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Constipation and Cancer: How are they connected?

Overcome constipation with consistent effort and a little discipline.

Chemo And Constipation

"If you concentrate on small, manageable steps you can cross unimaginable distances.” ― Shaun Hick

The range of normal bowel movements (BMs) in healthy people is normally defined as three BMs per day to three per week.

Constipation or trouble passing stool, either caused by surgery, chemotherapy, pain drugs, or other medical issues, can begin as an unpleasant feeling and quickly increase into a painful experience.

The way you handle it is determined by the type of constipation you have.

The condition is relative, pertaining to a change in a person's typical bowel movement.

The frequency of bowel movements might range from once or twice each day to once every two days.

The "four toos" comprise stools that may be too rigid, too tiny, too tough to evacuate, and too irregular, according to one description.

Constipation is reported by nearly 50% of patients receiving chemotherapy.


Factors adding to constipation may include disruption of healthy intestinal motility, excessive dryness of stool content, reduced perception of rectal swelling with loss of urge to excrete, and harmful of the tone of the rectum.

The stool grows dryer the more it stays in the colon. Constipated stools can vary change in size from little, hard "rock formations" to large, dense masses, and they can be connected with considerable pain or depression.

Other connected symptoms may include abdominal distention and bloating, inability to urinate, nausea, loss of appetite, and rectal problems including hemorrhoids and anal fissures. Constipation can also cause paradoxical or overflow diarrhea, as liquid stool passes around the obstructing constipated stool.

Chronic constipation can also lead to larger problems including fecal impaction, especially in patients with advanced cancer who have poor oral intake with little dietary fiber, dehydration, limited physical activity or immobility, or obstruction due to mass effect of the tumor itself.

Constipation is the third most common symptom (after pain and anorexia) in those with advanced cancer.

Constipation is very frequent among people with cancer, with about 60% of them experiencing it.

The incidence increases in patients with advanced cancer, especially in those receiving certain pain medications including pain-relieving drugs such as codeine, morphine, fentanyl, or medications with anticholinergic properties such as atropine.

Opioid drugs cause constipation by inhibiting gastric emptying and peristalsis in the gastro-intestinal tract which results in delayed absorption of medications and increased absorption of fluid. Constipation and stool hardness are caused by inadequate liquid in the colon.

Other medications including iron supplements, certain chemotherapy drugs, and anti-seizure medications can also cause impaired bowel movements.

Apart from medications, cancer patients can also be constipated due to:

  • Surgery-related scarring or adhesions can constrict or partly obstruct your bowels.

  • Cancer in the stomach causes a lack of appetite or obstructs the passage of food.

  • A tumor that partially or completely blocks the small or large intestine.

  • Cancer exerts a mass effect against the nerves in the spinal canal.

  • Abnormally high calcium levels in the blood cause dehydration which in turn causes constipation.

  • Potassium deficiency can affect the muscles in the intestines, slowing the passage of food and waste.

  • Thyroid gland harmful (hypothyroidism) where too little thyroid hormone is produced in the body can slow down your body’s functions including bowel movements.

  • Long standing diabetes damages the nerves that control the function of the stomach and intestines resulting in constipation.

If your symptoms are unusual or worsening, it is important you seek medical advice.

Chronic constipation can indicate a more serious condition, warranting additional testing.

Talking to your cancer care providers is the best approach to prevent or treat this condition, however, there are simple preventative measures that can become part of your daily routine and can be helpful during and after treatment.

Here are a few recommendations for treating or preventing constipation:

  • Establish mealtimes and stick to them.

  • Because digestion starts inside the mouth, sit down and concentrate on your meal, chewing deliberately and completely.

  • Have a bowel movement around the same time more often if possible. It could take a while, but if you're really persistent, your system will adjust.

  • Slowly try to increase the amount of fibre in your diet and eat naturally high fiber foods such as lightly steamed vegetables and salads, lentils, raisins, fruits such as prunes, dried apricots and whole grains. While you're on treatment, avoid raw fruits and veggies since they can be hard to process.

  • If you raise your fiber intake, you must also raise your fluid intake accordingly. Prior to actually adding fiber to your meals, if you have an ostomy or have had intestinal surgery, speak with your medical healthcare professional.

  • Try to drink at least eight to ten glasses of warm or room temperature water daily. If you choose, you can flavour the water with lemon, lime, or mint.

  • Limit yourself to one caffeinated beverage in a day. Caffeine dehydrates the body, making constipation worse.

  • Avoid processed foods as often as feasible.

  • Make an effort to exercise every day. Improving your bowel function can be as simple as walking for thirty minutes a day at a rate that is acceptable for you.

  • There is a great yoga pose that can help with bowel movements, it is called Malasana or the garland pose. Malasana tones the abdominal muscles and stimulates the function of the large intestine to help with elimination. Begin cautiously, be regular, and pay heed to how your body is feeling at all times. This position is not for you if you have knee ailments or problems.

  • Use a squatting seat, which fits alongside your toilet and lifts your feet, transforming your "sitting" stance into a "squatting" position. By resting the puborectalis muscle and straightening your big intestine, you can make it easier to eliminate waste.

  • Lastly, any over-the-counter meds including laxatives, stool softeners, suppositories or enemas should be taken only after talking to your physician.

Chemo And Constipation

Despite its clinical impact, constipation is both poorly recognized and poorly treated. It causes significant distress in the patient and can affect their day-to-day living and their mood in a profound manner.

Untreated constipation places a burden on the patient and the caregiver and results in a higher risk of hospitalization.

Prevention of constipation, screening for its presence and early intervention can reduce both patient distress and care costs.

Your cancer care team may recommend certain tests including a rectal exam, abdominal x-ray or blood work to make sure they have the right cause for your constipation.

In other cases, opioid pain medications are a proven cause of constipation so tests may not be needed.

Your doctor may ask about your bowel movements and how much they've changed, as well as what medications you are consuming, your diet, and any other conditions you may have.

Constipation And Cancer

Here are some questions that can help you talk about constipation with your cancer care team:

  • What is the most likely cause of my constipation?

  • What types of tests will I require, and how should I plan for them?

  • Am I at risk of complications related to constipation?

  • What treatment do you recommend?

  • How much fluid should I drink every day?

  • Should I take over-the-counter treatments for constipation such as, for example, Miralax, Milk of Magnesia, Metamucil, Colace etc.?

  • Which OTC product is best for me based on my symptoms?

  • Are there any dietary restrictions that I need to follow?

Reason to hope: In patients with metastatic colorectal cancer who had the BRAF V600E mutation, a triple medication combination of encorafenib, cetuximab, and binimetinib led to a significantly extended survival rate and a higher response rate than conventional therapies.

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Reason to Hope

There is new research from Brigham and Women’s Hospital that indicates a Western-style diet that is rich in red and processed meat, sugar and refined grains/carbohydrates is tied to higher risk of colorectal cancer through the intestinal microbiota.  Gastroenterology, 2022;DOI:10.1053/j.gastro.2022.06.054 

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