Bowel Cancer: Symptoms, Diagnosis & Treatment

What is Bowel Cancer?

Bowel cancer, also known as colorectal cancer, is a malignant growth that develops in the colon or rectum. Most colorectal cancers are adenocarcinomas that evolve from polyps, which may be present for ten years or more before malignancy develops. Colorectal cancer is locally invasive, though metastatic spread may occur before local growth produces noticeable symptoms. The most common site for metastatic spread is the liver, with other sites such as the lungs, brain, and bone being unusual in the absence of liver involvement.

The development of bowel cancer typically follows a predictable progression. An adenoma initially forms and then progresses to an advanced adenoma (greater than 1cm in size and/or with villous histology) before finally becoming colorectal cancer. This process is driven by the accumulation of mutations and epigenetic alterations and takes 10–15 years to occur, though it can progress more rapidly in certain settings such as Lynch syndrome.

Where are the Colon and Rectum?

The colon and rectum form the lower portion of the digestive system. The colon is the large intestine, approximately 5-6 feet long, which absorbs water and electrolytes from food waste. The rectum is the final section of the large intestine, about 5-6 inches long, which stores stool until it is passed from the body. Bowel cancer can develop in either the colon (colon cancer) or the rectum (rectal cancer), and together these cancers are referred to as colorectal cancer.

What Causes Bowel Cancer?

Several risk factors contribute to the development of bowel cancer. These include:

• Age: Bowel cancer mostly occurs in people aged over 50
• Inflammatory Bowel Disease (IBD): Chronic colitis due to inflammatory bowel disease is associated with increased risk of colorectal cancer, with risk increasing with longer duration of IBD. Those with inflammatory bowel disease have a 70% increased risk
• Family History: A strong family history of colorectal cancer increases risk
• Previous Adenomatous Polyps: Individuals with previous colorectal adenomatous polyps are at higher risk
• Previous Colorectal Cancer: Patients with previous resection of a colorectal cancer require targeted surveillance
• Genetic Syndromes: Lynch syndrome and familial adenomatous polyposis significantly increase risk and can cause faster progression
• Lifestyle Factors: Diet, physical activity, obesity, smoking, and alcohol consumption may influence risk

Bowel Cancer Symptoms

The most common presenting symptoms and signs of cancer or large polyps are rectal bleeding, persisting change in bowel habit, and anaemia. Patients present with characteristic symptoms including abdominal pain, rectal bleeding, and changes in bowel habits, but diagnosis is often delayed.

Common symptoms include:

• Rectal bleeding or blood in the stool
• Persistent change in bowel habit (diarrhea, constipation, or alternating patterns)
• Abdominal pain or discomfort
• Anaemia (which may cause fatigue and weakness)
• Weight loss
• A sense of incomplete bowel emptying
• Mucus in the stool

It is important to note that early-stage bowel cancer may not produce any symptoms. Additionally, these symptoms can be caused by conditions other than cancer. However, any persistent changes in bowel habits or rectal bleeding should be evaluated by a healthcare professional.

Differential Diagnosis

Various conditions can present with symptoms similar to bowel cancer and must be considered during diagnosis. These include inflammatory bowel disease (Crohn’s disease and ulcerative colitis), irritable bowel syndrome, diverticular disease, haemorrhoids, anal fissures, infectious colitis, and polyps. A thorough medical history, physical examination, and appropriate investigations are necessary to distinguish bowel cancer from these other conditions.

Investigations

Several investigative methods are employed to diagnose bowel cancer and assess its extent:

• Colonoscopy: The gold standard investigation, allowing direct visualization of the entire colon and rectum, with ability to obtain tissue biopsies and remove polyps
• Flexible Sigmoidoscopy: Visualization of the lower colon and rectum only
• Faecal Occult Blood Test (FOBT): Detects hidden blood in the stool
• Complete Blood Count: May reveal anaemia
• Carcinoembryonic Antigen (CEA): A tumour marker that may be elevated in colorectal cancer
• Computed Tomography (CT) Scan: Assesses local extent of disease and distant metastases
• Magnetic Resonance Imaging (MRI): Particularly useful for rectal cancer staging
• Positron Emission Tomography (PET) Scan: Used in selected cases to detect metastases

Staging

Staging determines the extent of cancer spread and guides treatment decisions. The TNM staging system is commonly used:

Stage 1: Cancer confined to the mucosa or submucosa, without lymph node involvement.

Stage 2a: Cancer growth into the outer covering of the bowel wall (T3, N0, M0).

Stage 2b: Cancer growth through the outer covering of the bowel wall and into tissues or organs next to the bowel (T4).

Stage 3: Lymph node involvement. Stage 3a involves cancer growth into the muscle layer, and between 1 and 3 nearby lymph nodes contain cancer cells (T1, N1, M0 or T2, N1, M0).

Stage 4: Distant metastases present, commonly in the liver, lungs, or peritoneum.

In general, the more advanced the cancer (the more it has grown and spread), the less chance that treatment will be curative. However, treatment can often slow the progress of the cancer.

Bowel Cancer Treatment

Surgery remains the definitive treatment for apparently localised colorectal cancer. New treatment options have emerged, providing additional options for patients including laparoscopic surgery for primary disease, more-aggressive resection of metastatic disease (such as liver and pulmonary metastases), radiotherapy for rectal cancer, and neoadjuvant and palliative chemotherapies.

