Colonic / rectal cancer is one of the commonest cancers seen all over the world. The incidence is on the rise in India. It is one of the few malignancies where long term survival is possible even in advanced stage of detection. Hence it is very important for all the patients with this disease to understand various aspects of this disease.
There is no specific cause for colorectal cancer except for de novo genetic changes leading to cancer, polyposis syndromes (cancerous change in a benign polyp) that are again associated with mutation and inflammatory bowel disease (malignant change in chronically inflamed lining of the large intestine). Polyposis syndromes are due to genetic mutations which are inherited or sporadic. Hence multiple family members of various generations are seen affected. Continuous inflammation in IBD / UC leads to cellular changes / overgrowth and finally cancer. Colorectal cancer can be due to genetic changes that lead to cancer in multiple organs like large intestine, uterus. Breast, stomach, pancreas etcetera (Lynch syndrome) and is a familial occurrence / hereditary. Important to note that all genetic changes are not inherited, actually majority are de novo (in that patient). Hence majority of the colorectal cancers are sporadic / isolated in occurrence. Few are part of polyposis syndromes, Lynch syndrome or following inflammation.
High fat diet, diet rich in red meat, excess alcohol, diabetes, smoking, obesity / high BMI, inflammation are few associations.
Common symptoms are fresh blood in stools, abdominal pain, bloating, weight loss, constipation, diarrhea (spurious). However patient may be completely asymptomatic and the disease will be detected as an incidental pick up during health check-up. It may be detected during work up for anemia or can manifest as acute intestinal obstruction. It is also detected while screening patients with known backgrounds for high risk of colon cancer like ulcerative colitis, familial polyposis syndromes (e.g. FAP), hereditary conditions predisposing to multiple cancers like Lynch syndrome.
Patients with polyposis syndrome & Lynch syndrome can develop cancers at younger age ; in their thirties and forties. Family members of these patients may also have this problem or are at high risk to develop cancer. Patients with inherited polyposis syndrome have involvement of other organ systems too, depending on genes involved. This includes brain tumors, thyroid cancer, gastric / duodenal polyps, liver tumors etcetera. Occasionally patients without known family history can also have these mutations (sporadic mutation) and may or may not pass it to the next generation.
Gastrointestinal & Hepatopancreatobiliary Surgeon