24 Questions
What is the most common type of benign epithelial polyp in the colon?
Hyperplastic
What percentage of villous adenomas undergo malignant transformation?
40%
What is the mode of inheritance of Familial Adenomatous Polyposis (FAP)?
Autosomal dominant
What is the lifetime risk of developing colorectal cancer in FAP by age 50 years?
100%
What is the name of the syndrome associated with FAP, which includes desmoid tumors and osteomas?
Gardner's syndrome
What is the risk of colorectal cancer in patients with ulcerative colitis (UC) and Crohn's disease (CD) with pancolitis after 20 years?
8%
What is the type of polyp associated with Peutz-Jeghers syndrome?
Hamartomatous
What is a dietary factor that decreases the risk of colorectal cancer?
High vegetable fiber
Approximately what percentage of colorectal cancer cases arise in patients with a known family history of CRC?
20%
What is the typical location of tumors with poor prognosis and LOH pathway?
Left-sided tumors
What is the primary treatment option for Curative treatment of Colorectal Cancer (CRC)?
Surgical Treatment
What is the treatment for Caecal and ascending colon carcinoma?
Right Hemicolectomy (RHC)
What is the most common symptom of colorectal cancer?
Change in bowel habits
What is the treatment for Lower third cancer that is less than 2 cm above anal spincter?
Abdominoperineal Resection (APR)
What is the significance of DRE in colorectal cancer?
Detects lower rectal mass or ulcer
What is the definition of T1 in the TNM staging of CRC?
Tumor invades submucosa
What is the treatment for Early cancer (CIS and malignant polyp with no deeper invasion)?
Local Excision or Polypectomy
What is the investigation of choice for locating metastasis in Colorectal Cancer (CRC)?
PET Scan
What is the 5-year survival rate for Stage I colorectal cancer?
90-100%
What is the purpose of full colonoscopy in colorectal cancer?
To detect all of the above
What is the target therapy used in Colorectal Cancer (CRC)?
All of the above
What is the percentage of metachronous tumors detected by full colonoscopy?
10-40%
What is the investigation used for obstructing tumours in Colorectal Cancer (CRC)?
Water-soluble contrast study
What is the treatment for Locally advanced cancer or recurrent cancer?
Pelvic Exenteration
Study Notes
Colonic Tumors
- There are five types of benign epithelial polyps:
- Hyperplastic (regenerative) polyps
- Adenomatous polyps
- Hamartomatous polyps
- Inflammatory polyps
- Heterotopic polyps
Familial Adenomatous Polyposis (FAP)
- Autosomal dominant condition
- Accounts for about 1% of all colorectal cancer (CRC) cases
- Causes hundreds to thousands of adenomatous polyps
- Lifetime risk approaches 100% by age 50 years
- Associated with extraintestinal manifestations such as desmoid tumors, osteomas, and CNS tumors
Colorectal Carcinoma (CRC)
- Adenoma-carcinoma sequence
- Risk factors:
- Dietary factors (high animal fat, low fiber)
- Aging
- Sedentary lifestyle and obesity
- Inflammatory bowel disease (IBD)
- Cigarette smoking
- Ureterosigmoidostomy
- Acromegaly
- Pelvic irradiation
Genetics of CRC
- Approximately 20% of CRC cases have a known family history
- Oncogenes involved: K-ras, MYH
- Tumor-suppressor genes involved: APC, DCC, p53, PTEN
- Two major pathways: LOH pathway (left-sided tumors, poor prognosis) and Replication Error (RER) pathway (right-sided tumors, better prognosis)
Clinical Presentation of CRC
- Change in bowel habits
- Rectal bleeding
- Abdominal pain
- Iron deficiency anemia
- Unexplained weight loss
- Perianal pain
- Mucoid discharge
- Tenesmus
Examination of CRC
- Digital rectal examination (DRE)
- Abdominal examination (liver, ascites)
- Rarely: Sister Joseph or Verchow's node
TNM Staging of CRC
- Tumor stage (T): Tis (carcinoma in situ), T1 (invades submucosa), T2 (invades muscularis propria), T3 (invades nonperitonealized or perirectal tissues), T4 (invades other organs or perforates)
- Nodal stage (N): N0 (no lymph node metastasis), N1 (metastasis to 1-3 LNs), N2 (metastasis to >3 LNs), N3 (metastasis to any LN along a major named vascular trunk)
- Distant metastasis (M): M0 (no distant metastasis), M1 (distant metastasis present)
Modified Dukes' Classification
- Stage I: Tumor limited to bowel wall (5-year survival rate 90-100%)
- Stage II: Tumor extends beyond bowel wall (5-year survival rate 70%)
- Stage III: Any T stage with lymph node metastasis (5-year survival rate 30%)
- Stage IV: Distant metastases (5-year survival rate 10%)
Investigations of CRC
- Full colonoscopy
- Endoscopic ultrasound (EUS)
- Chest/abdominal/pelvic CT scan
- MRI
- Water-soluble contrast study (obstructing tumors)
- PET scan
- Preoperative CEA
Treatment of CRC
- Surgical treatment:
- Open surgery
- Laparoscopic surgery
- Hand-assisted laparoscopic surgery
- Totally laparoscopic surgery
- Laparoscopic colectomy
- Adjuvant therapy:
- Systemic chemotherapy
- Chemoradiation
- Intraoperative radiation therapy (usually brachytherapy)
- Target therapy (bevacizumab, erlotinib, cetuximab)
Prevention and Screening of CRC
- Early detection and removal of adenomatous polyps
- Screening programs for high-risk individuals
- Lifestyle modifications (diet, exercise, smoking cessation)
Learn about the different types of benign epithelial polyps, including hyperplastic, adenomatous, hamartomatous, inflammatory, and heterotopic polyps, as well as malignant transformation and polyp types.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
