How Often Does Rectal Bleeding Indicate Colorectal Cancer?

A.D. Walling

Rectal bleeding is a relatively common symptom encountered in primary care. Although the risk of colorectal cancer is believed to be low, this rarely has been studied in patients presenting to primary care physicians. Four studies in European countries reported cancer rates of 2.4 to 7.0 percent.
The British National Institute for Health and Clinical Excellence guidelines advise that patients older than 40 years with six weeks of rectal bleeding and loose stools should be tested for colorectal cancer. Du Toit and colleagues carried out a prospective study in a rural English practice of four doctors (with an average yearly patient list of 4,426) over 10 years to establish the risk of colorectal cancer in patients presenting with rectal bleeding.
Beginning in 1993, all patients older than 45 years who presented with rectal bleeding were tested and monitored for outcomes. The testing was done by sigmoidoscopy, barium enema, or colonoscopy. A computer search each year for all patients undergoing one of these tests was used to verify that all eligible patients in the practice had been included in the study.
During the study, 265 patients presented with new-onset rectal bleeding (see accompanying table). Colorectal cancer was diagnosed in 15 of these patients, and 13 had adenomas. A new episode of rectal bleeding in a patient 45 years or older had a positive predictive value for colorectal cancer of 5.7 percent (4.9 percent for adenoma). The authors calculate that one out of 10 patients with new rectal bleeding had neoplastic changes. Only two of the patients with bleeding and colorectal cancer also reported loose stools.
During the study, an additional 23 patients were diagnosed with colorectal cancer, and 20 were diagnosed with adenoma but had no rectal bleeding. The authors conclude that about one out of 10 patients who present to a family physician because of rectal bleeding has colorectal cancer or adenoma. Because factors such as age and change in bowel habit do not appear to help identify patients at increased risk of neoplasia, the authors believe that all patients 45 years and older should be tested for malignancy if they have rectal bleeding.
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Hemorrhoids

What are hemorrhoids?
Hemorrhoids are swollen veins in your rectum or anus. The type of hemorrhoid you have depends on where it occurs. Internal hemorrhoids involve the veins inside your rectum. Internal hemorrhoids usually don't hurt but they may bleed painlessly. Sometimes, an internal hemorrhoid may stretch down until it bulges outside your anus. This is called a prolapsed hemorrhoid. A prolapsed hemorrhoid will go back inside your rectum on its own, or you can gently push it back inside.
External hemorrhoids involve the veins outside the anus. They can be itchy or painful and can sometimes crack and bleed. If a blood clot forms, you may feel a tender lump on the edge of your anus. You may see bright red blood on the toilet paper or in the toilet after a bowel movement.

What causes hemorrhoids?
One of the main causes is straining when you're trying to have a bowel movement. This may happen if you're constipated or if you have diarrhea. It may also happen if you sit on the toilet too long.

Who gets hemorrhoids?
Just about everyone has hemorrhoids at some time. But some things may make you more likely to get them. People whose parents had hemorrhoids may be more likely to get them. Pregnant women often get hemorrhoids because of the strain from carrying the baby and from giving birth. Being very overweight, or standing or lifting too much can make hemorrhoids worse.

Should I see my family doctor?
See your doctor if you notice bleeding to make sure the cause is hemorrhoids and not some other problem.

What can I do about hemorrhoids?
Preventing constipation

• Include more fiber in your diet. Fresh fruits, leafy vegetables, and whole-grain breads and cereals are good sources of fiber.
• Drink plenty of fluids (except alcohol). Eight glasses of water a day is ideal.
• Exercise regularly.
• Avoid laxatives except bulk-forming laxatives such as Fiberall, Metamucil, etc. Other types of laxatives can lead to diarrhea, which can worsen hemorrhoids.
• When you feel the need to have a bowel movement, don't wait too long to use the bathroom.
  

Constipation is a main cause of hemorrhoids.
In the meantime, you can follow the tips to reduce the pain caused by hemorrhoids. Don't use hemorrhoid medicine without talking to your family doctor first.

Relieving the pain

• Take warm soaks 3 or 4 times a day.
• Clean your anus after each bowel movement by patting gently with moist toilet paper or moistened pads such as baby wipes.
• Use ice packs to relieve swelling.
• Use paracetamol/ acetaminophen, ibuprofen or aspirin to help relieve pain.
• Apply a cream that contains witch hazel to the area or use a numbing ointment. Creams that contain hydrocortisone can be used for itching or pain.
  

Most painful hemorrhoids stop hurting on their own in 1 to 2 weeks. If yours keep causing problems, talk with your family doctor about your options. Internal hemorrhoids can also be destroyed by injecting them with chemicals or by burning them.
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