Testosterone profoundly affects the development of prostate cancer. Prostate cancer does not occur in eunuchs. There is an increased incidence of prostate cancer amongst relatives of patients with prostate cancer and in Afro-American men. A high-fat diet may also predispose towards prostate cancer.
Prostate-Specific Antigen (PSA)
This is a tumor marker with normal values between 0 and 4 ng/ml in young adults. Low-grade prostate cancers produce more PSA than high-grade prostate cancers. An elevated PSA may occur with prostate cancer or an enlarged prostate, or after a urinary tract infection. The PSA can be used in several ways:
(a) Age-specific PSA, where there is a marginal increase in PSA with age;
(b) PSA density (serum PSA/prostate volume);
(c) Free PSA, which is associated with BPH and not cancer; and
(d) Complex PSA, which may be more specific for those with prostate cancer.
A transrectal ultrasound (TRUS) and needle biopsy will provide histological evidence of whether or not the elevated PSA is caused by a prostate cancer or because of benign disease. A TRUS on its own without the needle biopsy for histological examination is worthless. The only value of the ultrasound study on the prostate is to estimate its size and also to know that the needle has passed into the prostate.
Treatment of Localized Prostate Cancer
A. RADICAL PROSTATECTOMY AND REGIONAL LYMPHADENECTOMY.
The standard technique is a retropubic approach, although others have recommended laparoscopic lymph node dissection and a perineal approach. This may be the preferred approach for very obese individuals.
B. RADIATION THERAPY.
1. External beam. Patients are treated at a rate of 200 rads per day up to a total of 6800-7600 rads for a total treatment duration of 6-7 weeks. Newer conformal techniques enhance our ability to deliver higher radiation doses to the prostate without affecting adjacent organs.
2. Interstitial radiation/brachytherapy. New methodology, including the use of palladium seeds and iodine implants, suggest that this technique may produce a favorable outcome. In addition, the radiation can be supplied in one outpatient setting under a general anesthetic.
C. CRYOABLATION.
Cryoablation Surgery |
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Cryoablation of the prostate may be used to treat localized prostate cancer or recurrences after previous radiation treatment. Cryoablation of the prostate may be done either through total freezing of the prostate or through focal or regional freezing to treat only the involved section of the prostate. In this manner the nerves for erection sitting on the uninvolved part of the prostate may remain intact to preserve erections.
The surgery is done by inserting 6-8 slender probes into the prostate under transrectal ultrasound control. Argon gas is circulated through the probes to freeze the prostate while helium is used to warm it. Two freeze thaw cycles are usually performed in the treatment process.
Several temperature sensors carefully monitor the process to determine that target freezing temperatures are reached while adjacent areas such as the sphincter and rectum are protected. A warming catheter protects the urethra from very cold temperatures.
This surgery is usually performed as an outpatient and commonly you will have a foley catheter draining your bladder for about a week. The cryoablation procedure can also be performed focally in that only the involved lobe of the prostate is treated and therefore minimizing the risk of impotence. This outpatient cryoablation procedure can also be repeated if the prostate cancer should recur.
D. HIGH INTENSITY FOCUSED ULTRASOUND (HiFu)
High intensity focused ultrasound can also be used to treat prostate cancer by using ultrasound wave energy focused on the prostate via a transrectal probe. This procedure can be performed under a spinal anesthesia in an outpatient setting. The catheter is removed in the office several days later. Recurrent prostate cancer can be treated using this modality.
(See International HiFu)
Complications
Surgeons may have to deal with immediate complications during or immediately after surgery. The long-term complications are incontinence and impotence. Techniques for apical dissection of the prostate and for bladder neck repair may help minimize the chance of incontinence while special attention to apical dissection for nerve-sparing may reduce the incidence of impotence.
If incontinence occurs, a procedure where a sling is placed inside the body to support the muscles surrounding the urethra, consequently promoting urinary control, can be performed. (See InVance Sling for more information.)
Radiation fibrosis of the neural and vascular pathways also may bring about impotence. Radiation cystitis and proctitis may occur, but incontinence is uncommon after radiation.
Positive Margins
40% to 70% of men undergoing radical prostatectomy who were believed on evaluation to have organ-confined cancer have extracapsular extension or positive margins at pathological examination. Postoperative adjuvant therapy such as irradiation with or without hormones may be helpful.
Pelvic Recurrence
About 1/5 of men who have had a radical prostatectomy will develop a pelvic recurrence after radical surgery, and these are usually treated with irradiation.
Treatment of Metastatic Prostate Cancer
Most prostate cancers are relatively hormone-sensitive, and treatment is designed to employ some pathway to the control of testosterone production.
A. Conservative management.
B. Hormonal therapy.
1. LH-RH agonists. Luteinizing releasing hormone LH-RH agents act by initially stimulating pituitary gonadotropin production and then inhibiting it. After 2-3 weeks of treatment, testosterone drops to castration levels. Examples of these agents are Lupron and Zoladex.
2. Anti-androgens. These agents act by competing with dihydro-testosterone for binding to the receptors for androgen synthesis. Examples of these agents include Casodex and Eulexin.
3. Combined androgen blockade. This is the use of combining an anti-androgen with an LH-RH analog or orchiectomy.
4. Orchiectomy. This is a very cost-effective form of androgen ablation for androgens of testicular origin by surgically excising the testicles.
C. Chemotherapy.
Several agents such as 5-Fluorouracil, Adriamycin, estramustine phosphate, cyclophosphamide and hydroxyurea have produced some marginal responses. There has been a resurgence in use of combined regimens, which may act synergistically and may achieve higher response rates.
Palliative Therapy
Strontium 89 is a pure beta radiation emitting compound, and when given systemically travels to metastatic bone involvement where there are areas of new bone activity. This agent may bring about significant relief of pain.