What are the early symptoms of rectal cancer?

Early Symptoms of Rectal Cancer

The most common early symptoms of rectal cancer are hematochezia (rectal bleeding), change in bowel habits, and abdominal pain. These symptoms should prompt immediate diagnostic evaluation, particularly in individuals over 45 years of age 1.

Key Early Symptoms

Primary Warning Signs

• Rectal bleeding (hematochezia):

  • Most common symptom (46-50% of cases) 1
  • Strongest association with rectal cancer diagnosis 1
  • Confers a hazard ratio of 10.66 for early-onset colorectal cancer 1
  • More common in rectal cancer than colon cancer 1
  • Dark red rectal bleeding has >95% specificity for colorectal cancer 1

• Change in bowel habits:

  • Present in approximately 38-42% of cases 1, 2
  • Associated with 3.33 times higher odds of finding colorectal cancer 3
  • May include diarrhea, constipation, or alternating patterns

• Abdominal pain/discomfort:

  • Present in approximately 32-40% of cases 1, 2
  • Often nonspecific but should not be dismissed, especially when combined with other symptoms

Additional Warning Signs

• Iron deficiency anemia:

  • Present in approximately 13% of cases 1
  • Confers a hazard ratio of 10.81 for early-onset colorectal cancer 1
  • Often associated with occult bleeding

• Unexplained weight loss:

  • Present in approximately 10% of cases 1
  • Weight loss ≥5 kg (>11 pounds) within 5 years associated with higher odds of early-onset colorectal cancer (OR 2.23) 1

• Other symptoms:

  • Abdominal distention
  • Fatigue (though this symptom alone is associated with decreased likelihood of cancer) 3
  • Anorectal stimulating symptoms (tenesmus, feeling of incomplete evacuation)

Important Clinical Considerations

Symptom Patterns and Risk Assessment

1. Multiple symptoms increase risk:

   • Presence of 1 red-flag symptom: 1.9-fold increased risk
   • Presence of 2 red-flag symptoms: 3.6-fold increased risk
   • Presence of 3+ red-flag symptoms: 6.5-fold increased risk 1

2. Age considerations:

   • Age >50 years with symptoms significantly increases risk (aOR 3.00) 3
   • Early-onset rectal cancer (before age 50) is increasing in incidence 1
   • Symptoms in younger patients (<45 years) should not be dismissed 1

Diagnostic Delays and Pitfalls

• Patients with rectal cancer often experience longer delays in diagnosis (152 vs 87 days) compared to later-onset colorectal cancer 1
• Symptoms may be misattributed to benign conditions, particularly in younger patients 1
• Patients with change in bowel habits are less likely to seek prompt medical attention (25.3%) compared to those with other symptoms (52.0%) 2
• Abdominal pain and changes in bowel habits are common and nonspecific, requiring careful clinical judgment 1

Recommended Diagnostic Approach

For patients presenting with any of the above symptoms, especially rectal bleeding, change in bowel habits, or unexplained weight loss:

1. Immediate colonoscopy is the recommended diagnostic procedure 1

   • Should be complete to the cecum and of high quality
   • Provides direct visualization and opportunity for biopsy

2. Do not use FIT (fecal immunochemical test) for symptomatic patients as it may delay diagnosis 1

3. CT scan if perforation or obstruction is suspected 1

Early detection significantly improves outcomes, with 5-year survival rates of 83% for Dukes' A (confined to bowel wall) versus 64%, 38%, and 3% for Dukes' B, C, and D respectively 1. Patients presenting with rectal bleeding tend to have earlier stage disease and better 5-year survival (54.8%) compared to those with change in bowel habits or abdominal pain alone (40.9%) 4.