Overview

What is inflammatory bowel disease?

Inflammatory bowel disease (IBD) is an umbrella term that refers to the chronic inflammation of the gastrointestinal tract (GIT) and is different from irritable bowel syndrome (IBS), which is a chronic disorder of the intestines.^1,2 The GIT extends from the mouth to the anus and is covered in mucosa (tissue that contains or creates a fluid that protects the body, also known as mucous). GIT is essential to life as it is responsible for:³

• Digestion
• Absorbing nutrients 
• Absorbing water
• Eliminating waste products

IBD mainly includes two diseases, Crohn’s disease (CD) and ulcerative colitis (UC).^1,3 The difference between these two conditions largely relates to the fact that UC only affects the colon and rectum, while CD can affect any part of the gastrointestinal tract.^4,5 However, the two conditions share many symptoms including:⁶

• Fatigue
• Bowel frequency
• Abdominal pain

However, the following are more common in Ulcerative colitis than Crohn’s disease cases:⁶

• Blood with bowel movement
• Urgent bowel movement
• Mucus with bowel movement

What are tubular adenomas?

Tubular adenomas refers to abnormal but non-cancerous polyps composed of tube-like glandular tissue, most commonly found in the breast or colon.^7,8,9,10 Although they do not seem to increase the risk of breast cancer, in the colon, they are often a sign of upcoming colon cancer.^8,9,10 Indeed, around 95% of colon cancers develop from tubular adenoma.¹⁰ For the rest of this article, we focus on colonic tubular adenomas. 

Tubular adenomas are the most common, least villous and least likely to be cancerous type of adenomas found in the colon, with a prevalence of over 80% of adenoma cases.¹¹ They do not cause pain or other symptoms and are identified by colonoscopy.¹² In some cases, they can cause abdominal discomfort, changes in bowel movement frequency and bleeding of the rectum.¹² 

The prevalence of tubular adenomas varies dramatically depending on populations; there is therefore no accepted incidence rate for the condition. The formation of tubular adenoma is mostly related to genetic factors, including:¹²

• Genetic predisposition: The genetic disorder Familial adenomatous polyposis causes the development of multiple polyps, usually exceeding a hundred. It is found in 1 in 8000 to 1 in 14000 people. However, it only accounts for around 1% of colon cancers^12,13
• Genetic mutations: mutations of the tumour suppressor gene (adenomatous polyposis coli) causing its inactivation and the formation of adenomas¹⁴ 

In addition to genetic risks, other factors could increase the risk of tubular adenomas formation, such as:

• Being male¹⁵
• Increasing age¹⁵
• Consumption of fat foods and alcohol¹²
• Tobacco smoking¹²
• Comorbidities including acromegaly, Streptococcus bovis, IBD¹²

Tubular adenomas in IBD

Tubular adenomas are not always present in IBD cases, and people without IBD can also get them. However, having IBD increases the risk of having colorectal cancer by 18% (after 30 years of disease), meaning that patients with IBD are monitored closely so that the identification of pre-cancerous polyps is not missed.¹⁶

Prevalence and risks

It is impossible to determine the exact prevalence rates of tubular adenomas in patients with IBD. However, a study found that between a group of patients with IBD and another group of non-IBD patients, the prevalence of tubular adenomas was lower for those with IBD.^17,18 This can be because of a range of factors, including that people with IBD are monitored from a young age and are less likely to have tubular adenomas than the other group or that IBD treatments might prevent the formation of tubular adenomas.¹⁷

Despite this, it should be noted that the chronic inflammation of the colon experienced by people with IBD is likely to contribute to the formation of polyps.¹⁹ 

Diagnosis

Tubular adenomas are asymptomatic (do not cause symptoms), meaning a patient can only be diagnosed if the polyps are visually identified during a visual examination, such as a colonoscopy. In the case of patients without IBD, examination occurs if a faecal immunochemical test is positive, indicating the presence of blood in their stool. In the United Kingdom, people aged between 54 and 74 are invited to take one of these tests every two years as part of the NHS bowel screening programme. 

For patients with diagnosed IBD, the NHS recommends getting colonoscopies every 3 to 5 years (depending on the severity of the condition) for disease monitoring. This allows regular opportunities for tubular adenomas to be found, removed and sampled for biopsy (to determine if the tumour is cancerous).

Prevention and treatment

Despite the formation of tubular adenoma being largely due to genetic factors, reducing the length and frequency of inflammation episodes for people with IBD will decrease the odds of developing polyps.¹⁹ To limit flare-ups, the NHS recommends:

• Medication: to reduce inflammation or to suppress the immune system (in cases of CD)
• Surgery: to remove all or parts of the colon (UC) or the intestine (CD)
• Healthy diet and more frequent, smaller meals (5 or 6 instead of 3)
• Avoid trigger foods (for cases of CD)
• Staying very hydrated
• Reducing stress
• Stop smoking

The only treatment for tubular adenomas is complete removal by polypectomy during colonoscopy. Considering the increased risks for polyps evolving into cancerous tumours for patients with IBD, it is important to follow NHS guidelines and get checked regularly.^16,20

FAQs

Can tubular adenoma be transmitted?

No, tubular adenoma cannot be transmitted from person to person. However, it is possible to inherit the genetic disorder Familial adenomatous polyposis, which, generally, causes the formation of many polyps. Despite the large number of adenomas formed as a result of this condition, it is only responsible for around 1% of colon cancers.^12,13

Is it possible to prevent tubular adenoma from developing?

Yes and no. It is possible to reduce the environmental risk factors for tubular adenomas (for example, fat food, alcohol and smoking), but the condition is largely caused by genetic mutations and can therefore not be avoided.

Should I get checked for tubular adenoma if I have IBD? 

If you have IBD, the treatment plan established with your gastroenterologist, following NHS guidelines, should include regular colonoscopies (every 3 to 5 years) to monitor your condition. During the colonoscopies, specialists check for any polyps and remove them if present.

Summary

Tubular adenomas are non-cancerous polyps found in the colon. They can evolve into cancerous tumours and, as a result, are considered signs of upcoming colorectal cancer. Although patients with IBD are less at risk of forming tubular adenomas, when they do, they often evolve into cancer. Tubular adenomas do not cause symptoms. Therefore, their presence needs to be identified visually during examinations. Thankfully, the IBD management guidelines advised by the NHS involve frequent colonoscopies, where tubular adenomas can be identified and removed, limiting the risk of colorectal cancer developing.