Radiation Therapy for Colorectal Cancer

Radiation therapy for colorectal cancer is a common treatment that kills cancer cells and shrinks tumors. It often follows or precedes surgery to increase the chances of removing or destroying all the cancer.

While not always the first option for colon cancer, it plays a key role in treating rectal cancer. Depending on the stage and location of the tumor, radiation therapy may be used alone or combined with chemotherapy or surgery.

When Is Radiation Therapy Used for Colorectal Cancer?

Radiation therapy for colorectal cancer uses powerful energy to kill cancer cells and shrink tumors. Doctors often use it before or after surgery to improve the chances of removing or destroying all the cancer.

Although radiation is not usually the first choice for colon cancer, it plays an important role in treating rectal cancer. Depending on the tumor’s stage and location, doctors may use radiation alone or combine it with chemotherapy or surgery.

Why Choose Radiation Therapy for Colorectal Cancer?

Choosing radiation therapy for colorectal cancer depends on your stage, tumor location, and overall treatment plan. Here are three key reasons why it may be the right option:

Targets Cancer Precisely

With techniques like external beam radiation therapy (EBRT) and intensity modulated radiation therapy (IMRT), radiation can destroy cancer cells while protecting nearby healthy tissues.

Reduces Tumor Size Before Surgery

Radiation is often used before surgery to shrink tumors, making them easier to remove and improving long-term outcomes.

Helps Prevent Recurrence

After surgery, radiation therapy helps eliminate remaining cancer cells, reducing the chance of the cancer coming back.

Types of Radiation Therapy for Colorectal Cancer

There are different types of radiation therapy for colorectal cancer. Each one has its own approach, benefits, and side effects. The most common form is external beam radiation therapy (EBRT).

External Beam Radiation Therapy (EBRT)

EBRT is the most common type of radiation used in the treatment of colorectal cancer. In this method, high-energy X-rays are sent from a machine outside the body to the cancerous area. The goal is to destroy cancer cells without harming too many nearby healthy tissues.

Intensity-modulated radiation therapy (IMRT) is an advanced type of external beam radiation therapy (EBRT). This method shapes the radiation beams to match the tumor’s exact shape. It delivers high doses directly to the tumor and limits exposure to nearby healthy tissues. IMRT lowers the side effects of radiation therapy for colorectal cancer, especially when tumors sit close to organs like the bladder or small intestine.

Brachytherapy (Internal Radiation)

Though less common, some cases may use internal radiation, or brachytherapy. This method places radiation directly inside the rectum or near the tumor. It’s sometimes used in clinical trials or in specific medical centers.

What to Expect During Radiation Treatments

Radiation therapy is usually done five days a week for several weeks. Each session takes only a few minutes, but the full course can last 5–6 weeks.

During the first visit, your team will perform treatment planning using CT scans or MRIs. This helps map out where to aim the radiation beams.

Measuring Radiation Doses for Safe Treatment

The doses of radiation are carefully measured to ensure they’re high enough to kill cancer cells, but not so strong that they damage healthy organs.

Most people can return to daily activities soon after each session, though rest is still important during treatment.

Managing Side Effects of Radiation Therapy

Radiation does not hurt during treatment. Over time, you may feel tired and notice changes in your bowel movements, skin irritation in the treated area, or other short-term effects.

You can often manage these effects with medication, hydration, and small lifestyle changes.

Common Side Effects of Radiation Therapy

While radiation therapy for colorectal cancer is effective, it can come with side effects. These usually appear after a few weeks and may include:

Fatigue: A common side effect due to the body repairing itself.
Changes in bowel movements: Some people experience
diarrhea or constipation.
Skin reactions: The treated area may become red, sore, or dry.
Urinary discomfort: Radiation near the bladder may cause frequent urination.

Doctors work to prevent or manage these issues through supportive care. IMRT and careful planning help limit side effects by avoiding unnecessary damage to nearby healthy tissues.

Most side effects go away within a few weeks after treatment ends. If you experience anything unusual, it’s important to report it to your care team.

Final Thoughts on Radiation Therapy for Colorectal Cancer

Radiation therapy plays an important role in the treatment of colorectal cancer, especially for rectal tumors. With advanced techniques like EBRT and IMRT, it’s possible to treat colorectal cancers more precisely while minimizing harm to healthy tissues.

At Onco Life Centre, we focus on your full care journey. Our expert team works closely with trusted radiation oncologists to ensure your treatment plan is seamless and coordinated. We help manage each part of your care to provide you with the most effective options and strong support throughout your treatment process.

Understanding your treatment options is key to making the best decision for your health. Whether you need surgery, chemotherapy, or radiation treatments, your care team will create a plan that works for you.

Your Journey

Start Your Recovery

Our dedicated Patient Navigator will assist you with appointment scheduling. Contact us at +6012-3993260 (Call or Whatsapp ).

First Consultation

On appointment day, bring along all the medical reports and your identity documents, ie. identity card or passport. Our team will help you organize the medical reports for our oncologist to review. Our oncologist will discuss the treatment plan with you. Tele-consult is available for overseas patients.

Treatment Day

Come to our center on an agreed date and time for the treatment. Our team will take good care of you. You will be discharged on the same day. Yes, you will get to go home after every treatment visit as no overnight admission is required.

Stay on Track

Our dedicated patient navigator will be following up with you post treatment to check on your condition, to ensure that you are doing well. You will receive a reminder message on your phone for the next appointment date.

Dr. Christina Ng Van Tze

Consultant Medical Oncologist
Medical Director
MBBS (Melb) FRACP (Aus)

Monday - Friday : 08:00 AM TO 06:00 PM

Saturday : 08:00 AM TO 02:00 PM

D. Joseph K. Joseph

Consultant Medical Oncologist
MBBCH, BAO (IRE) MRCP (UK)

Wednesday : 08:00 AM TO 12:00 PM

Friday : 08:00 AM TO 12:00 PM

Advocacy Programs

Onco Life Centre Wins 2025 Best Oncology Clinic in Malaysia

We are proud to share that Onco Life Centre has been named the Oncology Clinic and Treatment Centre of the Year in Malaysia at the GlobalHealth Asia-Pacific Awards 2025, held in Bangkok.

This prestigious recognition is a testament to our unwavering commitment to delivering personalized, compassionate, and cutting-edge cancer care to our patients. The award reflects not just our clinical excellence, but our dedication to safety, community outreach, and innovation in oncology services.

The GlobalHealth Asia-Pacific Awards celebrate leading healthcare institutions across the region. Winners are chosen based on a comprehensive evaluation of criteria such as:

Excellence and Innovation: Transforming healthcare delivery and patient outcomes through progressive medical practices.
Patient Safety: Upholding the highest standards to ensure safe, comfortable, and effective treatment environments.
Community Involvement: Actively engaging in public awareness, screening programs, and care for underprivileged communities.
Technology Adoption: Integrating advanced diagnostics, therapies, and digital tools to enhance every aspect of care.
Impact and Measurable Results: Demonstrating tangible improvements in cancer detection, treatment success, and patient well-being.
Adaptability and Preparedness: Being resilient and forward-thinking in the face of global health challenges.
Leadership and Vision: Cultivating a culture that prioritizes empathy, innovation, and ongoing education.

This award inspires us to continue raising the bar in oncology care—not only through medical advancements but by remaining deeply rooted in our advocacy mission: to serve, educate, and empower every cancer patient, especially those most in need.

We dedicate this achievement to our patients, survivors, caregivers, and the entire Onco Life Centre community. Your courage fuels our purpose. Together, we will continue the fight—because every life matters.