COLORECTAL CA

Question 1

Which type of polyp is clearly considered premalignant and has the potential to evolve into colorectal cancer?

A) Juvenile polyp
B) Hyperplastic polyp
C) Adenomatous polyp
D) Hamartoma

Answer 1

Correct Answer: C) Adenomatous polyp

Rationale:
Adenomatous polyps are considered premalignant, as they have the potential to evolve into colorectal cancer, unlike juvenile or hyperplastic polyps, which are non-neoplastic.

Question 2

Which of the following molecular events is most closely associated with the development of colorectal cancer?

A) Hypomethylation of DNA leading to gene activation
B) Point mutations in the K-ras proto-oncogene
C) Allelic loss at the APC gene on chromosome 5
D) All of the above

Answer 2

Correct Answer: D) All of the above

Rationale:
The development of colorectal cancer involves multiple molecular events, including point mutations in K-ras, hypomethylation of DNA, and allelic loss at tumor-suppressor genes such as APC, DCC, and p53.

Question 3

Which type of adenomatous polyp has the highest likelihood of progressing to invasive cancer?

A) Tubular adenoma
B) Villous adenoma
C) Tubulovillous adenoma
D) Serrated adenoma

Answer 3

Correct Answer: B) Villous adenoma

Rationale:
Villous adenomas, particularly when they are sessile, become malignant more than three times as often as tubular adenomas, making them the highest risk type.

Question 4

How often should colonoscopy be repeated for patients with adenomatous polyps, even in the absence of previously documented malignancy?

A) Every year
B) Every 3 years
C) Every 5 years
D) Every 10 years

Answer 4

Correct Answer: B) Every 3 years

Rationale:
Patients with adenomatous polyps are at a higher-than-average risk for developing another adenoma or colorectal carcinoma, so colonoscopy should be repeated periodically, typically every 3 years.

Question 5

Which of the following statements is true about sessile, serrated polyps compared to pedunculated polyps?

A) Sessile, serrated polyps are less likely to develop into cancer
B) Sessile, serrated polyps are more likely to develop into cancer
C) Sessile, serrated polyps are always benign
D) Sessile, serrated polyps are smaller than pedunculated polyps

Answer 5

Correct Answer: B) Sessile, serrated polyps are more likely to develop into cancer

Rationale:
Sessile, serrated polyps (flat-based) are more likely to develop into invasive cancers compared to pedunculated polyps (stalked), making them higher-risk lesions.

Question 6

Which hypothesis suggests that animal fats in the diet increase colorectal cancer risk?

A) High sugar intake hypothesis
B) Insulin resistance hypothesis
C) Animal fat and microbiome hypothesis
D) Fiber intake hypothesis

Answer 6

Correct Answer: C) Animal fat and microbiome hypothesis

Rationale:
This hypothesis suggests that animal fats from red meats and processed meats alter the gut microbiome, leading to the conversion of normal bile acids into carcinogens, which may increase colorectal cancer risk.

Question 7

What is the role of insulin resistance in the development of colorectal cancer?

A) It lowers circulating levels of insulin-like growth factor type I (IGF-I)
B) It causes physical inactivity, which decreases colorectal cancer risk
C) It leads to higher levels of insulin-like growth factor type I (IGF-I), stimulating proliferation of the intestinal mucosa
D) It has no role in colorectal cancer development

Answer 7

Correct Answer: C) It leads to higher levels of insulin-like growth factor type I (IGF-I), stimulating proliferation of the intestinal mucosa

Rationale:
Insulin resistance, common in obese individuals, leads to increased levels of insulin and IGF-I, which can stimulate the proliferation of the intestinal mucosa, contributing to colorectal cancer risk.

Question 8

What does recent research suggest about the role of dietary fiber in preventing colorectal cancer?

A) High-fiber diets significantly reduce colorectal cancer risk
B) High-fiber diets prevent the recurrence of colorectal adenomas
C) The results of randomized trials and case-controlled studies fail to support the role of dietary fiber in colorectal cancer prevention
D) Fiber intake is the most important dietary factor for colorectal cancer prevention

Answer 8

Correct Answer: C) The results of randomized trials and case-controlled studies fail to support the role of dietary fiber in colorectal cancer prevention

Rationale:
Recent studies and randomized trials have failed to show that high dietary fiber or high fruit and vegetable intake prevent the recurrence of colorectal adenomas or colorectal cancer, despite prior beliefs.

