From the Guidelines
Most colorectal cancers initially present with changes in bowel habits, including persistent diarrhea or constipation, narrowing of stool, rectal bleeding or blood in the stool, abdominal pain or cramping, unexplained weight loss, and feelings of incomplete bowel emptying. As the disease progresses, patients may experience fatigue due to anemia from chronic blood loss, weakness, and decreased appetite. Some patients may present with a palpable abdominal mass, especially with right-sided colon cancers. It's essential to note that early-stage colorectal cancer is often asymptomatic, which is why screening is crucial for early detection. The symptoms develop gradually as the tumor grows and begins to obstruct the bowel lumen or invade surrounding tissues. Right-sided colon cancers tend to present later with anemia and fatigue, while left-sided tumors more commonly cause changes in bowel habits and rectal bleeding due to the narrower lumen of the left colon. Any persistent change in bowel habits lasting more than two weeks, especially in individuals over 50, should prompt medical evaluation, as suggested by the most recent guidelines 1.
Key Symptoms
- Changes in bowel habits (persistent diarrhea or constipation, narrowing of stool)
- Rectal bleeding or blood in the stool (which may appear bright red or dark/tarry)
- Abdominal pain or cramping
- Unexplained weight loss
- Feelings of incomplete bowel emptying
- Fatigue due to anemia from chronic blood loss
- Weakness and decreased appetite
Importance of Screening
Screening is crucial for early detection of colorectal cancer, as early-stage disease is often asymptomatic. The most recent guidelines emphasize the importance of screening and prompt evaluation of symptoms, especially in individuals over 50 1.
Location and Symptoms
The location of the tumor can influence the symptoms presented. Right-sided colon cancers tend to present later with anemia and fatigue, while left-sided tumors more commonly cause changes in bowel habits and rectal bleeding due to the narrower lumen of the left colon, as noted in the guidelines 2.
Medical Evaluation
Any persistent change in bowel habits lasting more than two weeks, especially in individuals over 50, should prompt medical evaluation, including colonoscopy or flexible sigmoidoscopy, as recommended by the guidelines 1.
From the Research
Common Symptoms of Colorectal Cancer
The most common symptoms of colorectal cancer include:
- Rectal bleeding (58%) 3
- Abdominal pain (52%) 3
- Change in bowel habits (51%) 3
- Anemia (57%) 3
- Occult bleeding (77%) 3
Association Between Symptoms and Colorectal Cancer
Studies have shown that:
- Rectal bleeding is associated with colorectal cancer (AUC 0.66; LR+ 1.9; LR- 0.7) 4
- Weight loss is associated with colorectal cancer (AUC 0.67, LR+ 2.5, LR- 0.9) 4
- There is no significant association between colorectal cancer and symptoms such as change in bowel habit, constipation, diarrhea, or abdominal pain 4
Differences in Symptom Presentation Between Proximal and Distal Colon Cancer
Research has found that: