Prostate

GX: Grade cannot be assessed G1: Well differentiated (slight anaplasia; Gleason 2-4) G2: Moderately differentiated (moderate anaplasia; Gleason 5-6) G3-G4: Poorly differentiated/Undifferentiated (marked anaplasia; Gleason 7-10) ||
 * **Epidemiolgy:** || Prostate cancer is very common. In fact, it is the most common form of malignancy in men in the United States. 1 The approximate number of men that will develop prostate cancer in their lifetime is 1 in 6. In 2008, about 186,320 men were diagnosed in the U.S. and 28,660 will die. As men get older, their risk of prostate cancer increases, with more than 65% of prostate cancers occuring after the age of 65. ||
 * **Etiology:** || The risk factors for prostate cancer include 1 :
 * Age (older have higher risk)
 * Race (African Americans have higher risk)
 * Family History
 * Diet ||
 * **Signs & Symptoms:** || * Trouble urinating
 * Blood in the urine
 * Blood in the semen
 * Swelling in the legs
 * Discomfort in the pelvic area
 * Bone pain 2 ||
 * * **Diagnostic Procedures:** || * Digital rectal exam (DRE). This examination helps to find abnormalities in the texture, shape or size of your prostate gland.
 * Prostate-specific antigen (PSA) test. PSA is a substance that's naturally produced by prostate gland. It's normal to find a small amount of PSA in a blood test. However, if a higher than normal level is found, it may be an indication of prostate infection, inflammation, enlargement or cancer.
 * Bone scan
 * Ultrasound
 * Computerized tomography (CT) scan
 * Magnetic resonance imaging (MRI) 2 ||
 * **Histology:** || Adenocarcinoma, arising from the peripheral acinar glands, is the most common tumor in the prostate. 3 ||
 * **Lymph node drainage:** || Prostate cancers spread through a lateral lymph pathway. 3 The first nodes involved are the obturator nodes and then the external iliac nodes. The second common drainage pathway is through the internal iliac path, this includes the junction of the internal and external iliac nodes. ||
 * **Metastatic spread:** || If prostate tumors can extend through the capsule of the gland and invade nearby tissues and seminal vesicles. 1 If they’re left untreated, they can involve the bladder neck or rectum. The tumor may invade the perineural spaces, lymphatics, and blood vessels, producing lymphatic or distant metastasis. ||
 * **Grading:** || Histologic Grade (G) 1 :
 * **Staging:** || Like other cancers, the staging of prostate cancer helps determine if the disease has spread to other areas of the body by direct invasion, lymphatic spread, or through the blood stream. At the time of diagnosis, several studies may have been performed which can help in the staging process. The most common studies done are rectal exam, prostate-specific antigen, transrectal ultrasound, MRI, CT, or surgery to examine lymph nodes. 4

The TNM System for Prostate Cancer Stages 4
As they do for most cancers, doctors use the TNM system of prostate cancer stages. The prostate cancer stages are described using three different aspects of tumor growth and spread. It’s called the TNM system for tumor, nodes, and metastasis:
 * T -- for tumor -- describes the size of the main area of prostate cancer.
 * N -- for nodes -- describes whether prostate cancer has spread to any lymph nodes and to what extent.
 * M -- for metastasis -- means distant spread of prostate cancer, for example, to the bones or liver.

Prostate Cancer Stage I
In stage I, prostate cancer is found in the prostate only. Stage I prostate cancer is microscopic; it can’t be felt on a digital rectal exam (DRE), and it isn’t seen on imaging of the prostate.

Prostate Cancer Stage II
In stage II, the tumor has grown inside the prostate but hasn’t extended beyond it.

Prostate Cancer Stage III
Stage III prostate cancer has spread outside the prostate, but only barely. Prostate cancer in stage III may involve nearby tissues, like the seminal vesicles.

Prostate Cancer Stage IV
In stage IV, the cancer has spread (metastasized) outside the prostate to other tissues. Stage IV prostate cancer commonly spreads to lymph nodes, the bones, liver, or lungs. Accurately identifying the prostate cancer stage is extremely important. Prostate cancer stage helps determine the optimal treatment, as well as prognosis. For this reason, it’s worth going through extensive testing to get the correct prostate cancer stage. 4