Question 9

Which dietary factor is primarily implicated in the development of colorectal cancer according to the majority of epidemiologic evidence?

A) High fiber intake
B) High animal fat and calorie intake
C) High carbohydrate intake
D) High vegetable protein intake

Answer 9

Correct Answer: B) High animal fat and calorie intake

Rationale:
Epidemiologic evidence consistently points to diets high in animal fat and calories as major etiologic factors for colorectal cancer, supporting the importance of dietary choices in cancer prevention.

Question 10

What is the genetic cause of MYH-associated polyposis (MAP)?

A) A mutation in the APC gene
B) A biallelic mutation in the MUT4H gene
C) A mutation in the BRCA1 gene
D) A mutation in the K-ras gene

Answer 10

Correct Answer: B) A biallelic mutation in the MUT4H gene

Rationale:
MYH-associated polyposis (MAP) is caused by a biallelic mutation in the MUT4H gene, which leads to a hereditary syndrome resembling polyposis coli or colorectal cancer.

Question 11

What is the recommended age for starting colonoscopic surveillance for individuals with MYH-associated polyposis (MAP)?

A) Age 15–20 years
B) Age 25–30 years
C) Age 40–50 years
D) Age 50–60 years

Answer 11

Correct Answer: B) Age 25–30 years

Rationale:
Annual to biennial colonoscopic surveillance is generally recommended for individuals with MYH-associated polyposis (MAP), starting at age 25–30 years.

Question 12

Which of the following is a key clinical feature of MYH-associated polyposis (MAP)?

A) Colorectal cancer in older individuals
B) Polyposis coli or colorectal cancer in younger individuals without polyposis
C) Elevated risk for breast cancer
D) A single colorectal polyp in early adulthood

Answer 12

Correct Answer: B) Polyposis coli or colorectal cancer in younger individuals without polyposis

Rationale:
MYH-associated polyposis (MAP) often presents with polyposis coli or colorectal cancer in younger individuals, and it may occur without the classic polyposis seen in other hereditary syndromes.

Question 13

How is MYH-associated polyposis (MAP) inherited?

A) Autosomal dominant
B) X-linked recessive
C) Autosomal recessive
D) Mitochondrial inheritance

Answer 13

Correct Answer: C) Autosomal recessive

Rationale:
MYH-associated polyposis (MAP) is inherited in an autosomal recessive manner, meaning both copies of the gene must be mutated for the condition to manifest.

Question 14

Which genes are commonly mutated in Lynch syndrome?

A) BRCA1 and BRCA2
B) hMSH2 and hMLH1
C) APC and K-ras
D) TP53 and PTEN

Answer 14

Correct Answer: B) hMSH2 and hMLH1

Rationale:
Lynch syndrome is associated with germline mutations in the hMSH2 and hMLH1 genes, which are involved in DNA mismatch repair and lead to DNA instability.

Question 14

What age group typically experiences the development of colorectal adenocarcinoma in Lynch syndrome?

A) 60–70 years
B) 50–60 years
C) <50 years
D) >70 years

Answer 14

Correct Answer: C) <50 years

Rationale:
In Lynch syndrome, the median age for the development of colorectal adenocarcinoma is less than 50 years, which is 10–15 years younger than the general population’s median age.

Question 15

Which of the following is characteristic of polyposis coli (familial polyposis of the colon)?

A) The development of a few adenomatous polyps scattered throughout the colon
B) The appearance of thousands of adenomatous polyps throughout the large bowel
C) The development of only distal colon polyps
D) Absence of any associated cancers

Answer 15

Correct Answer: B) The appearance of thousands of adenomatous polyps throughout the large bowel

Rationale:
Polyposis coli is characterized by the appearance of thousands of adenomatous polyps throughout the large bowel, a hallmark feature of this autosomal dominant condition.

