Cancer Information

Colon and Rectum Cancer: Comprehensive Overview

Overview

Colorectal cancer (CRC) arises from abnormal growth of cells in the colon or rectum, often beginning as benign polyps that transform into malignant tumors over time. It is the third most common cancer worldwide and a leading cause of cancer-related deaths. Subtypes include adenocarcinoma (most common), mucinous carcinoma, and signet-ring cell carcinoma.

Colorectal cancer (CRC) arises from abnormal growth of cells in the colon or rectum, often beginning as benign polyps that transform into malignant tumors over time. It is the third most common cancer worldwide and a leading cause of cancer-related deaths. Subtypes include adenocarcinoma (most common), mucinous carcinoma, and signet-ring cell carcinoma.

Causes & Risk Factors

Known Causes

Colorectal cancer develops due to genetic mutations and environmental factors. Common causes include: - Accumulation of mutations in oncogenes and tumor suppressor genes (APC, KRAS, TP53, mismatch repair genes) - Chronic inflammation (ulcerative colitis, Crohn’s disease) - Dietary and lifestyle factors (high red/processed meat, low fiber, obesity, alcohol)

Risk Factors

- Age over 50 years
- Family history of colorectal cancer or adenomatous polyps
- Inherited syndromes (Lynch syndrome, Familial Adenomatous Polyposis)
- Personal history of inflammatory bowel disease (Crohn’s, ulcerative colitis)
- High intake of red or processed meat
- Low fiber diet, low physical activity
- Obesity and metabolic syndrome
- Smoking and alcohol consumption
- Type 2 diabetes
- Prior abdominal or pelvic radiation

Symptoms & Early Signs

Early Warning Signs

- Rectal bleeding or blood in stool - Change in bowel habits (diarrhea, constipation, narrowing of stool) - Persistent abdominal discomfort (pain, cramps, bloating) - Unexplained weight loss - Fatigue or weakness - Iron-deficiency anemia (especially in older adults)

Common Symptoms

- Blood in stool (bright red or dark tarry stools)
- Change in bowel habits lasting >4 weeks
- Abdominal pain or cramping
- Unexplained weight loss
- Weakness and fatigue
- Tenesmus (feeling of incomplete evacuation)
- Bowel obstruction in advanced cases
- Metastatic symptoms: liver pain, jaundice, cough, bone pain

Diagnosis

- Screening colonoscopy (gold standard) - Sigmoidoscopy (for rectal and sigmoid evaluation) - Fecal occult blood test (FOBT) or fecal immunochemical test (FIT) - CT colonography (virtual colonoscopy) - Biopsy during endoscopy (histopathological confirmation) - Imaging: CT, MRI, PET scans (for staging) - Blood tests: CEA (Carcinoembryonic antigen), CBC (to check anemia) - Molecular testing: MSI, KRAS, NRAS, BRAF mutations

Staging Information

TNM staging system: - Stage 0: Carcinoma in situ (confined to mucosa) - Stage I: Tumor limited to submucosa or muscularis propria - Stage II: Tumor extends through muscularis, no nodal involvement - Stage III: Regional lymph node involvement - Stage IV: Distant metastasis (liver, lung, peritoneum, bone)

Treatment Information

Treatment Overview

- Surgery: Colectomy, proctectomy, total mesorectal excision - Radiotherapy: Often for rectal cancer (pre- or post-operative) - Chemotherapy: 5-FU, capecitabine, oxaliplatin, irinotecan - Targeted therapy: Bevacizumab, cetuximab, panitumumab (based on RAS/RAF status) - Immunotherapy: Checkpoint inhibitors (pembrolizumab, nivolumab) in MSI-high/dMMR cancers - Palliative/supportive care for advanced cases

5-Year Survival Rate

N/A

Available Treatments

0

Treatment Options

Prognosis & Outlook

- Prognosis depends on stage, molecular subtype, and response to therapy - 5-year relative survival rates: - Stage I: ~90% - Stage II: ~70–85% - Stage III: ~50–70% - Stage IV: ~15%

Prevention & Early Detection

- Regular screening (colonoscopy, FIT, sigmoidoscopy) starting at age 45–50 - Maintain healthy weight and active lifestyle - High-fiber, low-fat diet with fruits and vegetables - Limit red and processed meat consumption - Avoid smoking and excessive alcohol - Aspirin/NSAIDs may reduce risk in high-risk individuals (under medical advice) - Genetic counseling/testing for high-risk families

Support & Resources

- Healthcare team: Oncologists, gastroenterologists, surgeons, oncology nurses - Patient support groups (hospital-based, community programs) - Global: Colorectal Cancer Alliance, Fight Colorectal Cancer, American Cancer Society - Online communities: CancerCare, Colon Cancer Coalition forums - Counseling & mental health services - Nutritional and rehabilitation support

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Quick Facts

Cancer Type Colon and Rectum Cancer: Comprehensive Overview
Incidence Rate - Global incidence: ~1.9 million new cases annual
Mortality Rate - Global mortality: ~930,000 deaths annually - Sec
Survival Rate N/A
Treatment Options 0
Age Groups - Most cases occur in people over 50 years old - Increasing incidence in younger adults (<50 years), especially in developed countries
Gender - Affects both men and women almost equally - Slightly more common in men worldwide

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