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What is rectal cancer: symptoms, causes and risk factors

by Dr. Cristi Blajut
rectal cancersymptomsrisk factorspreventionearly diagnosis

What is rectal cancer — anatomical illustration

Rectal cancer is a malignant tumor that develops in the last 15 centimeters (6 inches) of the large intestine, between the sigmoid colon and the anal canal. Although often grouped together with colon cancer under the term “colorectal cancer”, rectal cancer has distinct features in terms of diagnosis, treatment and recovery.

Colorectal cancer is among the most common causes of cancer death, and the number of cases diagnosed continues to rise. Understanding the symptoms and risk factors can make the difference between an early-stage diagnosis, when chances of cure exceed 90%, and a late one.

Rectal cancer symptoms

Rectal cancer symptoms can be subtle at first and are often confused with benign conditions such as hemorrhoids. For this reason, any persistent symptom deserves medical investigation.

Warning signs

  • Rectal bleeding — red or dark blood in stool, on toilet paper or in the toilet bowl
  • Change in bowel habits — constipation, diarrhea or alternating between them, lasting more than 4 weeks
  • Sense of incomplete evacuation — after defecation, you feel that the bowel hasn’t fully emptied
  • Narrow stools — “pencil-thin” stools, narrower than usual
  • Abdominal or rectal pain — cramps, discomfort or pain in the pelvic area
  • Unexplained weight loss — losing weight without dieting or exercise
  • Chronic fatigue — caused by anemia from chronic blood loss

When to see a doctor

See a doctor if any of these symptoms persist for more than 2-3 weeks. Don’t assume that rectal bleeding is caused by hemorrhoids without medical evaluation. Early diagnosis saves lives.

Causes of rectal cancer

Rectal cancer occurs when cells in the rectal lining undergo genetic mutations that cause them to multiply uncontrollably. In most cases, the process starts as an adenomatous polyp — a benign growth that, over time (usually 10-15 years), can transform into cancer.

The factors that trigger these mutations are multiple and include both genetic predisposition and environmental and lifestyle factors.

Main risk factors

Non-modifiable factors

  • Age over 50 — risk rises significantly after this age, although cases in younger patients are increasing
  • Family history — increased risk if a first-degree relative (parent, sibling, child) has had colorectal cancer
  • Genetic syndromes — Lynch syndrome (HNPCC) and familial adenomatous polyposis (FAP) dramatically increase risk
  • Personal history of polyps — patients who have had adenomatous polyps have an increased risk of new polyps and cancer
  • Inflammatory bowel disease — ulcerative colitis and Crohn’s disease increase risk after 8-10 years of active disease

Modifiable factors

  • Diet — high consumption of red and processed meat, low in fiber, fruit and vegetables
  • Sedentary lifestyle — lack of regular physical activity
  • Obesity — high body mass index, especially abdominal obesity
  • Smoking — increases the risk of polyps and colorectal cancer
  • Excess alcohol — more than 2 alcoholic drinks per day
  • Type 2 diabetes — associated with increased risk independent of obesity

How rectal cancer can be prevented

Prevention rests on two complementary strategies:

Regular screening

  • Colonoscopy is the gold standard for early detection — recommended starting at age 45 (or earlier with risk factors)
  • Fecal occult blood test (FOBT/FIT) — yearly, as an alternative to colonoscopy
  • If you have a family history, screening should start 10 years before the age at which the relative was diagnosed

Lifestyle

  • Diet rich in fiber, fruit, vegetables and whole grains
  • Moderate physical activity at least 150 minutes per week
  • Maintain a healthy body weight
  • Limit red and processed meat
  • Quit smoking
  • Moderate alcohol consumption

Conclusion

Rectal cancer detected at an early stage has cure rates of over 90%. Knowing the symptoms and risk factors is the first step toward timely diagnosis. Don’t ignore persistent digestive symptoms, and talk to your doctor about the screening schedule appropriate for your age and medical history.

This article is for informational purposes only and does not replace medical consultation. For diagnosis and treatment, please consult a specialist.