Colorectal Cancer Symptoms That Should Not Be Ignored

Colorectal cancer can affect the colon or rectum. In Singapore, it remains a condition of concern, especially among adults aged 50 and above. The Singapore Cancer Society notes that people aged 50 and above have a higher risk of colorectal cancer, while HealthHub advises that symptoms such as blood in stools or changes in bowel habits should be assessed even if a previous FIT result was normal.

While some people may not experience symptoms in the early stages, certain changes in bowel habits, bleeding, pain, or unexplained physical changes may require medical review. Recognising these symptoms does not mean assuming cancer is present. Rather, it helps patients know when to seek assessment and avoid delaying care.

Blood in the Stool or Rectal Bleeding

Blood in the stool is one symptom that should be checked by a doctor. It may appear as bright red blood, darker blood, or stool that looks unusually dark. Rectal bleeding may be caused by several conditions, including haemorrhoids, anal fissures, inflammation, polyps, or colorectal cancer.

The Singapore Cancer Society states that having blood in the stool may be a sign of colorectal cancer, while NUH lists blood in the stools as one of the warning symptoms that may alert doctors to look out for colorectal cancer.

Patients should not assume that bleeding is due to piles without medical assessment, especially if it persists, recurs, or is accompanied by other symptoms.

Persistent Changes in Bowel Habits

A change in bowel habits may include constipation, diarrhoea, narrower stools, a change in stool frequency, or a feeling that the bowel has not emptied completely. Occasional bowel changes can happen due to diet, hydration, stress, medication, or infection. However, changes that persist may require further assessment.

HealthHub advises patients to see a doctor immediately if colorectal cancer symptoms such as changes in bowel habits develop, even after a normal FIT result.

This is particularly relevant if bowel changes occur together with rectal bleeding, abdominal discomfort, weight loss, or fatigue.

Abdominal Pain or Discomfort

Abdominal pain, cramps, bloating, or discomfort may be caused by many digestive conditions. However, unexplained or persistent abdominal pain should not be dismissed, especially if it occurs with bowel changes or blood in the stool.

NUH lists unexplained abdominal pain among the warning symptoms for colorectal cancer, while KKH notes that tummy pain or discomfort may be one of the symptoms that should prompt medical review.

A doctor may recommend further assessment depending on the patient’s symptoms, age, family history, and other risk factors.

Unexplained Weight Loss

Unexplained weight loss can occur for different reasons and may be related to digestive, hormonal, metabolic, or cancer-related conditions. When weight loss happens without changes in diet, activity level, or intentional weight management, medical review is advisable.

Maven Surgery’s colorectal cancer information page lists weight loss among symptoms that may be associated with colorectal cancer.

Weight loss should be assessed in context, particularly when it occurs with bowel changes, bleeding, tiredness, or reduced appetite.

Fatigue or Unexplained Anaemia

Persistent fatigue may have many causes, including lack of sleep, stress, nutritional deficiencies, chronic illness, or anaemia. In colorectal cancer, bleeding from the bowel may sometimes contribute to iron-deficiency anaemia, which can cause tiredness, weakness, dizziness, or shortness of breath.

NUH includes unexplained anaemia among warning symptoms that may alert doctors to check for colorectal cancer.

Patients with persistent fatigue or anaemia should seek medical assessment to identify the underlying cause.

A Lump or Mass in the Abdomen

A lump or mass in the abdomen should be assessed by a doctor. While it may be caused by different conditions, it should not be ignored, especially if it is associated with pain, bloating, bowel changes, bleeding, or weight loss.

NUH lists abdominal mass among warning symptoms linked to colorectal cancer evaluation, and KKH also notes tummy lump as a symptom that should prompt medical review.

Medical evaluation may involve physical examination, blood tests, imaging, colonoscopy, or referral to a specialist, depending on the findings.

Colorectal Cancer Can Have No Symptoms in the Early Stages

One reason screening is discussed for colorectal cancer is that early disease may not always cause obvious symptoms. NUH notes that colorectal cancer can be a “silent” disease in the early stages, while SingHealth states that screening is recommended from age 50 for individuals with no symptoms, with earlier screening advised for those with a family history of colorectal cancer.

In Singapore, FIT screening is commonly discussed for eligible individuals. The Singapore Cancer Society describes FIT as a test that can help detect blood in stool and notes that it is done once a year. HealthHub also states that FIT screening should be done once a year.

When to See a Doctor

Patients should consider medical review if they notice:

• Blood in the stool or rectal bleeding
• Persistent constipation, diarrhoea, or changes in bowel habits
• Unexplained abdominal pain or discomfort
• Unexplained weight loss
• Persistent fatigue or anaemia
• A lump or mass in the abdomen
• Abnormal stool test or screening results

These symptoms do not confirm colorectal cancer, but they may require further investigation. A doctor may advise stool testing, blood tests, colonoscopy, imaging, or referral for specialist assessment depending on the patient’s condition.

A Brief Note on Specialist Assessment

For patients in Singapore who require specialist review, a colorectal surgeon like Dr Chong Chee Keong of Maven Surgery in Singapore, may be involved in assessing symptoms, reviewing colonoscopy findings, and discussing treatment options when needed.