Recognizing the Signs and Symptoms of Colorectal Cancer What You Need to Know

Colorectal cancer (CRC) is one of the most common cancers worldwide, yet many people remain unaware of its early signs and symptoms (Morgan et al., 2022). Colorectal cancer is now the leading cause of cancer-related death among people under 50 in the United States, according to new evidence from the American Cancer Society (Siegel et al., 2025). Detecting CRC early can significantly improve treatment outcomes and survival rates. This post explains the key symptoms to watch for, how CRC is diagnosed, and what makes early onset colorectal cancer different. Understanding these signs can help you take timely action and seek medical advice when needed.

Medical imaging scan highlighting colorectal area

How Colorectal Cancer Is Diagnosed

Colorectal cancer can be found in two main ways: after symptoms appear or through routine screening in people without symptoms. Screening tests like colonoscopy, stool tests, or imaging scans can detect cancer early, sometimes even before symptoms develop. Some cases are discovered incidentally when imaging is done for other reasons.

When symptoms do appear, they often prompt further investigation. In some cases, people may be admitted to the hospital urgently due to complications such as intestinal obstruction, perforation, or severe gastrointestinal bleeding. These emergencies highlight the importance of recognizing symptoms early.

Symptoms and Signs of Colorectal Cancer

Symptoms of colorectal cancer vary depending on the tumor’s location and size. Some signs are more typical and should raise suspicion, while others are less common but still important to note. Here are signs and symptoms of colorectal cancer according to research (Demb et al., 2024, Hamilton et al., 2005, Speights et al., 1991, Steinberg et al., 1986)

• Hematochezia or melena: This means visible blood in the stool or black, tarry stools caused by bleeding in the digestive tract.

• Abdominal pain: Persistent or unexplained pain in the abdomen can indicate a tumor pressing on surrounding tissues.

• Iron deficiency and iron deficiency anemia: Unexplained anemia may result from chronic blood loss in the intestines.

• Change in bowel habits: This includes diarrhea, constipation, or a change in stool consistency or frequency that lasts for several weeks.

• Abdominal distension: Swelling or bloating of the abdomen may suggest obstruction.

• Nausea and vomiting: These symptoms can occur if the tumor causes a blockage in the intestines.

• Weight loss and loss of appetite: These are signs of advanced disease but can also appear earlier.

• Tenesmus (a feeling of incomplete bowel emptying)

• Fatigue

• Abdominal mass

• Rectal pain

  
  

Recognizing these symptoms early and consulting a healthcare provider can lead to timely diagnosis and treatment.

Diagram of digestive system focusing on colon and rectum

When to Seek Medical Advice

If you notice any of the symptoms described, especially blood in your stool or a persistent change in bowel habits, do not ignore them. Early detection of colorectal cancer can save lives. Your healthcare provider may recommend screening tests or further investigations based on your symptoms and risk factors. Always talk with a healthcare professional about your symptoms and screenings.

Emergency symptoms such as severe abdominal pain, vomiting, or signs of intestinal obstruction require immediate medical attention. If you don't feel well seek medical attention!

Hospital emergency room entrance with ambulance bay

Final Thoughts

Colorectal cancer often develops silently but can show clear signs once the tumor grows. Knowing the symptoms and acting quickly can make a significant difference. Routine screening remains the best way to catch CRC early, especially for those over 45 or with a family history. For younger individuals, awareness of early onset symptoms is crucial.

If you experience any suspicious symptoms or have concerns about your risk, talk to your healthcare provider. Early diagnosis leads to better treatment options and improved outcomes. Stay informed, stay vigilant, and prioritize your health.

Link to article: How to protect yourself from colon cancer

References:

1. Demb J, Kolb JM, Dounel J, Fritz CDL, Advani SM, Cao Y, Coppernoll-Blach P, Dwyer AJ, Perea J, Heskett KM, Holowatyj AN, Lieu CH, Singh S, Spaander MCW, Vuik FER, Gupta S. Red Flag Signs and Symptoms for Patients With Early-Onset Colorectal Cancer: A Systematic Review and Meta-Analysis. JAMA Netw Open. 2024 May 1;7(5):e2413157.

2. Hamilton W, Round A, Sharp D, Peters TJ. Clinical features of colorectal cancer before diagnosis: a population-based case-control study. Br J Cancer. 2005 Aug 22;93(4):399-405. doi: 10.1038/sj.bjc.6602714. PMID: 16106247; PMCID: PMC2361578.

3. Morgan E, Arnold M, Gini A, Lorenzoni V, Cabasag CJ, Laversanne M, Vignat J, Ferlay J, Murphy N, Bray F. Global burden of colorectal cancer in 2020 and 2040: incidence and mortality estimates from GLOBOCAN. Gut. 2023 Feb;72(2):338-344.

4. Siegel RL, Wagle NS, Jemal A. Leading Cancer Deaths in People Younger Than 50 Years. JAMA. Published online January 22, 2026.

5. Speights VO, Johnson MW, Stoltenberg PH, Rappaport ES, Helbert B, Riggs M. Colorectal cancer: current trends in initial clinical manifestations. South Med J. 1991 May;84(5):575-8.

6. Steinberg SM, Barkin JS, Kaplan RS, Stablein DM. Prognostic indicators of colon tumors. The Gastrointestinal Tumor Study Group experience. Cancer. 1986 May 1;57(9):1866-70.