Surgical Treatment

Surgery is the primary treatment modality for localised bowel cancer. The extent of surgery depends on the location and stage of the cancer. Procedures may include hemicolectomy (removal of part of the colon), anterior resection (for left-sided cancers), abdominoperineal resection (for very low rectal cancers), and multivisceral resection (when cancer has invaded adjacent organs). Laparoscopic (minimally invasive) surgical techniques are increasingly used and offer advantages including reduced postoperative pain, shorter hospital stay, and faster recovery.

Chemotherapy

NICE recommends that when offering multiple chemotherapy drugs to patients with advanced and metastatic colorectal cancer, one of the following sequences of chemotherapy should be considered: FOLFOX (folinic acid plus fluorouracil plus oxaliplatin) as first-line treatment, then single agent irinotecan as second-line treatment. Both radiotherapy and chemotherapy can improve survival rates after potentially curative surgery.

Radiotherapy

Radiotherapy for rectal cancer and neoadjuvant and palliative chemotherapy represent important treatment components. Radiotherapy may be used before surgery (neoadjuvant) to shrink the tumour or after surgery (adjuvant) to reduce recurrence risk.

Metastatic Disease Management

Over 50% of patients with colorectal cancer will develop liver metastases, but only a minority of patients present with technically resectable disease. Liver resection, with neoadjuvant and adjuvant chemotherapy, is the optimal treatment for colorectal metastases, with around 40% of those undergoing surgical resection alive five years after their diagnosis. Selective internal radiation therapy (SIRT) for unresectable colorectal metastases in the liver can cause serious complications but these are well recognised and infrequent.

Recent Treatment Advances

In 2022, NICE updated its standards on colorectal cancer treatment to include comprehensive testing and personalized approaches. All adults with a new diagnosis of colorectal cancer should be tested for Lynch syndrome. Adults with metastatic colorectal cancer who would be suitable for systemic anti-cancer treatment should undergo testing for RAS and BRAF V600E mutations. Adults who have undergone potentially curative surgical management of their non-metastatic colorectal cancer should be followed up for 3 years to look for local and distant disease progression.

What is the Outlook?

Prognosis depends on several factors, including the stage at diagnosis, the location of the cancer, and individual patient factors. If bowel cancer is diagnosed at an early stage, there is a good chance of a cure.

Around half of people diagnosed with colorectal cancer survive for at least five years after diagnosis. Specifically, 60% are amenable to radical surgery and 70% of these will be alive at seven years (or will have died from non-tumour-related causes). Survival rates relative to age-matched groups without colorectal cancer are now about 45% at five years after diagnosis, with relative survival rates declining only slightly beyond five years (most of those who live this long are cured).

Colorectal cancer is highly treatable if caught early. Treatment typically depends on the location of the cancer and the stage of diagnosis. Despite advances in surgical and medical therapies, cure rates and long-term survival have changed little in the past several decades, emphasizing the importance of screening programmes for early detection.

Screening for Bowel Cancer

Early diagnosis is essential for effective treatment to provide the greatest chance of survival. Colorectal cancer screening can save your life and learn more about screening methods, who should get screened, and how to prepare.

Screening programmes involve a national screening programme for patients without symptoms and normal population risk, and targeted surveillance programmes for those at special risk (such as inflammatory bowel disease or strong family history). Screening involves identifying moderate-risk and high-risk patients through more targeted screening programmes and protocols which select sectors of the population at particularly high risk of colorectal carcinoma.

Screening methods include:

• Faecal Occult Blood Test (FOBT)
• Flexible Sigmoidoscopy
• Colonoscopy
• CT Colonography
• Capsule Endoscopy

The U.S. Preventive Services Task Force (USPSTF) recommends that clinicians selectively offer screening for colorectal cancer in adults aged 76 to 85 years. The USPSTF recognizes the higher colorectal cancer incidence and mortality in Black adults and strongly encourages clinicians to ensure their Black patients receive recommended colorectal cancer screening, follow-up, and treatment.

Frequently Asked Questions

Q: At what age should colorectal cancer screening begin?

A: Screening is typically recommended to begin at age 50 for average-risk individuals, though earlier screening may be recommended for those with family history or other risk factors.

Q: Can bowel cancer be prevented?

A: While not all cases can be prevented, regular screening, maintaining a healthy diet rich in fiber, regular exercise, avoiding smoking and excessive alcohol, and maintaining a healthy weight can reduce risk.

Q: What is the difference between colon cancer and rectal cancer?

A: Colon cancer develops in the colon (large intestine), while rectal cancer develops in the rectum (the final portion of the large intestine). Treatment approaches may differ, particularly regarding radiotherapy for rectal cancers.

Q: Is colonoscopy painful?

A: Most patients receive sedation during colonoscopy, making the procedure comfortable and painless. Mild cramping or pressure may be felt, but pain is not typical.

Q: Can Lynch syndrome increase bowel cancer risk?

A: Yes, Lynch syndrome significantly increases the risk of colorectal cancer and can cause faster progression. All newly diagnosed colorectal cancer patients should be tested for Lynch syndrome.

Q: What follow-up care is needed after bowel cancer treatment?

A: Adults who have undergone potentially curative surgical management should be followed up for 3 years to look for local and distant disease progression.

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Author

Sneha TeteBeauty & Lifestyle Writer

 

Sneha is a relationships and lifestyle writer with a strong foundation in applied linguistics and certified training in relationship coaching. She brings over five years of writing experience to renewcure,  crafting thoughtful, research-driven content that empowers readers to build healthier relationships, boost emotional well-being, and embrace holistic living.

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