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Long-Term Side Effects of Prostate Cancer Radiotherapy

By Abdullah Sarwar
Last Update August 1, 2023

As a medical professional, I understand the significance of radiotherapy in treating prostate cancer. While radiotherapy effectively targets cancer cells, it is essential to recognize that some side effects may arise during the course of treatment and persist in the long term. This article aims to shed light on these potential side effects and the measures we take to manage and address them.

Overview of Radiotherapy Side Effects

Radiotherapy employs radiation to eliminate cancer cells while minimizing harm to healthy tissue. Despite our efforts to optimize treatment precision, side effects can occur, and their severity may vary depending on factors such as dosage, treated area, and the patient’s health condition. While most side effects resolve within a few weeks after treatment completion, some may persist in the long term. Oncology teams work closely with patients to manage these side effects and enhance their quality of life during and after radiotherapy.

Urinary and Bowel Side Effects

The urinary and bowel systems may be affected by radiation exposure, leading to various challenges. Bladder and bowel dysfunction is quite common during and soon after radiotherapy. In most cases, they settle down with time but some patients suffer from long-term problems with bowel and bladder function. The risk of side effects is higher if the patient has pre-existing bowel and bladder problems.

Problems Passing Urine and Leakage

Up to 20% of patients may experience long-term urinary issues, such as increased frequency, urgency, painful urination, and rarely incontinence.

Difficulty with Erections (Impotence)

Erectile dysfunction, impacting approximately 50% of prostate cancer patients after radiation, is a common concern. Oral medications like Viagra may help restore erectile function, and for more complex cases other treatments including penile implants can be considered.

Bowel and Back Passage Problems:

Radiation-induced irritation to the colon or rectum can lead to diarrhea, rectal bleeding, pain, and incontinence. These may include a change in bowel frequency (constipation or diarrhea), bleeding on moving bowels (less than 10% risk with modern radiotherapy techniques), incontinence( which is rare), and pain. These can be treated through dietary adjustments and the use of medications.

Other Potential Long-Term Side Effects

While less common, some side effects may persist in the long term:

Swollen Legs or Scrotum:

Radiation-induced damage to the lymph system may cause fluid buildup. Elevating the legs and incorporating exercises can assist in reducing swelling.

Second Cancers:

Although there is a very small risk of developing another cancer later, the overall likelihood remains low (less than 5% in the next 10-30 years).

Bone Problems:

In some cases, pelvic radiation may weaken bones over time. To counter this effect, doctors can prescribe medications to strengthen bones and minimize the risk of fractures. Additionally, weight-bearing exercises are recommended.

Low Vitamin B12 Levels:

Radiation may impact the absorption of vitamin B12. To prevent deficiencies, oncology teams closely monitor patients’ bloodwork and may recommend appropriate supplements.

Coping with Side Effects

Ensuring patients’ well-being and comfort is paramount. A comprehensive approach includes connecting patients with valuable resources, such as:

Support for Patients and Their Families

Emotional struggles are not uncommon, and we encourage patients to seek counseling support. Engaging in support groups allows patients to connect with others facing similar challenges. 

Physical therapy is also a beneficial option.

Expectations After Radiation Treatment

Following the completion of radiotherapy for prostate cancer, side effects may initially worsen before gradually improving. Acute side effects typically resolve within a few months.


Oncology teams are dedicated to patient-centric care and understand that a cancer diagnosis can be overwhelming. Throughout the treatment journey, whether patients choose to pursue radiotherapy or consider other options, doctors prioritize their well-being and dignity. An individualized approach tailors radiation therapy to each patient’s unique needs, providing unwavering support and understanding throughout the entire process.

Hi, We are Killing Cancer Kindly

Dr. Khan is a Clinical Oncologist currently working in the NHS UK with more than 20 years of clinical experience.
Killing Cancer Kindly is the result of years of painstakingly analyzing the available web content and combining it with Dr Khan’s extensive oncological experience to create a comprehensive and pragmatic list of ‘Dos’ and ‘Don’ts’ for anyone affected by cancer.