There are also other ways to classify prostate cancer. The Gleason system, which is determined by the pathologist to determine the grade of cancer, is often combined with the TNM system to describe prostate cancer. || A radical prostatectomy is often used as the entire prostate is removed as well as the seminal vesicles and some of the surrounding tissues. A transurethral resection of the prostate (TURP) is also used occasionally to remove small amounts of tissue within the prostate. A rectoscope is inserted into the urethra and up into the prostate for this procedure. Finally a pelvic lymphadenectomy to remove pelvic lymph nodes may be used if there is nearby extension. 6 Using a box field technique, arc fields, or intensity modulated radiation therapy (IMRT), a radiation therapy treatment is typically taken to a dose of 70-74 Gray (Gy). The inferior border sits directly below the ischial tuberosities while the lateral aspect extends 1-2 centimeters (cm) from the bony pelvis. Anteriorly a 1.5cm margin posterior to the pubic symphasis is used, and the posterior border should include the pelvic/presacral lymph nodes anywhere above the S-3 region. The dose is usually distributed 45 Gy in the original fields with a boost of 22-26 Gy to the prostate. If the radiation treatments are post-op, the dose to the nodes are taken to 45 Gy, and the prostate bed reaches 66 Gy. There is also a common use of interstitial implants for low risk prostate patients. There are two methods to completing prostate therapy, permanant implants such as iodine 125 or palladium 103, or temporary implants such as iridium 192. 3 In order to decrease androgenic simulation, and decrease recurrences, hormone therapy is often used. This can be achieved by suppressing the pituitary, inhibiting androgen synthesis, and interferring with the action in the androgenic tissues. Using drugs to prevent the growth of cancer cells, chemotherapy is a proven modality in many cancers. While it does not play a large role in prostate cancer, there are a few trials that have used it as a new method. Chemotherapy drugs such as docetaxel, mitoxantrone, prednisone, and dexamethasone all have been used as a part of these clinical trials. 6 In addition, cryosurgery, high intensity focused ultrosound, and proton beam radiation therapy are being used as potential treatments for prostate cancer. 6 || Bladder 6000 centigray (cGy) Rectum 6000 cGy Femoral Head 5200 cGy Cuada Equina 6000 cGy || Reprinted from //Treatment Planning in Radiation Oncology//, 3rd Edition. 5 The above axial computed tomography (CT) image shows a three-dimensional (3D) conformal radiation treatment plan utilizing a four-field technique.
 * **Radiation side effects:** || The most common side effects from radiation therapy to the prostate are 3 :
 * Gastrointestinal side effects such as loose stool, diarrhea, rectal discomfort, rectal bleeding
 * Genitourinary symptoms such as cystourethritis, dysuria, frequency changes, nocturia, or microscopic hematuria
 * Urinary tract infections
 * Erythema and dry or moist desquamation in the perineum or intergulteal fold
 * Leg, scrotal, or penile edema
 * Anal sphincter weakening or incontinence
 * Erectile dysfunction
 * Lumbosacral plexopathy ||
 * **Prognosis:** || While there are a variety of factors that determine a patient's prognosis such as Gleason score, age, and health, the tumor differentiation, prostate-specific antigen (PSA) level, and stage of the primary tumor are the best indicators. If a patient reports with an elevated PSA level after surgery, or irradiation, their disease is most likely going to be recurrent. Also, if the patient presents with a Gleason score higher than 7, the prognosis of the patient is poor. 3 ||
 * **Treatments:** || There are four main modalities that are used to treat prostate cancer. Surgery with radiation therapy is the most common, while chemotherapy and hormone therapy are also used for some patients.
 * Surgery:**
 * Radiation therapy:**
 * Hormone therapy:**
 * Chemotherapy:**
 * **TD 5/5:** || Organ TD 5/5 1 :
 * **Additional images:** || [[image:uwlmedicaldosimetry2013/figure_26.8.jpg width="560" height="366"]]

Reprinted from //Treatment Planning in Radiation Oncology//, 3rd Edition. 5 The above image is a typical dose-volume histogram (DVH) showing the bladder, rectum and planning target volume (PTV) from a 3D conformal radiation treatment plan.

Reprinted from //Treatment Planning in Radiation Oncology//, 3rd Edition. 5 2. Prostate cancer. MayoClinic Web site. http://www.mayoclinic.com/health/prostate-cancer/DS00043/DSECTION=tests-and-diagnosis. Accessed June 14, 2013. 3. Chao KS, Perez CA, Brady LW. // Radiation Oncology Managements Decisions //. 3rd ed. Philadelphia, PA: Lippincott William and Wilkins; 2011. 4. Zatzkin J. Stages of prostate cancer. WebMD Web site. http://www.webmd.com/prostate-cancer/guide/prostate-cancer-stages. 2011. Accessed June 14, 2013. 5. Khan FM, Gerbi BJ. // Treatment Planning in Radiation Oncology //. 3rd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2012. 6. Prostate cancer treatment. National Cancer Institute Web site. [|http://www.cancer.gov/cancertopics/pdq/treatment/prostate/healthprofessional/Page8#Section_2449]. Accessed June 19, 2013. || Back to Week 4
 * Image A: An axial CT image is shown from a seven-field intensity modulated radiation therapy (IMRT) plan.
 * Image B: The dose distribution is demonstrated using a dose “color-wash” and depicts the concave dose distribution achieved for the rectum. This results in the improved normal tissue DVH for the IMRT plan.
 * Image C: Four-field, 3D conformal treatment plan DVH for the same patient. ||
 * **References:** || 1. Washington CM, Leaver D. // Principles and Practice of Radiation Therapy // . 3rd ed. St. Louis, MO: Mosby Elsevier; 2010.