Advanced Radiation Therapy for Colorectal and Anal Cancer

Colorectal and Anal Cancer Treatment Side Effects

Managing side effects of radiation treatment for colorectal and anal cancer

Why is it important to have an empty rectum and full bladder?

Your bladder and rectum are very close to other organs in your pelvis and their size can affect their position.  By keeping these organs the same size for your simulation and daily radiation treatments, your radiation therapy will be more accurate.  This will also help to reduce some of the side effects of your radiation therapy.

Please follow the below instructions on the day of your simulation and each day of your radiation treatments:               

You can maintain a full bladder for simulation and treatment by:

  • 75 minutes before your simulation/treatment you should first urinate and then drink 20 ounces (2 ½ cups) of water. We recommend that you complete drinking the 20 ounces of water 1 hour before your simulation/treatment to avoid delays.  
  • Don’t urinate again until after your simulation/treatment.
  • If you are unable to hold the urine for that full hour, please let your nurse or therapist know.

You can maintain an empty rectum for simulation and treatment by:

  • Trying to have a bowel movement within the 4 hours prior to your simulation and each of your radiation treatments. Try to pass any gas 1 hour prior to simulation and each treatment.  If you do not have a bowel movement every day please talk with your nurse.

Up to 30% of colorectal cancer patients have a family history of the disease, about 5% of which are due to an inherited genetic abnormality. People with a parent, sibling, or child who has been diagnosed with CRC have 2 to 4 times the risk of developing the disease compared to people without this family history. - American Cancer Society

You will be receiving radiation therapy treatments to the pelvic area of your body.  Some of the possible side effects that you may experience during treatments can include: fatigue, skin irritation, diarrhea, and nausea.  Measures that you can take to minimize these side effects are listed below.

  • Skin Care:

    It is okay to bathe or shower daily with a mild soap. Wash the treatment area gently.  Do not scrub the skin. If you have ink marks on your skin, please do not wash them off.  Gently pat the skin dry.

    During the course of your radiation therapy treatments, we ask that you put nothing on the skin in the treatment area except for the products recommended by the physician or nurse.    Use moisturizers for dryness and over-the-counter hydrocortisone cream for itchiness. Apply products twice daily or as needed.  We do not want the skin “greasy” when you come in for treatment.

    Avoid the use of hot or cold in the treatment area.  This includes the use of heating pads, hot packs, hot water bottles, ice packs, and ice bags.  It is okay to use an electric blanket.  Avoid the use of tape or Band-Aids in the treatment area.

  • Sun Exposure:

    During treatment, avoid exposing the skin in the treatment area to direct sunlight or tanning beds. If you plan on being in the sun for an extended period, cover the skin with clothing or broad-spectrum sunscreen with an SPF of 30 or higher. The treatment area will always be more sensitive to the sun and tanning beds.

  • Nausea/Vomiting

    You may feel slightly nauseous during your course of therapy.  Some medications help control the nausea.  You may need to take nausea medication before each treatment and continue to take it on a regularly scheduled basis throughout your treatments.  The nurse will discuss anti-nausea medications with you.

  • Fatigue:

    Loss of energy is a common side effect of radiation therapy.  Endurance, stamina, concentration, and motivation may all decreased as a result of fatigue.  Conserve your energy and rest when you need to.  Eat a well-balanced diet and stay well-hydrated by drinking plenty of water.  Exercise such as walking or yoga can improve your energy.  Respect your body’s limitations – if you hurt while exercising, stop.

  • Bowel Irritation

    Abdominal cramping, frequent bowel movements, loose stools, gas or diarrhea may occur 2 – 4 weeks after treatments have begun.  If you experience the above symptoms, a low-fiber diet is recommended; this involves avoiding fresh fruits and vegetables, whole grains (bran), nuts, and seeds.  Your nurse has a written copy of the low-fiber diet instructions.  Medication may also be used to relieve these symptoms.   Please discuss these symptoms with your doctor or nurse

  • Nutrition:

    During your course of therapy, it is very important to maintain your weight.  We suggest a diet high in protein and healthy fats.  Your nurse will be checking your weight frequently.  We can suggest food supplements if weight loss occurs.  It is not unusual to notice a decrease in appetite during radiation therapy.  You will need to make a conscious effort to maintain an adequate calorie intake.  Frequent, small meals (every 2-3 hours) may be tolerated better than three large meals a day.

  • Duration

    Side effects may worsen the final week of treatment and the week after radiation treatments are completed. Most of these side effects gradually subside within 4-8 weeks after treatment. Please call our office if you have any questions at any time during or after your radiation treatments.

For questions to ask your provider, see our FAQ page.