RADIATION THERAPY

Radiation therapy uses high-energy beams, such as X-rays or gamma rays, to kill cancer cells and shrink tumors.

These beams damage DNA inside cells, which can result in the death of cancer cells and/or the slowing of cancer growth. While radiation is also toxic to healthy cells, cancer cells are especially vulnerable to DNA damage because of their quick division. Radiation is given in regular doses over time and it is less invasive than surgery.

External Beam Radiation Therapy (EBRT)

External Beam Radiation Therapy is the most common form of radiation used to treat prostate cancer. It is often used with the goal of curing early-stage cancers. Radiation is delivered from outside the body using a machine that directs precise, high-energy beams at the prostate. The radiation passes through the skin and surrounding tissue to reach the tumor, targeting cancer cells while minimizing exposure to healthy tissue. Modern techniques allow higher doses to be given safely, effectively, and sometimes in fewer treatments. EBRT combined with hormone therapy is the recommended initial treatment for patients with high-risk localized prostate cancer.

Intensity-Modulated Radiation Therapy (IMRT)

IMRT is the most widely used and advanced form of external beam radiation therapy for prostate cancer. It builds upon an earlier technique called 3D Conformal Radiation Therapy (3D CRT), which uses MRI, CT, and/or PET imaging to create a three-dimensional model of the prostate and shape the radiation beams to match the tumor’s outline. IMRT improves upon this by using computer-controlled beams that can vary in both shape and intensity, conforming even more precisely to the prostate while avoiding nearby healthy organs such as the bladder and rectum.

This precision allows doctors to deliver higher doses of radiation to the prostate with fewer side effects. IMRT has largely replaced 3D CRT as the standard of care and is supported by long-term data showing excellent cancer control and reduced urinary and bowel complications compared to older methods.

Volumetric Modulated Arc Therapy (VMAT)

VMAT is a variation of IMRT that delivers radiation continuously as the machine rotates around the body. This approach shortens treatment time while maintaining similar accuracy. Early results show comparable effectiveness to IMRT, though long-term studies are ongoing.

Image-Guided Radiation Therapy (IGRT)

Because the prostate can shift slightly within the body between treatments, IGRT uses imaging taken just before or during each radiation session to verify the prostate’s exact position. This ensures that radiation is delivered accurately to the target area, improving the precision of both IMRT and VMAT treatments.

Proton Beam Therapy

Proton Beam Therapy uses beams of protons instead of X-rays. Protons release most of their energy directly in the tumor, causing less damage to nearby tissues. This allows for more targeted treatment and may reduce side effects. Proton therapy can be planned using the same 3D and IMRT techniques described above. While promising, current studies have not yet shown clear evidence that proton therapy is more effective than advanced X-ray-based approaches like IMRT.

Stereotactic Body Radiotherapy (SBRT)

SBRT delivers very high doses of radiation in a small number of treatments—often five sessions or fewer. Before treatment, small markers are placed around the prostate to guide precise targeting. SBRT may be an option for select patients with localized prostate cancer seeking a shorter course of therapy. Some studies suggest side effects can be slightly higher than with IMRT, though results vary, and ongoing research is clarifying its role.

Brachytherapy (Internal Radiation Therapy)

Brachytherapy involves placing tiny radioactive implants, often called “seeds,” directly into the prostate. The procedure is guided by ultrasound and imaging to ensure accurate placement. Like EBRT, 3D imaging is used to map the prostate and calculate the dose and placement of the seeds. Brachytherapy can be used alone for low-risk cancers or combined with external beam radiation for intermediate- or high-risk disease.

There are two main types of brachytherapy:

• Low-Dose Rate (LDR) Brachytherapy: Seeds emit low doses of radiation over several weeks or months. The seeds remain permanently in the prostate but become inactive over time. This method minimizes damage to nearby tissues and is commonly used for early-stage cancer.
• High-Dose Rate (HDR) Brachytherapy: Temporary radioactive sources deliver higher doses over a short period. The radiation source is removed after each session, typically over several treatments within a few days. HDR may be used alone or combined with EBRT for more aggressive cancers.

Brachytherapy is less invasive than surgery and can provide excellent long-term cancer control in carefully selected patients. However, it may not be suitable for men with very large prostates or significant urinary symptoms before treatment.

Radiopharmaceutical Therapies

Radiopharmaceutical therapy uses injectable radioactive medicines that travel through the bloodstream to target prostate cancer cells throughout the body. These treatments can deliver radiation directly to cancer sites while sparing most healthy tissue.

Lutetium-177 (PSMA-Targeted Therapy)

Lutetium-177 (Pluvicto) is a targeted therapy that attaches to the PSMA protein found on prostate cancer cells. Once bound, it delivers radiation directly to those cells, destroying them from within. It is given as an intravenous infusion once every six weeks, for up to six doses. Lutetium-177 is FDA-approved for men with advanced or metastatic prostate cancer that expresses PSMA.

Radium-223 (Xofigo)

Radium-223 is used when prostate cancer has spread to the bones but not to other organs. It mimics calcium, allowing it to localize in bone tissue where it releases short-range radiation that kills cancer cells and helps reduce bone pain. It is given as a monthly injection for six months and is FDA-approved for men with symptomatic bone-dominant metastatic prostate cancer.

Together, these radiation-based treatments offer multiple options depending on the stage, location, and aggressiveness of the cancer. Your care team will help you determine which approach (or combination of approaches) is best suited to your specific diagnosis and overall health.