Understanding prostate cancer, lecture three, treatment of localized prostate cancer. At the end of this lecture, you will be able to number one, understand how and when active surveillance is used in localized prostate cancer. Number two, understand how and when radiation is used to treat localized prostate cancer. Number three, understand how and when surgery is used to treat localized prostrate cancer. And number four, understand what risk of recurrence means and how it applies to localized prostrate cancer treatment. Introduction to Prostrate Cancer Treatment. Cancer treatment comes in many forms. These include surgery, radiation, hormonal therapy, chemotherapy: which is not generally used in local treatment, targeted therapy: not generally used in local treatment, and immunotherapy: not generally used in local treatment. it is important to start with a fact. Approximately 50% of all people diagnosed with cancer in the United States are cured by surgery or radiation, because the cancer is removed or killed by radiation before it has spread. A cancer diagnosis is not a death sentence. Surgery and radiation provide the backbone for all cancer therapy. Surgery removes the tumor. Radiation can be given as external beam radiation or by implanting radioactive seeds into the tumor to kill the cancer cells. Therapies can be given in conjunction with surgery or radiation. A neoadjuvant therapy refers to a therapy, usually a chemotherapy or a hormonal therapy, given before surgery or radiation to the primary cancer. Adjuvant therapy is a therapy, usually a chemotherapy or a hormonal therapy, given after surgery or radiation to the primary cancer. These are common terms used in cancer treatment. Neoadjuvant treatment, before surgery or radiation. Adjuvant treatment, after surgery or radiation. The main surgical treatment for prostate cancer is radical retropubic prostatectomy. A prostatectomy is a surgical procedure for the removal of the prostate. It's performed to treat prostate cancer. The prostate, seminal vesicles, and lymph node near the prostate are removed. The term radical is used with surgery when the whole organ is removed. In the open approach, the surgeon takes the prostate out through an incision in the abdomen between the umbilicus, or belly button, and the pubic bone. In a laparoscopic approach, the surgeon makes several small cuts and long, thin tools are placed inside the cuts. The surgeon puts a thin tube with a video camera, a laparoscope, inside one of the cuts and instruments through the others. This helps the surgeon see inside during the procedure. Sometimes, laparoscopic surgery is done using a robotic system. The surgeon moves the robotic arm while sitting at a computer monitor near the operating table. This procedure requires special equipment and training. Not every hospital can do robotic surgery, however it should be noted that in the United State most prostatectomies that are done laparoscopicly are done with the help of a robot. This slide depicts how and what is removed at the time of radical prostatectomy. You can see a line outlining the prostate as well as the seminal vesicles which are rabbit ear-like organs that sit next to the prostate. These are removed along with the prostate at the time of surgery. Most radical prostatectomies are done with nerve sparing in mind. Nerve sparing can be done with either the the open or laparoscopic approach. The nerves run in bundles along both sides of the prostate. Sometimes nerves must be cut in order to remove the cancerous tissue. For example, if the cancer invades the nerves or grows too close to the nerves, the surgeon will not risk not getting all the cancer out, and takes the nerve with the cancer. If both sides of the nerves are cut or removed, the man will be unable to have an erection. This will not improve over time. There are interventions that may help restore erectile function, and we will discuss those in lecture five. If only one side of the bundles of nerves is cut or removed, the man may have less erectile function, but will possibly have some function left. If neither nerve bundle is disturbed during surgery, function may remain normal. However, it sometimes takes months after surgery to know whether a full recovery will occur. This is because the nerves are handled during surgery and may not function properly for a while after the procedure. What about radiation? Radiation kills dividing cells through DNA damage, which leads to cell death. As the cells sense DNA damage that they cannot repair, they actually choose to undergo programmed cell death, or apitosis. There are many types of radiation. Photons are the classic X-ray. Photon radiation releases energy before and after it hits a target. Proton beam therapy focuses beams of protons instead of X-rays. Protons cause little damage to tissues they pass through and release their energy only after traveling a certain distance. This means that proton beam radiation can, in theory, deliver more radiation to the prostate while doing less damage to nearby, normal tissues. In theory proton beam therapy might be more effective than using x-rays. So far, studies have not shown if this is true. And side effects have been similar. Currently, radiation delivered by electrons is under experimental development. Radiation delivered by neutrons has been tried for prostate cancer and abandoned as too toxic. External beam radiation therapy, or ERBT, is given in several doses or fractions over time. A total dose of 75-80 gray, which is a measure of radiation, is given over approximately 7 weeks. This radiation is given through conformal planning, the treatment is guided by CT scans. Shorter schedules with higher dose fractions are being tested, but the majority of men in the United States are still treated over 7 weeks of time with 75-80 gray. Intensity modulated radiation therapy, or IMRT, is an advanced mode of high-precision radiotherapy that uses computer-controlled linear accelerators to deliver precise radiation doses to the cancer or specific areas within the tumor itself. IMRT is now the most common type of external beam radiation therapy given for prostate cancer. The computer-driven machine moves around the patient as it delivers the radiation. Along with shaping the beams and aiming them at the prostate from several different angles, the intensity, or strength of the beams, can be adjusted to limit the doses reaching nearby normal tissue, as the machine moves around the patient. Some newer radiation machines have imaging scanners built right into them. This advance, known as image guided radiation therapy, or IGRT, let's the doctor take pictures of the prostate and make minor adjustments in aiming just before giving the radiation. Another variation of IMRT is called volumetric modulated arc therapy, or VMAT. It uses a machine that delivers radiation quickly as it rotates once around the body. This allows each treatment to be given over just a few minutes. Although this can be more convenient for the patient, It hasn't yet been shown to be more effective than regular IMRT. Brachytherapy, also called seed implantation or interstitial radiation therapy, uses small radioactive pellets, or seeds, each about the size of a grain of rice that are placed directly into the prostate. This is generally used only in men with early-stage, low-grade disease. Brachytherapy combined with EBRT is sometimes an option for men who have a higher risk of the cancer growing outside the prostate. There are two types of brachytherapy. Permanent, or low dose rate, or LDR bracytherapy is performed when approximately 100 pellets, or seeds, of radioactive material, such as iodine-125 or palladium-103, are placed into the prostate and left in place. Temporary brachytherapy, or high-dose rate, or HDR brachytherapy is done for a short time. Radioactive iridium-192 or cesium-137 are placed via implants for 5 to 15 minutes and then removed. Generally, about 3 treatments are given over 2 days.
