MSK experts use CT scans and other imaging methods to guide them in selecting the best radiation therapy for prostate cancer. Our radiation oncologists use advanced tools to target the cancer with precision while minimizing side effects.
The latest treatments for prostate cancer have become more effective, convenient, and personalized for patients than ever before. Among the most powerful tools is radiation therapy, which can be delivered in multiple ways to target prostate cancer with precision, while minimizing side effects.
To help patients and their families understand their choices, Memorial Sloan Kettering Cancer Center (MSK) experts explain the latest approaches to prostate cancer radiation therapy, including how treatments are tailored to each patient’s needs.
What are the main types of radiation therapy for prostate cancer?
Radiation therapy is broadly divided into two categories, external beam radiation therapy (EBRT) and brachytherapy.
1. External Beam Radiation Therapy (EBRT)
External beam radiation therapy delivers radiation from outside the body, most often in the form of X-rays. At MSK, two main approaches are used to deliver EBRT:
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Stereotactic body radiation therapy (SBRT) : This highly focused, image-guided treatment can be completed in just five sessions over one to two weeks. (This is called ultra-hypofractionated radiation therapy.) It delivers high doses of radiation to the tumor with precision right down to the millimeter, minimizing impact on surrounding tissues.
- Hypofractionated Intensity-Modulated radiation therapy (IMRT): IMRT uses advanced computer programs to calculate and deliver radiation directly to cancer cells from different angles. It allows the radiation dose to conform more precisely to the shape of the tumor by changing the radiation beam into multiple smaller beams. IMRT for prostate cancer is typically delivered over four to five weeks.
2. Brachytherapy
Brachytherapy uses radioactive material sealed inside a seed, pellet, wire, or capsule that is implanted in the body using a needle or catheter. The two main forms are low-dose rate (LDR) and high-dose rate (HDR).
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Low-Dose-Rate (LDR): Radioactive seeds are permanently implanted in the prostate while the patient is under anesthesia, delivering radiation over several months.
- High-Dose-Rate (HDR): Catheters deliver high-intensity radiation in one or two brief sessions and then are removed. HDR can be combined with EBRT for intermediate or high-risk prostate cancers.
What Is Brachytherapy?
How does SBRT work, and what makes it an appealing treatment choice?
SBRT uses sophisticated image guidance to deliver extremely precise doses of radiation to cancer cells while minimizing damage to healthy tissue. MSK is using SBRT for more patients because it’s a major leap forward in radiation treatment:
- Fewer sessions: SBRT can be given in just five short visits compared with 20-45 visits needed with conventional radiation.
- Excellent outcomes: Multiple randomized clinical trials have shown that SBRT is very effective at controlling cancer.
- Few side effects: SBRT has low rates of urinary and bowel problems.
- Highly personalized: SBRT is guided by advanced imaging techniques according to each person’s cancer, including magnetic resonance imaging (MRI) and PSMA PET imaging, an FDA-approved scan that can pinpoint prostate cancer cells throughout the body.
What Is Hypofractionation?
Is one type of radiation better than another for prostate cancer?
There is no one-size-fits-all approach to treat prostate cancer. Every patient’s disease is different and so are their concerns about their quality of life. MSK experts choose the best form of radiation therapy based on several factors, including:
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Cancer risk level: The stage and grade of the cancer can help determine which radiation therapy is best. For low- or favorable intermediate-risk disease, some patients may receive close monitoring (“active surveillance”) before receiving any treatment. For others in this group, SBRT or brachytherapy, or surgery alone may be effective.
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Patient’s health and physical factors: Larger prostate glands can make it more challenging to deliver SBRT effectively and may increase the risk of urinary side effects. For patients with a large prostate or existing urinary problems, conventional radiation using IMRT — or surgery – may instead be preferred.
- Patient preferences and lifestyle: Some patients prefer the convenience of brachytherapy or SBRT because they require fewer sessions.
Are different types of radiation therapy ever combined to treat a patient?
For patients with high-risk prostate cancer, combining radiation types (for example high dose-rate brachytherapy + external beam radiation) may offer better outcomes:
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For brachytherapy, we use real-time ultrasound scans combined with MRI data gathered before the procedure to plan and guide treatment, as well as to intensify the dose of radiation in regions of the prostate that require a more aggressive approach.
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Sophisticated computer-based planning techniques help reduce the dose of external radiation given to normal tissues.
- We routinely use a rectal spacer gel, which we inject between the prostate and the rectum to create a buffer between those two tissues. The further reduces the dose of radiation to which the rectum is exposed.
What is MRI-guided radiation therapy?
At MSK, patients have access to real-time MRI-guided radiation therapy, a technology that allows doctors to see the prostate and surrounding organs as they deliver radiation. While not necessary for all patients, this approach is especially helpful for people with more complex anatomy or tumors located close to sensitive structures.
MRI-guided radiation therapy allows doctors to:
- Adjust for movement of the prostate, bladder, or rectum that may occur from one treatment to the next — or even during a single session.
- Adapt the treatment plan on the spot, if necessary, to maintain precision and protect nearby healthy tissue.
- Potentially further reduce side effects, such as urinary problems or rectal irritation, by minimizing radiation exposure to surrounding organs.
What is CT-based adaptive radiation therapy for prostate cancer?
Another advanced technique used at MSK is CT-based adaptive radiation therapy, which allows doctors to adjust the treatment plan based on daily changes in your anatomy. It uses high-quality imaging and sophisticated software.
How is CT-based adaptive radiation therapy done?
Before each treatment, a specialized CT scan is taken while the patient is on the treatment table. This scan shows if the bladder, rectum, or prostate have shifted from their original position due to natural day-to-day changes. If the anatomy is different from the original plan, the care team can adapt the radiation fields in real time — ensuring the tumor remains accurately targeted and surrounding healthy tissue is spared.
What’s recovery like after prostate cancer radiation therapy?
Most patients continue normal activities during and after radiation. Common short-term side effects may include:
- A need to urinate more urgently or more often
- Temporary changes in bowel function
These symptoms typically go away within weeks to a few months. The long-term outcomes are good:
- Extremely low rates of incontinence (uncontrollable loss of urine from the bladder)
- Preservation of sexual function in many patients
- Excellent quality of life
How does MSK create a treatment for each patient?
Our initial assessment includes a carefully evaluated biopsy and a very detailed MRI to show the location of the tumor, the integrity or soundness of the capsule surrounding the prostate, and the amount of disease. We will often obtain next-generation imaging (for example, PSMA PET) and also perform genomic and multimodal artificial intelligence testing (which processes information from different data sources). Then, based on that information — and with input from the urologist, the radiation oncologist, and the medical oncologist — we can provide a comprehensive recommendation.
Our doctors have expertise in multiple areas of prostate cancer radiotherapy management. Some places just focus on external radiation alone. Some just do seed implants. Other centers do combined therapies for everybody. It’s our expertise in all these areas that gives us an opportunity to provide an approach that’s tailored to each person, not one-size-fits all.
Our goal is to try to reduce the burden or side effects of radiation therapy on our patients. If we can use our technology and expertise to combine therapies or condense prostate cancer treatment from two and a half months down to sometimes as little as a week, we can eradicate our patients’ disease and preserve their quality of life.
