Questions and Answers
What is the most common type of benign tumor?
Adenoma
What percentage of malignant tumors are adenocarcinomas?
95%
What is a major risk factor for colorectal cancer?
All of the above
What is the sequence of benign to malignant tumor progression?
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What is the most common symptom of colorectal cancer?
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What is the 5-year survival rate for localized colorectal cancer?
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Study Notes
Types of Tumors
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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
