Radiation Therapy for Colorectal Cancer at Fox Chase Cancer Center

Penny R. Anderson, MD, chief of the division of Breast and Gynecologic Radiation Oncology, uses the most sophisticated technology for both external beam (IMRT) radiation therapy and brachytherapy to treat patients at Fox Chase Cancer Center.
Penny R. Anderson, MD, chief of the division of Breast and Gynecologic Radiation Oncology, uses the most sophisticated technology for both external beam (IMRT) radiation therapy and brachytherapy to treat patients at Fox Chase Cancer Center.

Treatment for your colorectal cancer can take many forms. If radiation therapy is a part of your treatment plan, you might be unsure of what to expect. Fox Chase has many options for radiation therapy, and your care team will put a comprehensive plan in place for your individual diagnosis, keeping you informed every step of the way.

Radiation Therapy: A Quick 101 Lesson

Radiation is the release of energy that kills cancer cells by damaging their DNA. Radiation therapy — also called radiotherapy — uses high doses of radiation to destroy cancer cells and shrink tumors.

If a cancer cell’s DNA is damaged beyond repair, it stops dividing and dies. At that point, those cells are broken down and removed by the body. This process can take multiple treatments, and cancer cells will continue to die for weeks or months after your radiation therapy ends.

Radiation can be used to:

  • Shrink cancer to allow for less invasive surgery
  • Shrink the cancer before surgery, to improve outcomes after surgery
  • Treat cancer that has spread beyond the colon or rectum
  • Treat cancer when surgery isn’t an option due to other health conditions, like age, obesity, or breathing problems due to smoking

Why You Can Benefit From Radiation Therapy

Radiation can help during different parts of your treatment for colorectal cancer. If the cancer is locally advanced — meaning it has spread to nearby tissue or lymph nodes — you might have radiation prior to surgery. It can keep the cancer from coming back, making the surgery more successful.

If your colorectal cancer is at an earlier stage, radiation can help shrink the cancer to allow for a less invasive surgery.

Sometimes surgery isn’t an option due to other health issues like smoking, age or obesity. If this is the case, and your physician thinks surgery is not ideal for you, radiation may be another option for treating your cancer.

Finally, if your cancer has spread from the colon or rectum to another part of the body — called metastatic cancer — you may benefit from radiation to treat the primary cancer (colorectal cancer) as well as the secondary cancer (cancer that has spread) using a more aggressive radiation therapy regimen.

Your Advanced Radiation Therapy Options at Fox Chase

At Fox Chase, our radiation team has the expertise to know how to cater treatments to your individual needs, in order to fight your colorectal cancer most effectively. All of our advanced forms of radiation therapy allow for precision, strength, and safety for the patient.

Two forms of radiation therapy, Intensity Modulated Radiation Therapy (IMRT) and Three-Dimensional Conformal Radiation Therapy (3DCRT), allow your physician to maximize the radiation’s ability to destroy cancer cells by delivering doses that are more targeted — meaning that they are delivered just to the tumor and at-risk areas. This makes them safer, causing fewer and less intense side effects. These two methods also reduce the damage to healthy, surrounding tissue and organs. They also limit the amount of side effects that you may experience.

Intensity Modulated Radiation Therapy (IMRT)

Intensity Modulated Radiation Therapy (IMRT) uses a device called a linear accelerator to deliver precise radiation doses to a tumor in a safe and painless way. It also minimizes the dose to any surrounding tissue.

During IMRT, high energy X-rays or electrons — which are shaped as they exit the machine — are delivered to the exact location of the tumor in order to provide high levels of radiation to a specific area, while sparing the areas around it.

Three-Dimensional Conformal Radiation Therapy (3DCRT)

Three-Dimensional Conformal Radiation Therapy (3DCRT) uses a computer to create a 3-D image of the tumor, which allows your physician to deliver higher doses of radiation directly to the tumor, while impacting as little surrounding tissue as possible.

IMRT and 3DCRT: What’s the Difference?

3DCRT means that the machine’s output is planned for your specific needs. This means that the radiation oncologist chooses the parameters — like number, direction, shape, and weight of radiation beams — and the computer calculates the dose you will receive.

IMRT works the opposite way: The radiation oncologist determines the dose of radiation based on your individual needs first. Then, the computer calculates the beam parameters that it will deliver. This involves splitting the radiation beams up into hundreds of tiny segments that together make up an optimal plan.

What to Expect During Radiation Therapy

Prior to any radiation treatments, your physician will conduct a treatment simulation using a computed tomography (CT) scan. This will determine the exact shape and location of the tumor. You may also have a hardened foam mold specifically designed for you during that simulation, which you will use to remain in the same position for your treatment sessions.

Multiple treatment sessions will be required. The number of sessions depends on your individual situation based on the type, location, and size of the tumor, as well as your overall health.

During the treatment sessions, your radiation therapist will position you on the treatment table to ensure the treatment area is in the proper place under the machine that will deliver the radiation.

You may need to be re-positioned during the treatment, and sometimes your therapist will use imaging — like an X-ray or CT scan — to ensure the radiation is directed at the right location. The treatment session itself will take 10 to 30 minutes and should not be painful.

Side Effects of Radiation Therapy

Early side effects can occur immediately after the treatment and typically go away within a few weeks. These include:

  • Fatigue
  • Skin problems, like redness, sensitivity, and swelling
  • Other skin irritations, like itching, dryness, peeling, and blistering
  • Decreased appetite
  • Dehydration
  • Weight loss
  • Changes in urination and bowel habits

Many early side effects can be managed with medications, so be sure to let your physician know if you are experiencing any of them.

You can also minimize side effects by coming to treatment will a full bladder. Your bladder can change size depending on how full it is. When it’s full, the medical team can ensure the radiation is directed only at the colon or rectum.

Because radiation therapy can also destroy infection-fighting white blood cells, your immune system may be weakened during treatment. Therefore, take care of yourself by getting plenty of rest, eating a healthy amount of fruits and vegetables, and avoiding unnecessary exposure to infectious germs.

Late side effects can occur months or years following treatment and are usually permanent. These include:

  • Colon and rectal issues, like diarrhea and rectal bleeding
  • Joint issues, like stiffness and soreness
  • Infertility
  • Decreased potency in male patients
  • Small bowel obstruction
  • Pelvic fracture in patients with osteoporosis/osteopenia

The good news is these side effects are rare. If you suspect you have any of these late side effects, you should inform your physician right away. There are ways your care team may be able to treat them and help improve your symptoms.

Monitoring the Success of Your Radiation Treatment

If you have radiation therapy prior to surgery, the success of the radiation therapy can be determined based on the surgery’s success. This is because the goal of radiation therapy before surgery is to shrink the tumor. So surgery will give us information about how successful the radiation was.

We will continue to work closely with you after treatment. You will come in for follow-up appointments about every 3 months. During these appointments, your physician will use CT scans and blood tests to confirm that the cancer has not returned.