Several types of radiation therapy for prostate cancer are available. Traditionally, radical prostatectomy has been considered the gold standard of treatment for prostate cancer; but we now have excellent long-term outcomes with external beam radiation therapy as well. For men with tumors that have advanced beyond the wall of the prostate, radiation therapy is the standard treatment approach.3
There are two types of approach for radiation therapy. The external approaches involve sending radiation into the tumor from the outside with external-beam therapy. The internal approach is done via implantation of radioactive "seeds" directly into the tumor, which is called interstitial radiotherapy, brachytherapy, or simply, seed implantation.3(p317)
External Beam Radiation Therapy (EBRT)
Three dimensional conformal radiation therapy (3-DCRT)
3-DCRT is the first generation (developed in the 1990's) of radiation delivery. The patient first has a CT scan to determine radiation treatment design. The use of CT scanning to plan treatment provided a more precise view of the location, shape and surrounding area of the prostate. This happened conjointly with the development of faster computers, intricate software and imaging systems that allow more complex dose calculations and treatment planning. Physicians can custom-design a treatment so each patient's prostate tumor will receive the most precise and thorough radiation possible.
Intensity-modulated radiation therapy (IMRT)
Taking advantage of still more powerful computers and even newer radiation technology, the second generation of therapy, IMRT, creates a more sophisticated treatment. Instead of using four beams to treat the prostate, it uses multiple "beamlets"—sometimes hundreds—generated at multiple angles to "paint" the radiation dose to the prostate while avoiding surrounding tissues, especially the rectum. This allows the machine to sculpt the beam, molding it to fit the individual contours of each man's prostate and pelvic region.3
Proton-Beam Radiation Therapy
Proton-beam radiation therapy is a unique type of radiation treatment that uses charged particles instead of electromagnetic waves. The difference here is that the proton beam shoots in a straight line, but it penetrates through tissue with very little effect until it reaches a pre-determined distance, at which point it suddenly "detonates" and discharges all of its tumor-killing energy.3 This allows the tumor to be treated maximally while minimizing side effects by avoiding the surrounding normal tissue.
Image-guided radiation therapy (IGRT)
IGRT is one of the newest advances. The prostate changes position with an individual's movements and breathing. IGRT checks the position of the prostate on a particular treatment day and throughout the dose delivery. The resulting treatment ensures that the entire prostate receives the maximum radiation dose while damage to the normal tissues is avoided.
Advantages:
- Not invasive
- May cure prostate cancer in early stages
- Advantage for older men with other health problems that might preclude surgery
- Performed on outpatient basis
- Incontinence and impotence are less common than with surgery
- No anesthesia or transfusion risks
Disadvantages:
- Fatigue
- Skin reaction in treated areas
- Urinary frequency
- Dysuria
- Proctitis (inflammation of the rectum)
- Rectal bleeding
- Frequent stools
- Bowel urgency
- Abnormal bowel function
- Hematuria
- Rarely there can be a fistula
- No lymph node analysis or pathologic staging (Gleason score to determine Grade of tumor)
- Requires treatments five days a week for six to seven weeks
- 30-50% chance of erectile dysfunction
- 10-15% chance of bladder and or rectal irritation
- May cause hair loss in the area receiving the full dose (pubic hair)
- PSA doesn't decline to undetectable levels1
Second-line Treatment Option:
Hormone treatment, which is palliative (symptom-reducing rather than a cure). Salvage prostatectomy (removal of the prostate gland) with associated increased risk of incontinence.1 Prostatectomy is difficult to perform and rarely done after radiation therapy to the prostate.
Internal Radiation Therapy:
Interstitial Brachytherapy (Implanting Radioactive Seeds)
This procedure is gaining in popularity due to its minimal invasiveness and the fact that it requires a single treatment. Similar to radical prostatectomy, it is a procedure with intent to cure. The procedure involves the percutaneous (through the skin) placement of radioactive seeds into the prostate.1
Due to the multifocal nature of prostate cancer treatment, EBRT and interstitial seeds may be used together. Walsh compares brachytherapy to "implanting tiny sources of radiation directly into the cancerous tissue for hand-to-hand combat instead of launching missiles from a distance." Brachytherapy is not done via a free-handed surgical technique as in the past, but rather a sophisticated system that utilizes ultrasound and CT-guided systems. A template is used for direction of seed placement through the perineum. Doctors have become highly skilled at placing these seeds which are about the size of a grain of rice. They also carefully monitor the dosage of radiation that is delivered.
Advantages:
- Minimally invasive, quick recovery time
- Outpatient procedure
- No blood transfusions
- Suited for men with low grade tumors (smaller, Gleason score of 7 or less)1
Disadvantages:
- Not for men who have had previous TURP (transurethral resection of the prostate)
- Can't be done for larger glands (above 60 gm) unless hormone therapy can be used to shrink the gland prior to the procedure
- Urinary frequency, urgency or urinary retention
- Hematuria
- Rectal irritation, pain, burning, frequency and urgency with bowel movements
- Chance of impotence (25 to 60%) or painful ejaculation
- Impotence rate is lower initially but worsens over time
- No pathologic staging (Gleason Score) done1
Second-line Treatment Options:
- Salvage prostatectomy if localized (meaning the prostate is removed if the tumor is not outside the margins of the gland)
- Hormone treatment (ADT) if distant disease detected
References:
- Ellsworth P. 100 Questions & Answers About Prostate Cancer.2nd ed. Sudbury, MA: Jones and Bartlett Publishers; 2009.
- American Cancer Society, Bostwick D, Crawford ED, Higano C, Roach M, eds. Complete Guide to .Atlanta, GA: ACS Health Promotions; 2005.Prostate Cancer
- Walsh PC, Worthington JF. Dr Patrick Walsh's Guide to Surviving Prostate Cancer" 2nd ed. New York, NY: Wellness Central; 2007.
- Scholz, M. Newly Diagnosed Prostate Cancer: Evaluating The Options -- Part 2 Of 3. CRI Insights [online] August 2003 vol. 6, no. 3, Available at: http://www.prostate-cancer.org/pcricms/node/141#ADT. Accessed on September 11, 2010.
- Vogelzang, 2010 American Society of clinical Oncology Annual Meeting. August 2010 article: Cabazitaxel New Chemo Approved for Advanced Prostate Cancer. Available at: http://www.ustoo.org/PDFs/HotSheets/HotSheet082010.pdf . Accessed on September 11, 2010.
- Warde, 2010 American Society of clinical Oncology Annual Meeting. July 2010 article: RT Shown Beneficial for Prostate Cancer Subset. Available at: http://www.ustoo.org/Hot_Sheets.asp. Accessed on September 11, 2010.
- Crouzet, 2010 American Urological Association Annual Meeting Retrieved from July 2010 article: High Intensity Focused Ultrasound Noninferior to External Beam RT for Prostate Cancer. Available at: http://www.ustoo.org/Hot_Sheets.asp. Accessed on September 11, 2010.
- MSNBC. FDA approves new drug for prostate cancer (press release). Available at: http://www.msnbc.msn.com/id/36853649/ns/health-cancer/. Accessed September 14, 2010.
This article has been reviewed by a member of the Wellness Partners Editorial Board.
Posted September 2010
