Prostate Cancer

The prostate is an organ that is located beneath the bladder and surrounds the urethra. Attached to the prostate are the seminal vesicles.

The purpose of the prostate is liquify the solution that protects and carries the sperm during ejaculation. Without the prostate, sexual reproduction would not be possible. In Greek, the word prostate means “protector of the family.” In this case, the prostate organ is the protector sexual reproductive organs (i.e. the penis, testicles, seminal vesicles, etc…).

The prostate is made up of 4 types of tissues:

glandular cells–responsible for liquifying semen
stromal cells–responsible for the structure
smooth muscle cells–responsible for squeezing and contracting glandular fluid
capsule–a dense fibrous membrane covering the prostate.
The size of the prostate is the size of a pea during early male development. At the beggining of puberty, the prostate will grow and stabilize in size to roughly the size of walnut.

In some cases, the prostate may enlarge and grow to the size of a grapefruit. This condition is abnormal and is called benign prostatic hyperplasia (BPH). Although BPH is not a cancerous condition, it must be treated. Common symptoms of BPH include the following:

the frequent need to urinate during the day or night
a weak urinary stream
a full-bladder feeling
difficulty initating a urine stream
a sudden urgency to urinate
a burning sensation during urination
loss of sexual potency
blood in the urine
urinary retention (unable to urinate)
BPH is treated with different methods which include, but is not limited to:

oral medications (alpha-blockers: tamulosin (Flomax or Omnic) 0.4 mg per day, terazosin (Hytrin) 2 – 10 mg per day, and doxazosin (Cardura) 2 – 8 mg per day)
trans-urethral prostatectomy (TURP)
surgical prostatectomy
laser prostatectomy
Risk Factors
Being at risk for prostate cancer is associated with men who are older (> 70 years), men who have a family history of prostate cancer, or men who are of African-American descent.

Additional risk factors, although evidence is inconclusive, are hormones, chemical exposures, geography, and deitary fat. There is no correlation between prostate cancer and men with vesectomy, men with high sexual activity, or men who smoke. Prostate cancer is seen less in Asian-American and Hispanic men.

Prevention
Up to date, there are no known prevention for prostate cancer. Although the evidence is thin, there may be some link between dietary fat consumption and prostate cancer.

Vitamin A from animal sources potentially increases the risk for prostate cancer. However, diet high Vitamin A from plant sources may potentially decrease the risk for prostate cancer.

Other molecules that may decrease the risk for prostate cancer includes isoflavonoids (plant-based weak estrogen found in soy products), lycopenes (carotenoid antioxidant found in tomatoes), selenium (seafood, meats, grains), and Vitamin E (vegetable and seed oil, whole grains, wheat germ, green leafy vegetables).

Symptoms
Men with prostate cancer may experience the following symptoms:
frequency of urination
difficulty in urination
diminished and interrupted flow
blood in the urine or sperm
Not all men with these symptoms have prostate cancer. Other benign conditions may have the same symptoms (i.e. BPH).

The patient should have a digital rectal examination by his physician or urologist and a routine blood test for prostatic specific antigen (PSA). If the rectal exam results in a suspicion for cancer and/or the PSA is elevated, the patient should undergo an ultrasound examination and biopsy of the prostate.

Screening and Diagnosis
Screening of prostate cancer is usually performed with a digital rectal examination (DRE) and prostate-specific antigen (PSA) test.

A DRE is recommend in all men over 50 years, or in men at high risk (those with a family history of prostate cancer or are of African-American descent) over 40 years. A negative DRE (a DRE that does not detect prostate cancer) does not exclude the presence of cancer, while a postive DRE is an indication to proceed with biopsy of the prostate.

PSA is a molecule produced exclusively by the prostate (cancerous or normal). PSA is used for both the detection of prostate cancer and response to treatment. The theory is that a prostate with cancerous prostate cells should show more production of PSA than a normal prostate.

A normal PSA is considered to be below 4.0 ng/mL. A PSA above 4.0 ng/mL may not indicate the presence of cancer, as BPH may also cause an elevation of PSA (between 4.0 – 10.0 ng/mL). Patients whose PSA is less than 4.0 ng/mL but increases by more than 0.9% within a year are recommended to undergo biopsy of the prostate.

