PSA level, low Gleason score, and early stage are more likely to behave in an indolent fashion and are more likely to be controlled by surgery, radiation, or other treatments.

Treatment

Several options exist for management of prostate cancer. These include: surgery, radiation therapy, hormonal therapy, and observation (watchful waiting).
The decision regarding which treatment is best for an individual can be complex, and many factors influence this decision.
The optimal treatment in one case is often not the best choice in another case. Each method of treatment has advantages and disadvantages, and the challenge for physicians and patients is to determine the most appropriate course of action for each patient.

Surgery

Surgical treatment of prostate cancer usually consists of a radical prostatectomy – complete removal of the prostate. This has the potential to cure cancers in which the tumor is confined within the prostate gland.
Advantages of this procedure include its potential to cure early stage cancers, avoidance of potential problems associated with radiation, and accurate determination of the tumor’s extent, ****d on careful microscopic examination of the lymph nodes and prostate gland by a pathologist.
The pathologist’s findings can refine knowledge of the patient’s prognosis and may indicate the need for additional treatment, such as radiation therapy or hormonal therapy.

Disadvantages of radical prostatectomy include the fact that it is a major operation that requires hospitalization and that it may result in side effects such as impotence or incontinence.
Transurethral resection of the prostate (TURP) is a procedure in which tissue is removed from the inside of the prostate in order to relieve obstruction of urinary flow from the bladder.
Since it removes only part of the prostate gland, this operation is not designed to cure prostate cancer and is usually done to relieve symptoms related to BPH. It may sometimes be performed for symptom relief if prostate cancer is locally advanced and the patient is not a candidate for radical prostatectomy because of advanced age, medical problems, or advanced stage prostate cancer.

Radiation Therapy

Radiation therapy uses x-rays to kill prostate cancer cells. Like radical prostatectomy, it is capable of curing prostate cancer in its earlier stages.
Radiation is delivered by two general methods: external beam radiation therapy and interstitial brachytherapy.
External beam irradiation is delivered by a machine called a linear accelerator, which generates a high-energy x-ray beam that is aimed at the prostate gland from outside the body. The patient lies on a table, and the linear accelerator rotates around the table, typically delivering the beam from four or more directions, converging on the prostate gland.
Treatments are administered once a day, five days a week, for approximately eight weeds. Each treatment lasts a few minutes, and the patient feels nothing during treatment delivery. External beam radiation therapy may also be given to the prostate bed in patients in whom the cancer recurs there after surgery. Radiation therapy may also be used to treat pain and other problems in advanced cases in which the cancer spreads to the bones or other areas.

Recent advances in computer technology have given rise to more accurate methods of targeting and delivering the radiation beam – three-dimensional conformal radiation therapy (3D conformal radiation) and intensity modulated radiation therapy (IMRT).
Proton beam radiation therapy, available only in a few centers nationwide, is another means of delivering radiation more accurately.
These newer techniques all facilitate irradiation of the prostate gland while minimizing radiation exposure to surrounding structures such as the bladder and rectum.
Advantages of external beam radiation therapy include its potential to cure early stage prostate cancer, avoidance of major surgery, and a lower risk of incontinence and impotence than with radical prostatectomy. Disadvantages include extensive travel associated with the course of treatment and potential complications such as bowel damage.

Interstitial brachytherapy is a technique in which radioactive sources are placed into the prostate gland, delivering radiation from within the prostate.
The most common method of brachytherapy is known as the “seed implant,” in which multiple radioactive seeds, usually isotopes of iodine or palladium, are inserted into the prostate by needles passing through the **** of the scrotum under ultrasound guidance. Other methods of inserting the seeds have also been developed. The seeds remain in the **** permanently, although the radioactivity diminishes over time.

