Colon cancer like many cancers, when small does not produce any symptoms. Since it is deep inside, it cannot be seen or visualised by patient himself. Only when it grows to a certain size, the tumour leads to a bleeding or difficulty in passage of stools or altered bowel habits. When the secondaries occur in liver or elsewhere (metastasis) symptoms develop accordingly. The detection happens when a colonoscopy is done for screening or some symptoms occur.
If there is a family history of colon cancers the screening must be done in those people every year or at least alternate year. People must watch out for symptoms of change in bowel habits – recent onset of constipation, or diarrhoea alternating with constipation or bleeding in stools, or black coloured stools.
Colon cancer was not that common in India as traditional diet consisted of good roughage. Current diet pattern has changed to more western and less roughage leading to increasing incidence of colon cancers. Having considerable fresh vegetables, fruits, less of meat and processed meat, whole cereals are ways to prevent colon cancer.