A positive DRE and/or PSA test will warrant a biopsy of the prostate. Only a biopsy will conclusively verify the presence of cancer. A biopsy is usually performed by the urologist, radiologist, or radiation oncologist under transrectal ultrasound-guided method and local anesthesia.

During a biopsy, a needle is inserted through the rectum in the prostate and multiple core biopsies are obtained from the right and left peripheral zone from apex, mid gland, base, and intermediate zone. A minimum of 10 core biopsies are obtained. A negative biopsy will not exclude the presence of prostate cancer and repeat biopsy under IV sedation should be considered with more aggressive sampling when suspicion of prostate cancer is present.

A biopsy may also include the seminal vesicles since as much as 13% to 35% of all prostate cancer may involve the seminal vesicles.

Treatment Options
There are many treatment options for prostate cancer. Depending on patient preferences and other factors involved (i.e. contraindications that may prevent a patient from undergoing a certain treatment option), the patient may select from the following:

Watchful waiting–This treatment monitors prostate cancer with DRE, PSA test, or biopsy at regular intervals. This treatment option is appropriate for (ideally low-risk patients) men with early-stage prostate cancer (T1a,b,c or T2a), PSA < 10 ng/mL, and Gleason <= 6. The advantage of watchful waiting is to avoid the side effects of surgery, radiation therapy and hormone therapy.

Surgery– Surgery is the procedure of removing the entire prostate gland and surrounding tissues. Prostatectomy refers to the removal of the prostate and seminal vesicles. Radical prostatectomy refers to the removal of the prostate, seminal vesicles and pelvic lymph nodes. The approach to surgery may be retropubic or perineal. In retropubic surgery, a 6 inch incision is made below the belly button to remove the prostate gland. In the perineal approach, the prostate gland is removed through an incision between anus and scrotum (this area is called the perineum).

Hormone therapy– The goal of hormone therapy is to deprive the patient of androgen (male hormones), the most common of which is testosterone. Treatment of prostate cancer with hormones alone should not be used as a primary treatment for prostate cancer. Hormones are often used in addition and prior to the start of surgery or radiation therapy. When hormone therapy is given before surgery or radiation therapy, this practice is called neoadjuvant hormonal therapy. When hormone therapy is given after surgery, radiation therapy, brachytherapy, etc., because of failure and local or distant metastasis, this practice is called adjuvant therapy. The use of hormone treatment with radiation therapy is called combined treatment.

Cryotherapy– Cryotherapy destroys cancerous cells by freezing them, and is performed with the guidance of ultrasound through the perineum. The needle probes used in cryotherapy deliver argon gas or liquid nitrogen to the target area freezing the tissue into small ice balls, which are then thawed killing the cells and leaving scar tissue behind. There is minimal pain involved, and time is required for the killed tissue to pass. Patients are catheterized from weeks to months. Impotence is 100% for patients who undergo cryotherapy, and incontinence may occur. Cryotherapy is a relatively new treatment option for prostate cancer, and very few published papers are available.

External-beam radiation therapy (EBRT)– All patients with localized prostate cancer, including those with regional lymph node metastasis, are treated with external-beam radiation therapy (EBRT). In the last few years, the dosage of EBRT has increased from 65 to 80 Gy as a result of improvement in radiation technology and dosimetry-especially with intensity-modulated radiotherapy (IMRT). EBRT may not be sufficient to kill all the cancerous cells. Although prostate cancer is radio-resistant, it is curable with high doses of radiation. Higher doses of radiation with EBRT cannot be delivered due radiation injury to the adjacent urinary bladder and rectum. Furthermore, large volume prostate (> 60 cm3 ) or prostate cancer with seminal vesicle invasion requires a large field of radiation and may exceed radiation tolerance of the bladder or bowels. To overcome the limitations of EBRT in delivering high doses of radiation, interstitial radiation therapy (brachytherapy) with iodine 125 was introduced in 1970.