The colon and rectum are parts of the large intestine. Colorectal cancer begins when cells in these tissues grow abnormally and can eventually invade nearby tissue or spread elsewhere.
Blood in or on stool
BIMARIDUR HEALTH ENCYCLOPEDIA
Colorectal Cancer
Colorectal cancer is cancer that begins in the colon or rectum. It often develops from a growth called a polyp, some of which can become cancer over time.
Medical illustration
Diagram of the large intestine showing cecum, ascending colon, transverse colon, descending colon, sigmoid colon and rectum.
ICDC18.9
Affected areaColon, rectum, nearby lymph nodes and, when advanced, organs affected by metastatic spread.
ContagiousnessColorectal cancer is not contagious and cannot be transmitted between people through ordinary contact.
01 • QUICK UNDERSTANDING
What is Colorectal Cancer?
02 • BODY & MECHANISM
What happens in the body?
Medical illustration
Diagram of the large intestine showing cecum, ascending colon, transverse colon, descending colon, sigmoid colon and rectum.
Body structure involved
The colon absorbs water and helps form stool. The rectum stores stool before it leaves the body.
How it starts
Many colorectal cancers develop from polyps or other abnormal growths in the bowel lining. Not every polyp becomes cancer, but some types can progress over time.
What happens inside the body
A colorectal tumor can begin in the lining of the colon or rectum. As it grows it may narrow the bowel, bleed, invade surrounding tissues or spread through lymphatic and blood vessels.
03 • TYPES & CLASSIFICATION
Types and classification
Medical illustration
Visual showing colon cancer versus rectal cancer and the major anatomic sections of the colorectal tract.
Classification may include tumor location, histologic type, molecular features and TNM stage. Molecular testing can help guide treatment in selected advanced cancers.
Colorectal cancer can arise in different parts of the colon or rectum and includes different microscopic and molecular subtypes. Colon and rectal cancers may require different treatment approaches because of their location.
04 • SYMPTOMS
Symptoms and warning signs
Medical illustration
Visual showing blood in stool, bowel habit changes, abdominal discomfort, weight loss and fatigue.
Change in bowel habits
Persistent abdominal discomfort
Unexplained weight loss
Fatigue or weakness
Feeling that the bowel does not empty completely
06 • CAUSES
What can cause this disease?
Medical illustration
Visual showing age, family history, polyps, inflammatory bowel disease, tobacco, alcohol, weight and physical inactivity as risk factors.
There is no single cause. Risk is influenced by age, inherited susceptibility, family history, previous polyps or colorectal cancer, inflammatory bowel disease and lifestyle factors.
07 • RISK FACTORS
Who may have a higher risk?
1
Increasing age
2
Personal history of colorectal polyps or cancer
3
Family history of colorectal cancer
4
Inflammatory bowel disease
5
Inherited syndromes such as Lynch syndrome or familial adenomatous polyposis
6
Overweight or obesity
7
Physical inactivity
8
Tobacco use
9
Alcohol use
08 • DIAGNOSIS
How is Colorectal Cancer diagnosed?
Medical illustration
Screening or symptoms → stool testing/colonoscopy → biopsy → pathology → staging.
Diagnosis may involve medical history, physical examination, stool testing, colonoscopy or other visualization procedures, imaging and biopsy. A biopsy allows tissue to be examined for cancer.
Clinical evaluation
Persistent change in bowel habits
Unexplained rectal bleeding
Unexplained iron-deficiency anemia
Unexplained weight loss
Persistent abdominal symptoms
Laboratory tests
Complete blood count when clinically indicated
Iron studies when blood loss or iron deficiency is suspected
Tumor marker testing such as CEA for selected monitoring situations
Molecular testing when indicated
Imaging and scans
CT scan
MRI for selected rectal cancer evaluation
PET-CT in selected situations
Special or confirmatory tests
Colonoscopy
Flexible sigmoidoscopy
Stool-based screening tests
Biopsy
Pathology and molecular testing
09 • DIFFERENTIAL CONTEXT
Conditions that may look similar
Hemorrhoids
Anal fissure
Inflammatory bowel disease
Irritable bowel syndrome
Gastrointestinal infection
10 • EXTENT / STAGE
Stages or severity
Medical illustration
Visual from stage 0 localized abnormal cells through stage IV distant spread.
Colorectal cancer is commonly staged from stage 0 through stage IV based on how deeply the tumor has invaded, lymph-node involvement and distant spread.
Important:
Staging or grading systems differ between diseases. The information here is educational and should be interpreted by a qualified healthcare professional in the context of the individual case.
11 • TREATMENT
How is Colorectal Cancer treated?
Medical illustration
Treatment map showing surgery, chemotherapy, radiation, targeted therapy and immunotherapy according to location and stage.
Treatment depends on location, stage, molecular features and overall health. Options can include surgery, chemotherapy, radiation therapy, targeted therapy and immunotherapy. Rectal cancer may require combined treatment before or after surgery.
Medicines that may be used
Chemotherapy medicines may be used according to cancer type and stage.
Targeted medicines may be used when specific molecular features are present.
Immunotherapy may be appropriate for selected tumors.
Supportive medicines may be used for treatment-related symptoms.
Medicine safety:
Medicines listed here are for educational information only. Do not start, stop, or change a medicine without professional medical advice.
12 • COMPLICATIONS
Possible complications
Possible complications include bowel obstruction, bleeding, anemia, perforation, infection, malnutrition and metastatic disease. Surgery and systemic treatments can also cause complications.
URGENT SAFETY INFORMATION
When should urgent medical help be considered?
Severe abdominal pain with vomiting or marked abdominal swelling
Heavy gastrointestinal bleeding
Fainting or severe weakness associated with bleeding
Symptoms suggesting bowel obstruction
If symptoms are severe, rapidly worsening, or life-threatening, seek emergency medical care immediately.
13 • OUTLOOK
Prognosis and recovery outlook
Medical illustration
Factors influencing outlook: stage, lymph nodes, distant spread, molecular features, treatment response and overall health.
Outlook depends on stage, tumor biology, location, treatment response and overall health. Survival statistics describe populations and do not determine an individual's outcome.
How to interpret these statistics
Survival statistics describe outcomes in groups of people and cannot predict exactly what will happen to one individual. Prognosis depends on factors such as cancer stage, tumor biology, treatment response, overall health, and follow-up.
14 • EPIDEMIOLOGY
How common is it?
Colorectal cancer is a major cancer worldwide. IARC GLOBOCAN 2022 estimated 70,038 new colorectal cancer cases in India across both sexes.
15 • PREVENTION
Risk reduction and prevention
Screening can detect precancerous polyps so they can be removed before they become cancer. Maintaining healthy activity and weight, avoiding tobacco and limiting alcohol can also reduce risk.
16 • PREPARE FOR YOUR VISIT
Questions you may ask your doctor
1
Where is the tumor located?
2
What is the stage?
3
Are lymph nodes involved?
4
Is molecular testing needed?
5
Will surgery be required?
6
What follow-up testing will be needed?
17 • FAQ
Frequently asked questions
Can a polyp become colorectal cancer?
Can colorectal cancer occur without symptoms?
Does blood in stool always mean colorectal cancer?
Is colorectal cancer treatable?
Important medical information
BimariDur provides educational health information to help people understand diseases, symptoms, tests, and treatment concepts. It does not replace examination, diagnosis, or treatment by a qualified healthcare professional.
Do not delay professional medical care because of information read on BimariDur.