In a previous post we discussed signs of colon cancer an how they sometimes mimic hemorrhoids symptoms. Today we are going to get in a little deeper with some discussion about colon polyps.
First things first, What’s polyp? A polyp is a grossly visible mass of cells that protrudes from the inner layer to outer layer of the Colon (Large intestine). There are two types of Polyps of the colon.
First, the Non neoplastic or Non adenomatous, in other words, Non cancerous.
And Neoplastic or Adenomatous Polyps, in other words, Cancerous.
Non cancerous Polyps are the ones that account for 90% of detected cases of Colon polyps. In which, 50% of people are over the age of 60.
The Non cancerous polyps are further divided into four types;
1) Hyperplastic Polyps – This type is the most commonly appearing non cancerous polyp. The cause – Abnormal maturation of cells that lines our Large intestine. and why is that? though there are no clear explanations, doctors believe that it may be due to our sedentary life style, the chemicals we are using. These Polyps are small in diameter and predominantly found in distal sigmoid colon and rectum (Last parts of your large intestine)
2) Inflammatory Polyps – Mostly it appears if the person is having Chronic Ulcerative Colitis, which causes Inflammation and Ulcer. Inflammatory Polyp are composed of regions of Inflamed Mucosa surrounded by ulcers. It is highly associated with the risk of developing cancer.
3) Lymphoid Polyps – are regions of mucosa that contain exaggerated intramucosal lymphoid tissue. In simple words, the polyp contains lymph tissues within them.
4) Juvenile Polyps – they develop in the rectum of the children under 5 years of age. It is termed as ‘Hamartomatous’ because, the polyps resembles tumors but it is not. It is tumor like because of the abnormal development of one of the four layers of large intestine called ‘Lamina Propria’. No treatment is required unless they cause obstruction or bleeding.
Cancerous Polyps – They are Malignant as we can see from their name and they differ in their sizes. Usually, smaller lesions are Pedunculated and larger lesions are Sessile ( not free moving).
It is relatively common in elderly population. Men are more liable. It is genetic in condition. For example, individuals with a positive first-degree family history are at a four-fold greater risk of developing Cancerous Polyps.
Convincing evidence that Cancerous polyps are the precursor lesion to colorectal adenocarcinoma comes from persons with the hereditary polyposis syndromes and from animal studies in which adenomas are induced by either carcinogens or genetic manipulation.
Correlative evidence includes the observations that the epidemiology is similar for adenomas and carcinomas, that both lesions are more common in the same anatomic locations, and that adenomatous tissue can often be found in small adenocarcinomas.
Intervention studies have shown that removal of adenomatous polyps leads to a significant decrease in risk for colorectal cancer. (I referred this from a medical book, so, its not my own) Like non cancerous these adenomas are further classified into different types.
There are three of them,
1) Tubular adenomas – the most common type. Accounts for 70% – 85% of all adenomas removed at colonoscopy. They are often Smaller in size and Pedunculated. They contains tubular structures which divides the mucosal surface.
2) Villous adenomas – the rarest among others. Accounts for less than 5% of all adenomas. They are often larger and sessile. They are composed of strands of epithelial cells, finger like (hence the name, Villous) and they project into the lumen of the intestine.
3) Tubulovillous adenomas – Mixture of tubular and villous adenomas. It accounts for 10% – 25% of all adenomas. Its sizes differ considerable from small to large. Small tubular adenomas generally have low malignant potential whereas large villous has high malignant potential, almost 40% of the larger adenomas develop into cancer. and why is that 40% are turning into cancer?
Well, there are two most important factors that decide this, size of the polyp and grade of Dysplasia. For Polyps less than 1 cm in size, the risk for carcinoma is 1 – 3%. Polyps between 1 cm and 2 cm has the risk of 10%. Polyps that are more than 2 cms (those 40% larger polyps are more than 2 cms) has the risk of 40% to become an invasive lesion and cancerous.
Dysplasia ( Abnormal growth or development of cells) is categorized as low or high grade dysplasia. For instance, high grade dysplasia is associated with 27% rate of eventual transformation into cancer. Most patients with Adenomatous Polyps are asymptomatic, means they don’t experience any symptom. But may present with Hematochezia (Passage of bloody stools).
How can we diagnose?
Though we can diagnose it through endoscopy or barium radiography, Colonoscopy is the most accurate tool for diagnosing because of the path the camera goes. In endoscopy, the camera goes through mouth, so large intestine is difficult to see.
But in Colonoscopy, the camera goes through the anus, which is much easier to view the large intestine in detail. However, colonoscopy may not be adequately performed in patients who have advanced diverticulosis or who have had previous pelvic surgery.
In these instances, a combination of double-contrast barium radiography and flexible sigmoidoscopy may be an acceptable alternative. Although fiberoptic colonoscopy remains the “gold standard” for polyp detection, CT colonography may emerge as a viable screening tool for certain sub-sets of patients in the detection of adenomatous polyps and colorectal cancer.
How can we treat it?
Removal of the lesion is best and almost only way. It is achieved during endoscopy by electrocautery. The surgical method is used as an alternative in cases where the endoscopy is not possible. Patients who have undergone resection of an adenomatous polyp are at increased risk for subsequent development of adenomas and colorectal adenocarcinoma.
In general, a follow-up colonoscopy is recommended in 3 years. Earlier colonoscopies may be warranted in patients who have multiple or large sessile adenomas removed.
In contrast, the risk of malignancy is not significantly increased in patients who have had less than three small (<1 cm) tubular adenomas removed; for these individuals, the first follow-up colonoscopy can be delayed to 5 years. If the first follow-up colonoscopy is negative, the second scheduled follow-up can usually be delayed until 5 years. Because it is asymptomatic, the timely diagnosis is the only golden way to minimize the effect.