External Radiotherapy for Prostate Cancer: What to Expect

External beam radiation therapy (EBRT) is a form of radiotherapy delivered by machines surrounding your body. The machines do not touch you and you will not feel claustrophobic. It’s the most common radiotherapy treatment for cancer. High-energy radiation beams, which are invisible, target your tumor and damage the DNA inside the cancer cells, such that they die.

• How many radiotherapy sessions for prostate cancer? / How long is radiotherapy for prostate cancer?

If you are undergoing intensity modulated radiation therapy (IMRT), up to 40 to 45 once-daily sessions (excluding weekends and national holidays) may be needed over two months.

For stereotactic body radiation therapy (SBRT), around 5 sessions may be needed over up to two weeks.

• Does radiotherapy cure prostate cancer?

Radiotherapy is a comparable option to surgical removal of the prostate when considering treating prostate cancer at an intermediate risk of progression. When facing high-risk prostate cancer, your doctor may suggest combining it with androgen deprivation therapy.

Before starting radiotherapy, your doctor will arrange for a treatment planning session. Here, your prostate will be imaged (e.g. by CT scan) in order to map out the exact position of the tumor, and select the best targets for treatment. Your body may be marked with permanent small black tattoo dots to act as a guide during your treatment sessions.

You may need to take laxatives before the treatment to ensure that your rectum is empty before the procedure. Additionally, about half an hour before the imaging, you would need to drink enough to fill your bladder, in order to lift the small bowel away from the prostate region and minimize exposure to radiation.

• What does radiotherapy feel like?

Similar to undergoing an X-ray, you will not be able to feel anything from the radiation. The side effects of treatment may take two or three weeks to appear.

There are a few side effects of radiation for prostate cancer, and most patients will experience at least some of the following soon after the treatment:

• Increase in the frequency and urgency of urination
• Weak urination stream
• Difficulty starting urination
• Burning or tingling with urination
• Occasional diarrhea
• Increased frequency of softer and smaller bowel movements
• Hemorrhoids or rectal irritation (blood may be seen)
• Fatigue

While most of these side effects will subside over time, other long-term side effects may accompany radiotherapy treatment, including a general decline in sexual function and fertility. However, if you see blood in your urine, or are completely unable to urinate, you should contact your doctor. Additionally, if the side-effects are unmanageable, your doctor may be able to prescribe medications to reduce diarrhea or urination frequency, or ease the discomfort caused.