What is the characteristic odor associated with colorectal (colon) cancer?

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Last updated: April 29, 2025View editorial policy

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From the Guidelines

Colon cancer itself does not have a specific smell that people can detect, but advanced colon cancer may cause changes in stool odor due to alterations in the digestive process, such as bleeding, mucus production, or changes in gut bacteria. These changes can affect stool composition and smell, and may be accompanied by other symptoms that should prompt medical attention, including persistent changes in bowel habits, blood in stool, unexplained weight loss, fatigue, and abdominal pain or discomfort 1. The American Cancer Society estimates that over 140,000 Americans are expected to be diagnosed with colorectal cancer in 2018, and that the disease is the second leading cause of cancer death, leading to over 50,000 deaths annually 1.

Risk Factors and Diagnosis

Risk factors for colorectal cancer include family history, familial adenomatous polyposis (FAP) and attenuated FAP (AFAP) syndromes, hereditary non-polyposis colorectal cancer (HNPCC) syndrome, past history of colorectal cancer or adenoma, chronic ulcerative colitis and Crohn’s disease 1. Diagnosis of colon cancer requires histopathologic confirmation, and staging provides essential prognostic information relevant for choosing adequate therapy 1.

Symptoms and Evaluation

Symptoms that should prompt medical attention include persistent changes in bowel habits, blood in stool, unexplained weight loss, fatigue, and abdominal pain or discomfort. If you notice persistent changes in stool odor along with other concerning symptoms, consult a healthcare provider promptly for proper evaluation, which typically includes physical examination, blood tests, and possibly colonoscopy for definitive diagnosis. While some research has explored using specially trained dogs or electronic "nose" devices to detect volatile organic compounds associated with cancer, these methods are still experimental and not used in standard clinical practice 1.

Treatment and Prevention

Adjuvant chemotherapy is recommended for stages T1–4, N1–2, M0 (i.e. stage III, modified Dukes C1–3), and may be considered in selected node-negative patients, especially if high-risk factors for recurrence are found 1. Standard adjuvant treatment consists of fluoropyrimidine-based chemotherapy, which has been shown to result in a statistically significant survival benefit 1. Lifestyle modifications, such as a healthy diet, regular physical activity, and avoidance of tobacco and excess alcohol, can also help reduce the risk of colorectal cancer 1.

From the Research

Colon Cancer Smell

  • There is no direct evidence in the provided study to suggest a specific smell associated with colon cancer [ 2 ].
  • The study focuses on the use of antibiotics in colorectal surgery and their effectiveness in reducing wound infection rates [ 2 ].
  • It discusses the tissue concentrations of ciprofloxacin in colon, peritoneum, muscle, subcutaneous fat, and skin, but does not mention any specific odors related to colon cancer [ 2 ].
  • The study's findings are related to the reduction of wound infection rates and the effectiveness of ciprofloxacin in colorectal surgery, but do not provide information on colon cancer smell [ 2 ].

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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