Colon Cancer or Bowl Cancer - Colorectal polyps, types, symptoms, causes, cure and treatment.

What is Colorecatal polyps or colon cancer?

A colorectal polyp is a small clump of epithelial cells that form a small bump or overgrowth of tissue along the lining of the colon or rectum. The cells lining the colon and rectum are constantly dividing, and typically when there’s an overgrowth of tissue it’s benign, but some can become malignant, meaning that the dividing cells can start invading nearby tissues over time.

Types of Colorectal polyps

There are various types of colorectal polyps. The most common ones are adenomatous polyps,also called colonic adenomas. They form when there is a mutation in the adenomatous polypos is coli gene or APC gene, which is a tumor suppressor gene that regulates cell grow.

When the APC gene is mutated, the epithelial cells start to quickly divide forming polyps. But even though they are dividing, these polyps only become malignant - meaning they only invade nearby tissues if there are additional mutations in other tumor suppressor genes like the p53 gene or in proto-oncogenes like K-Ras. Some people with a genetic condition called familial adenomatous polypos is syndrome or FAP are born with a mutation in their APC gene, and they end up developing hundreds or even thousands of polyps in their colon. These people often need to have their entire colon surgically removed because having so many polyps increases the chance that one cell among all of those polyps will develop another mutation and become malignant.

Adenomatous polyps can also be classified histologically based on their growth pattern as being tubular where the growth has little holes within it looking at a cross section of tissue or a tube if you imagine it in three dimensions or villous where the growth looks like a little tree with branches. Some adenomatous polyps look like a mix of the two with tubes and tree-like structures and are called tubulovillous. 

This description is helpful because it turns out that a growth with a more villous growth pattern is more likely to become malignant,and therefore needs more frequent monitoring if it isn’t surgically removed. 

Another classification is based on whether the adenomatous polyp is pedunculated which means that it is attached to the colon wall by a stalk and is therefore able to freely swing around, or sessile, which means that it’s firmly attached to the colon wall. It turns out that the sessile adenomatous polyps are more likely to become malignant.

Serrated polyps are a second type of polyp,and they get their name because the cells have a characteristic ‘saw tooth’ appearance under a microscope. Within the DNA of the cells in these polyps there are specific stretches of nucleotides that are called CpG islands. CpG islands are found in most promoter regions of genes which are the DNA sequences responsible for the initiation of gene transcription. In the cells that make up serrated polyps,the nucleotides that make up the CpG islands have methyl groups added to them and this silences the promoters, which in turn silences the genes that the promoters help to get transcribed. Unfortunately, this includes DNA repair genes,so by having them silenced, errors during DNA replication don’t get fixed. This can lead to a variety of mutations including ones that cause cells to rapidly divide and potentially become malignant as well. It turns out that small serrated polyps are also known as hyper plastic polyps, and are rarely malignant, whereas larger serrated polyps which are typically flat and sessile, have a greater tendency to become malignant. Another type of polyps are inflammatory polyps,which often follow a bout of ulcerative colitis or Crohn's disease and do not become malignant.

A final group are hamartomatous polyps which are normally made up of a mixture of tissues and have a distorted architecture. Hamartomatous polyps are often associated with genetic syndromes like juvenile polypos is and Peutz-Jegher’s syndrome. Risk factors for developing polyps, include anything that pre disposes towards a genetic mutation, which is likely to happen if there are more cell divisions.

Causes

This includes genetic conditions, as well as anything that injures the bowel wall, like cigarette smoke, inflammatory bowel  disease and old age itself.

Symptoms

Most of the time, polyps don’t cause symptoms and are spotted on a colonoscopy, which is when a camera looks directly at the colon and rectum. However, in some cases, a polyp can ulcerate causing rectal bleeding, and sometimes that bleeding can be very subtle and go unnoticed,but can result in anemia over time. Rarely, if a polyp is very large, it can cause obstructive symptoms like abdominal pain and constipation.

Diagnosis

A diagnosis of the type of polyp is done by biopsy, and treatment usually involves using a wire l

op to cut out the polyp followed by cauterisation to prevent bleeding,

a procedure called polypectomy – which literally means polyp removal. Part of the bowel may also need to be surgically removed if the polyp is particularly large, or if there are many polyps in that section of bowel.

Fortunately, there’s evidence that a healthy diet with lots of green vegetables, legumes, and fruits can help prevent polyps from forming in the first place - yet one more reason to eat what your mother serves you.

Alright, as a quick recap,

there are  different types of polyps and the ones that have the potential to become malignant are the adenomatous polyps and serrated polyps. Typically polyps are found on colonoscopy and can be removed using a polypectomy.