Radiotherapy has long occupied an important role in the treatment of prostate cancer. In fact, it was over 100 years ago that the first prostate cancer patient received radiotherapy.
Today, radiotherapy and surgery are the cornerstones for treatment in prostate cancer
patients. Significant advancements in both have been realized over the past 25 years providing the early stage patient with two highly effective treatment approaches with comparable outcomes.
- Radiation therapy may be delivered alone in patients with low risk disease
- Radiation therapy following surgery, either immediately in patients with high risk factors or in those with a rising PSA
Radiotherapy is also used for patients with more advanced disease, typically in conjunction with hormone deprivation, and in patients with symptomatic bone metastases.
External Radiation
- Until recently, external beam radiotherapy using 3D conformal radiation therapy (3DCRT) was the conventional approach. In this technique, multiple beams are used to focus the radiation dose on the target tissues reducing the volume of the bladder and rectum receiving high doses.
- Intensity modulated radiotherapy (IMRT) is the most commonly used radiotherapy for prostate cancer today. Unlike conventional approaches, IMRT conforms the radiation dose to the shape of the target tissues in 3-dimensions, reducing the dose delivered to the nearby normal tissues including the rectum and bladder. IMRT has been associated with excellent outcomes with less toxicity.
Ask your Radiation Oncologist whether IMRT is right for you. IMRT is the standard approach in all prostate cancer patients treated at UCSD.
Internal Radiation (Brachytherapy)
Brachytherapy, or internal radiation therapy, involves dozens of tiny radioactive seeds being implanted in the diseased tissue. The seeds release radiation for weeks or months, after which they are no longer radioactive. The radiation in the seeds can't be aimed as accurately as external beams, but are less likely to damage normal tissue. Once the seeds have lost their radioactivity, they become harmless and can stay in place indefinitely.
High-Dose-Rate (HDR) Brachytherapy is also emerging as a treatment option. HDR brachytherapy is typically combined with external bean radiotherapy to treat high risk disease. This technique enables a highly conformal and biologically effective radiation dose to be delivered to prostate.
These innovative techniques will soon be available at UCSD.
Image guided Radiation therapy (IGRT)
Image-Guided Radiation Therapy (IGRT) refers to the use of modern imaging to improve the targeting and delivery of radiation treatment. With IGRT, a patient can be imaged in the treatment room while on the treatment table. This is a major advancement in that previous techniques required that patients be imaged once at the beginning of treatment and only periodically during treatment. Now, patients are imaged everyday immediately prior to treatment.
At UCSD, IGRT is delivered on a Varian Trilogy, a sophisticated, state-of-the-art linear accelerator equipped with an on-board imager (OBI).
In prostate cancer patients, small seeds are routinely implanted prior to treatment and used to locate the precise position of the prostate prior to each treatment. The treatment couch is then adjusted to return the prostate to the same position as at simulation. Such adjustments are needed because the position of the prostate may change from day to day, due to differences in the amount of air in the rectum and urine in the bladder. Daily prostate localization is essential to ensuring that treatment is delivered consistently and accurately. IGRT provides an opportunity to improve therapeutic ratio by safely escalating the dose to the target and at the same time minimizing the dose to normal tissues by reducing the excessive margins required with the conventional approaches.
At UCSD, we routinely use IGRT for patients requiring radiotherapy following prostatectomy. In this situation, surgical clips or CBCT is utilized to localize the prostate bed daily prior to treatment.
An additional feature of the Varian Trilogy is the ability to generate volumetric images of the patient, known as cone-beam CT (CBCT) imaging. CBCT images are obtained by rotating the OBI imager around the patient and reconstructing the 2D images into 3D ones.
High-quality CBCT images are produced by the Varian Trilogy quickly and with only a modest dose to the patient. In contrast, other IGRT approaches (such as Tomotherapy) use megavoltage X-rays. The result is inferior quality images and higher doses to the patient.
The ability to generate high-quality kV CBCT images of the patient on the treatment table immediately prior to treatment is nothing short of revolutionary. Such images can be used to more accurately setup patients based on internal anatomy without the need for implanted fiducial markers.
Urologic Radiation Team
Ajay Sandhu M.D. is the Chief of the Prostate Cancer (Genitourinary) Service in the UCSD Department of Radiation Oncology. Dr. Sandhu has considerable experience in the treatment of prostate cancer and other genitourinary malignancies with latest radiotherapy techniques including intensity modulated radiation therapy (IMRT) and image-guided radiation therapy (IGRT).
Working with Dr. Sandhu is Radiation Nurse, Polly Nobiensky, R.N.
All patients consulted at UCSD are presented and discussed at a multi-disciplinary Prostate Cancer (Genitourinary) Conference, at which our entire team of Urologic Cancer specialists collaborates to ensure the best possible treatment options are made available to each patient.