Colorectal Cancer Symptoms

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By Dr Ananya Mandal, MD

Colorectal cancer or bowel cancer in its early stages may have no symptoms. Symptoms depend on stage of the tumor, the location and spread of the tumor.

Initial symptoms:

Bleeding in stools or blood streaks on stools. This may be bright red or plum-coloured. This is the most commonly noticed symptom and should never be ignored.
Mucus secretion with stools.
A change in normal bowel habits with diarrhea or constipation that persists for more than three weeks.
Abdominal pain.
Persistent pain in and around the anus.
Abdominal bloating.
Loss of appetite.
Unexplained weight loss.
Problems may often be confused with piles or haemorrhoids, irritable bowel syndrome and inflammatory bowel conditions like Crohn’s disease, Ulcerative colitis etc.

Symptoms of more advanced bowel cancer

Over time the symptoms usually worsen. The symptoms of more advanced stages of bowel cancer include those seen in initial stages and:

Severe weakness
Anemia – this is due to lower numbers of red blood cells in blood. Anemia may result when there is severe bleeding within the tumors. Anemia may lead to fatigue, pallor and breathlessness.
Obstruction in the bowel - this may lead to bloating and pain usually around the navel, constipation and vomiting, non-passage of flatus and severe distress. This is an emergency condition and needs immediate medical attention.
Spread of the cancer to the liver shows up as liver enlargement or hepatomegaly and jaundice. In advanced cases there may be collection of fluids within the abdominal cavity or ascitis. 20-25% of patients have clinically detectable liver spread of the cancer at the time of the initial diagnosis and a further 40-50% of patients develop liver metastases within three years of primary treatment using surgery.
There may be rare complications as initial symptoms of an advanced cancer. These include gastrocolic fistula, ischiorectal or perineal abscesses and deep vein thrombosis.

Local and generalized symptoms

Symptoms of colorectal cancer may also be classified as local or more generalized:

Local symptoms of the cancer are more likely if the tumor is located closer to the anus. This includes symptoms like change in bowel habits, and a feeling of incomplete defecation (a symptom termed tenesmus). There is a significant reduction in diameter of stool. Both tenesums and change in shape of stool is indicative of a rectal cancer. In addition there is bleeding and passage of mucus and pain around the anus.
Generalized symptoms are caused due to chronic bleeding that leads to iron deficiency anemia, fatigue, palpitations and noticed as pallor. There may be weight loss, fever, loss of appetite and deep vein thrombosis as additional symptoms. Symptoms of involvement of other organs like liver, lungs, brain and bone are also generalized in nature.

Reviewed by April Cashin-Garbutt, BA Hons (Cantab)