The seed implant may be performed as the sole treatment modality in very early stage prostate cancers of low aggressiveness, or it may be combined with an abbreviated (five-week) course of external beam radiation therapy, particularly in cases in which the PSA, Gleason score, or tumor stage would predict a lower likelihood of controlling the cancer with the seed implant alone.

In some cases, radioactive sources, typically an isotope of iridium, are inserted into the prostate gland temporarily and than removed. This is known in some situations as high-dose rate (HDR) brachytherapy and is usually combined with an abbreviated course of external beam irradiation. An advantage of combining external beam radiotherapy with the seed implant or HDR brachytherapy over external beam irradiation alone is that the former approach delivers a higher total radiation dose to the prostate and may result in a higher probability of controlling the cancer.
For patients who are suitable candidates for the seed implant alone, this approach is often attractive, as it avoids both the lengthy course of external beam radiotherapy and the major surgery associated with radical prostatectomy. Disadvantages of the seed implant include its relatively shorter track record than radical prostatectomy or external beam radiation therapy and the fact that it is a minor surgical procedure, which may not be suitable for some patients.

Hormonal Therapy

Prostate cancer’s development and growth is stimulated by testosterone, the male sex hormone. Thus, prostate cancer usually responds favorably to withdrawal of testosterone. In some cases, all clinical evidence of prostate cancer can disappear in response to hormonal therapy. However, hormonal therapy alone is not regarded capable of curing prostate cancer.
Hormonal therapy is usually recommended for patients who initially present with the cancer having spread to bones or lymph nodes, patients in whom the cancer spreads to such areas after surgery or radiation therapy, or patients in whom the cancer recurs after radiation therapy. Hormonal therapy may also be recommended for some patients with earlier stage prostate cancer who are not suitable for definitive surgery or radiotherapy.
Historically, hormonal therapy was usually accomplished by surgical removal of the testicles (orchiectomy) or administration of female hormones such as DES. DES is not commonly used today, since it may cause heart and blood vessel problems, breast enlargement, and other side effects. Newer pharmaceutical agents are usually better tolerated and do not require removal of the testicles, which men may find objectionable.
These agents include injections known as LHRH agonists, such as Lupron or Zoladex, and oral medications known as nonsteroidal antiandrogens, such as Eulexin or Casodex. Orchiectomy remains a simple, expedient option in some cases, though.

Temporary courses of an LHRH agonist, sometimes with an antiandrogen, are sometimes used in combination with radiation therapy. Recent studies have shown that this combination of therapies may result in better cancer control in some cases than radiation therapy alone.
A temporary course of hormonal therapy may also be used to shrink the prostate gland if the prostate is initially too large to permit interstitial brachytherapy.

Observation

Also known as watchful waiting, this is a choice not to undergo definitive treatment for prostate cancer, involving an assumption that an individual is likely to die of a cause other than prostate cancer. Prostate cancer sometimes progresses slowly, and the choice of no active treatment may be reasonable, particularly in an elderly patient or one with major medical problems.

For patients who are relatively young (less than approximately 70 years old) and otherwise reasonably healthy, physicians in this country are often hesitant to endorse a policy of watchful waiting.

Follow Up/Salvage

After definitive treatment with surgery or radiation therapy, patients are typically followed by their urologist and sometimes by other physicians.
The DRE and PSA are repeated at fairly regular intervals, usually a few times each year. Other tests may be ordered if necessary. A progressive rise in the PSA is frequently the earliest sign of relapse after surgery or radiotherapy.
Radiation therapy, sometimes in combination with hormonal therapy, may be instituted if the PSA rises after radical prostatectomy.
Hormonal therapy is usually initiated for a rising PSA after radiation therapy. Patients on hormonal therapy for advanced disease are followed by their urologist or other physicians.
If the disease progresses despite hormonal therapy, palliative radiation therapy, second-line hormonal therapy agents, chemotherapy, or other treatments may be indicated.
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موضوع: رد: PROSTATE CANCER الإثنين مارس 25, 2019 6:27 pm

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