Colorectal Cancer Types and Risk Factors

Types of Tumors

• Benign tumors:
  • Most common: adenomas (polyps)
  • Others: lipomas, leiomyomas, and inflammatory polyps
• Malignant tumors:
  • Most common: adenocarcinomas (95%)
  • Others: carcinoid tumors, lymphomas, and squamous cell carcinomas

Risk Factors

• Age: 90% of cases occur in people over 50
• Family history: 1st-degree relatives with colorectal cancer
• Diet: low in fiber, high in fat and red meat
• Inflammatory bowel disease: ulcerative colitis and Crohn's disease
• Previous radiation therapy

Pathogenesis

• Adenoma-carcinoma sequence: benign adenomas progress to malignant adenocarcinomas
• Genetic mutations: APC, KRAS, and TP53 genes
• Epigenetic changes: DNA methylation and histone modifications

Clinical Features

• Asymptomatic: often diagnosed incidentally
• Symptoms:
  • Rectal bleeding
  • Changes in bowel habits
  • Abdominal pain
  • Weight loss
• Signs: palpable mass, anemia, and bowel obstruction

Diagnosis

• Endoscopy: colonoscopy and sigmoidoscopy
• Imaging: CT and MRI scans
• Biopsy: histopathological examination

Treatment

• Surgical resection: partial colectomy or total colectomy
• Adjuvant therapy: chemotherapy and radiation therapy
• Palliative care: for advanced or metastatic disease

Prognosis

• 5-year survival rate: 65% for localized disease, 13% for distant metastases
• Recurrence rate: 30-40% within 5 years

Types of Tumors

• Benign tumors are the most common, with adenomas (polyps) being the most frequent type
• Other types of benign tumors include lipomas, leiomyomas, and inflammatory polyps
• Malignant tumors, which account for 95% of cases, are predominantly adenocarcinomas
• Other types of malignant tumors include carcinoid tumors, lymphomas, and squamous cell carcinomas

Risk Factors

• Age is a significant risk factor, with 90% of cases occurring in people over 50
• Having a 1st-degree relative with colorectal cancer increases the risk
• A diet low in fiber and high in fat and red meat is also a risk factor
• Inflammatory bowel disease, such as ulcerative colitis and Crohn's disease, increases the risk
• Previous radiation therapy is another risk factor

Pathogenesis

• The adenoma-carcinoma sequence is a process where benign adenomas progress to malignant adenocarcinomas
• Genetic mutations in genes such as APC, KRAS, and TP53 contribute to the development of colorectal cancer
• Epigenetic changes, including DNA methylation and histone modifications, also play a role

Clinical Features

• Often, colorectal cancer is asymptomatic and diagnosed incidentally
• Symptoms may include rectal bleeding, changes in bowel habits, abdominal pain, and weight loss
• Signs may include a palpable mass, anemia, and bowel obstruction

Diagnosis

• Endoscopy, including colonoscopy and sigmoidoscopy, is used to diagnose colorectal cancer
• Imaging tests, such as CT and MRI scans, are also used
• Biopsy, involving histopathological examination, is necessary to confirm the diagnosis

Treatment

• Surgical resection, including partial colectomy or total colectomy, is often the primary treatment
• Adjuvant therapy, including chemotherapy and radiation therapy, may be used in addition to surgery
• Palliative care is used to manage symptoms and improve quality of life in advanced or metastatic disease

Prognosis

• The 5-year survival rate for localized disease is 65%, while it is 13% for distant metastases
• The recurrence rate is 30-40% within 5 years after treatment

Learn about the different types of tumors, including benign and malignant tumors, and the risk factors associated with colorectal cancer, such as age, family history, and diet.