Introduction  

What is adenoma? 

Adenoma is a benign tumour of tissues that releases substances, known as glandular tissue. It most commonly occurs in the colon, which contains glandular tissue that produces mucus to nourish the gut microbiome whilst protecting the intestinal lining from pathogens.^1,2

An adenoma is an abnormal clump of cells that typically occurs in the colon. (Photo Credit: BioRender.com) 

Adenomas can be classified into three main types based on their growth patterns, which include:^1,3

• Tubular - characterised by tube-like gland structures 
• Villous - consists of finger-like projections 
• Tubulovillous - a mixture of both tubular and villous features

Tubular adenoma has been reported as the most common type of adenoma, compared to villous and tubulovillous adenomas. This statistic is based on data from individuals aged 60-74 who participated in the English Bowel Cancer Screening Programme between April 2006 and March 2020.¹

Why does diagnosis matter?

Tumours are small clumps of cells that occur when cells lose control of cell growth and division. They can be categorised as either benign (non-cancerous) or malignant (cancerous). Benign tumours tend to grow slowly and are less likely to spread to other parts of the body, whereas malignant tumours can invade and destroy surrounding tissues. Since benign tumours do not cause harm to surrounding tissues, they are generally less life-threatening and may not present symptoms.⁴

However, depending on their size and location, they can result in symptoms and, in some cases, pose serious health risks by pressing on vital organs and impairing their function. In the cases of tubular adenoma, the risk they can pose is disrupting bowel movement, which can result in pain or bleeding.^1,5

Additionally, tubular adenomas are typically considered to be precancerous, which is identified during the diagnostic process. Once the polyps are removed, a follow-up screening is necessary to prevent the development of colon cancer.^1,6 

It is, therefore, crucial to diagnose adenomas early to reduce the risk of these serious health complications. In this article, we will be exploring: 

• How tubular adenomas are first detected
• Diagnosis via colonoscopy-guided biopsy and histopathological tests
• Challenges and considerations

How tubular adenomas are first detected?

Symptoms 

Doctors typically recognise health problems through the symptoms that the patient presents. If they suspect an issue, they will arrange further tests to confirm their diagnosis. Tubular adenoma can cause various symptoms by affecting bowel movement, including:¹

• Diarrhoea
• Constipation
• Weight loss
• Loss of appetite
• Abdominal pain
• Bowel obstruction
• Rectal bleeding
• Iron deficiency due to bleeding

Screening programmes

The UK has established several screening programs to detect cancer early, even before symptoms appear. Currently, the English Bowel Cancer Screening Programme is available for individuals aged 50-74. Its goal is to detect early signs of bowel cancer and identify those who may need a colonoscopy for further examination.⁶ 

What to expect from the English Bowel Cancer Screening Programme? 

The Faecal Immunochemical Testing (FIT) kits are non-invasive tests that are designed for easy use at home. Simply follow the provided instructions carefully to collect a stool sample and ensure it is correctly dated. Once completed, place the sample in the return envelope provided with the kit and send it back by post. 

How does the FIT kit work? 

FIT kits are sensitive to products resulting from the breakdown of haemoglobin in the blood, which is typically not present in the faeces. This makes them an effective indicator of abnormalities in the colon.⁷

How are FIT kits useful for tubular adenoma detection? 

Although only a small proportion of tubular adenomas cause bleeding, FIT kits are still effective in detecting these cases. Once detected, a colonoscopy will be scheduled to confirm the diagnosis and remove the polyps. Pathologists will then perform a histopathological examination of the biopsy to identify any precancerous adenomas, significantly reducing the risk of cancer.⁸

Diagnosis: a colonoscopy-guided biopsy 

What is a colonoscopy? 

A colonoscopy is a procedure that enables both diagnosis and treatment. It involves examining the colon using a high-definition camera mounted on the tip of a flexible, tube-like device called a colonoscope. The camera allows doctors to visualise any abnormal growths in the colon. Alongside the camera, the colonoscope is equipped with tools to clean the lens, remove polyps, and collect biopsy samples for further analysis.⁹

A colonoscope is inserted into the colon through the rectum for examination. (Photo Credit: BioRender.com)

What are the different biopsy techniques? 

There are two types of tools required for the removal of polyps, which are called cold forceps and snares.¹⁰

Different tools are used to take biopsies from the colon, including cold forceps and snare. (Photo Credit: BioRender.com)

Cold forceps 

Typically used for polyps ranging from 1-3 mm in size, this tool functions like pliers and is designed to grasp and remove the polyp.¹¹

Cold snare

Commonly used to remove polyps 1 cm or larger, this tool consists of a metal ring that can be opened around the polyp and then closed to cut it off.¹¹

Diagnosis: histopathological examination of tubular adenomas  

What is a histopathological report? 

It is a crucial diagnostic process that is performed by pathologists, who use their expertise to identify cellular abnormalities under a microscope. It requires an in-depth understanding of how both healthy and diseased tissues appear. The biopsy is first processed, embedded in paraffin wax, and then carefully sliced and stained so that it can be visualised under a microscope.¹²

What are the histopathological features of tubular adenoma?

Pathologists can determine the severity of the polyps based on their size and how disordered they look under a microscope¹³

They assess the following features:¹³

• Increased number of glands
• Enlarged epithelium
• Darker staining of the nuclei
• Single layer of cells that appear as though they are in multiple layers
• Cells that have reverted to an immature state

Since the molecular changes from adenoma to cancer are well-established, blood tests can also be performed to detect genetic mutations, such as KRAS, which indicate an increased risk of colorectal cancer.¹

Challenges and considerations 

FIT kits are highly valuable for identifying patients who require a colonoscopy. Without them, colonoscopy would not be an effective primary screening method, as it is costly and impractical. Also, participation rates would likely decline due to the invasive nature of the procedure.⁹ 

Considerations of FIT kit 

FIT tests are highly accurate for detecting blood in the stool, which is a potential sign of colorectal cancer. Despite their effectiveness, they are less sensitive for detecting early-stage or small polyps, which may not yet be bleeding.^7,14

Challenges of colonoscopy 

A drawback of colonoscopies is the potential for risks, including rectal tears, bleeding, pain and bloating. Furthermore, using cold forceps to remove polyps can be challenging, as it may cause bleeding that reduces visibility and can result in incomplete polyp removal.^9,11

FAQs

How to reduce the risk of tubular adenoma?

Reduce smoking, alcohol consumption, and fat intake while increasing physical activity.¹

What foods to avoid if you have colon polyps? 

Avoid red meat and processed meat.¹⁵ 

Can tubular adenomas recur? 

The risk of tubular adenoma recurrence is generally low but increases if the adenoma is large or the patient is over the age of 50. Follow-ups may be recommended in these cases.¹⁶ 

Can anyone get a colonoscopy? 

No, your doctor will need to assess whether a colonoscopy is necessary and refer you to a specialist. However, if the result from your FIT kit is positive, you will be automatically referred for a colonoscopy.

How long does it take to recover from a colonoscopy? 

Recovery is typically short, but the effects of sedation can linger. You should avoid returning to normal activities for at least 24 hours. This includes, but is not limited to, cooking, driving, and operating machinery. 

Summary  

Tubular adenoma is a benign tumour that is typically not life-threatening, though its size and location can make it potentially dangerous. Diagnosis is essential, as tubular adenomas can severely affect bowel movements or be precancerous. Colonoscopy is a valuable tool for both detecting and removing polyps, allowing for biopsy collection. Pathologists analyse biopsy samples using histopathological techniques to determine the presence of precancerous adenomas. Early detection of tubular adenoma is crucial, as it can significantly reduce the risk of cancer development.