What Cancers Cause Rectal Bleeding?

Is Rectal Bleeding a Cancer Symptom? Types, Causes & What to Do

Digestive health plays a crucial role in our overall well-being. Our gastrointestinal tract is responsible for digestion, eliminating waste, and maintaining the body's essential functions. However, when something goes wrong, like rectal bleeding, it often causes alarm.

Rectal bleeding refers to the passage of blood from the rectum, which may appear as bright red, dark red, or even black stools. While it is often linked to benign conditions such as haemorrhoids or anal fissures, persistent or unexplained bleeding can be a warning sign of something more serious, like cancer.

Knowing which cancers can cause rectal bleeding, what symptoms to watch for, and how to respond effectively is crucial. Early detection often leads to better treatment outcomes. Continue reading to find out what cancer can cause rectal bleeding.

What Types of Cancer Can Cause Rectal Bleeding?

Rectal bleeding can be a warning symptom for several types of cancers. Listed below are the most common ones:

1.  Colorectal Cancer

This is the most common malignancy associated with rectal bleeding. Colorectal cancer originates in the colon or rectum, often from precancerous polyps.

Symptoms:

• Bright red blood in the stool or on toilet paper
• Changes in bowel habits (diarrhoea, constipation)
• Abdominal pain or cramping
• Unexplained weight loss
• Fatigue

Note: Bleeding may be intermittent or mistaken for haemorrhoids, delaying diagnosis.

2.  Anal Cancer

Though less common, anal cancer can also cause bleeding. It develops in the tissues at the end of the rectum.

Symptoms:

• Rectal bleeding
• Anal pain or pressure
• A lump or mass near the anus
• Itching or discharge

Anal cancers are often linked to the human papillomavirus (HPV).

3.  Gastric (Stomach) and Small Intestine Cancer

Advanced gastric or small bowel cancers may cause melena, but early-stage tumors often present with occult bleeding or anemia. Upper GI (gastrointestinal) cancers can lead to gastrointestinal bleeding, which results in dark or black stool (melena) due to partially digested blood.

Symptoms:

• Tarry or black stools
• Nausea or vomiting
• Bloating or indigestion
• Weakness and fatigue

Bleeding may not be immediately visible but shows up through signs of anaemia.

4.  Oesophageal Cancer

This cancer can cause upper GI bleeding that, over time, results in dark stool or occult blood detected in laboratory tests.

Symptoms:

• Difficulty swallowing
• Unintentional weight loss
• Chest pain
• Black stools (advanced cases)

5.  Leukaemia

Leukaemia is a cancer of the blood and bone marrow, not the digestive tract, but it can rarely cause rectal bleeding due to decreased platelets and clotting issues.

Symptoms:

• Easy bruising and frequent nosebleeds
• Bleeding gums
• Fatigue
• Fever and frequent infections
• Rectal bleeding due to fragile blood vessels

How to Prevent Rectal Bleeding from Cancer?

While not all cancers are preventable, certain habits can significantly lower your risk, such as:

1.  Maintaining Routine Screenings

• Get regular colonoscopies, especially after age 45 or earlier if there is a family history of colorectal cancer.
• Screenings like Faecal Occult Blood Tests (FOBT) can help detect early signs of hidden bleeding.

2.  Balancing a Healthy Diet

• Eat a high-fibre diet rich in fruits, vegetables, and whole grains.
• Limit consumption of red and processed meat.
• Stay hydrated.

3.  Regular Exercise

• Physical activity supports bowel movement and overall digestive health.
• Aim for at least 30 minutes a day, five times a week.

4.  Avoid Smoking and Limit Alcohol Intake

• Both smoking and alcohol consumption are risk factors for GI cancers.
• Quitting smoking and moderating alcohol intake can significantly reduce cancer risk.

5.  Vaccinated for HPV

• HPV vaccines can prevent most cases of anal and cervical cancers.

What are the treatment options for cancers causing rectal bleeding?

If cancer is confirmed as the cause of rectal bleeding, treatment will vary based on the type and stage of cancer:

1.  For Colorectal Cancer (Colon or Rectal Cancer)

• Surgery: Often the first step if the tumour is resectable. Procedures like colectomy or low anterior resection aim to remove the cancerous portion of the intestine.
• Radiation Therapy: Commonly used in rectal cancer, especially before surgery, to shrink the tumour and reduce bleeding.
• Chemotherapy: Used before or after surgery to eliminate cancer cells and prevent recurrence. It may also be used in advanced cases to relieve symptoms.
• Targeted Therapy and Immunotherapy: Recommended for specific genetic profiles or metastatic disease.

2.  For Anal Cancer

• Chemoradiation: The standard treatment combines chemotherapy and radiation. It often helps avoid surgery while preserving normal bowel function.
• Surgery: It may be required if the tumour does not respond to initial treatment or recurs later.
• Supportive Care: Includes managing symptoms like bleeding, pain, and infections during treatment.

3.  For Advanced or Metastatic Cancers

• Palliative Care: Aims to control rectal bleeding, pain, and other symptoms to improve comfort and quality of life.
• Endoscopic Procedures or Embolisation: It may be used to stop bleeding in cases where surgery is unsuitable.
• Stenting: In some cases, a stent may be placed to relieve obstruction and reduce bleeding.

4.  Other General Supportive Measures

• Iron Supplements or Transfusions: To treat anaemia caused by chronic blood loss.
• Dietary Support: Nutritional planning is essential to maintain strength during treatment.
• Psychological Support: Cancer diagnosis and rectal symptoms can be emotionally challenging—counselling is highly beneficial.

When to See a Doctor for Rectal Bleeding Due to Cancer?

You should seek medical attention if:

• Rectal bleeding persists for more than a few days.
• You experience unexplained weight loss or fatigue.
• There are noticeable changes in bowel habits.
• You feel abdominal or rectal pain.

A doctor typically begins with a physical exam and medical history and recommends diagnostic tests, such as a colonoscopy, blood tests, or imaging scans, to determine the cause.

Rectal bleeding can be caused by either conditions like haemorrhoids or more severe ones, such as cancer. Among the cancers that may present this symptom are colorectal, anal, gastric, oesophageal, and leukaemia. Recognising the warning signs, undergoing timely screenings, and adopting a healthy lifestyle can make a significant difference in managing cancer.

At Star Health, we offer extensive coverage for cancer-related conditions and treatments under our Star Cancer Care Platinum Insurance policy, tailored to your specific needs. We also provide hassle-free claim settlements with reduced turnaround time across over 14,000 network hospitals in India.