Question 16

What is the genetic cause of polyposis coli?

A) A mutation in the TP53 gene
B) A deletion on the long arm of chromosome 5, including the APC gene
C) A duplication of the BRCA1 gene
D) A mutation in the MLH1 gene

Answer 16

Correct Answer: B) A deletion on the long arm of chromosome 5, including the APC gene

Rationale:
Polyposis coli results from a deletion on the long arm of chromosome 5, which includes the APC gene. This deletion leads to the absence of tumor-suppressor proteins, promoting neoplastic growth.

Question 17

What is the hallmark feature of Gardner’s syndrome, a subset of polyposis coli?

A) Development of colorectal cancer by age 40
B) Presence of soft tissue and bony tumors, congenital hypertrophy of the retinal pigment epithelium, mesenteric desmoid tumors, and ampullary cancers
C) Development of only gastrointestinal polyps
D) Complete absence of colonic polyps

Answer 17

Correct Answer: B) Presence of soft tissue and bony tumors, congenital hypertrophy of the retinal pigment epithelium, mesenteric desmoid tumors, and ampullary cancers

Rationale:
Gardner’s syndrome is characterized by the presence of additional features beyond polyposis coli, including soft tissue and bony tumors, mesenteric desmoid tumors, and ampullary cancers.

Question 18

What is the recommended treatment for polyposis coli to prevent the development of colorectal cancer?

A) Annual colonoscopy starting at age 40
B) Nonsteroidal anti-inflammatory drugs (NSAIDs) alone
C) Total colectomy
D) Chemotherapy for polyp regression

Answer 18

Correct Answer: C) Total colectomy

Rationale:
The primary treatment for polyposis coli to prevent colorectal cancer is total colectomy, as colorectal cancer will develop in almost all untreated patients by age 40.

Question 19

Which of the following is characteristic of Turcot’s syndrome?

A) The presence of colorectal polyps without associated central nervous system tumors
B) The appearance of malignant tumors of the central nervous system (e.g., medulloblastomas or glioblastomas) accompanying polyposis coli
C) A mutation in the BRCA1 gene leading to both breast and ovarian cancers
D) The development of colorectal cancer in individuals with no family history of polyps

Answer 19

Correct Answer: B) The appearance of malignant tumors of the central nervous system (e.g., medulloblastomas or glioblastomas) accompanying polyposis coli

Rationale:
Turcot’s syndrome is characterized by the combination of polyposis coli (familial adenomatous polyposis) and the presence of malignant central nervous system tumors such as medulloblastomas or glioblastomas. The presence of these two features—colorectal polyps and CNS tumors—defines the syndrome.

Question 20

Which of the following is the optimal treatment strategy when a malignant lesion is detected in the large bowel?

A) Immediate chemotherapy without surgery
B) Total resection of the tumor with preoperative evaluation for metastatic disease
C) Primary tumor resection only in asymptomatic patients with metastatic disease
D) Observation and periodic CT scans without surgery

Answer 20

Correct Answer: B) Total resection of the tumor with preoperative evaluation for metastatic disease

Rationale:
When a malignant lesion is detected in the large bowel, the optimal treatment is the total resection of the tumor. This is preceded by an evaluation for metastatic disease, which includes a thorough physical examination, liver function tests, plasma CEA levels, and a CT scan of the chest, abdomen, and pelvis. Additionally, a preoperative colonoscopy is recommended to identify synchronous neoplasms or polyps.

Question 21

What is the primary reason for performing a colonoscopy of the entire large bowel before surgery in patients with a malignant bowel lesion?

A) To evaluate the presence of abdominal metastases
B) To assess the bowel for synchronous neoplasms and/or polyps
C) To confirm the presence of colon cancer
D) To assess the function of the bowel

Answer 21

Correct Answer: B) To assess the bowel for synchronous neoplasms and/or polyps

Rationale:
A complete colonoscopy before surgery is recommended to identify synchronous neoplasms and/or polyps in patients with malignant bowel lesions. This helps in identifying additional areas that may need treatment and ensures comprehensive management of the disease.

Question 22

How frequently should plasma CEA levels be measured in the first 3 years after colorectal cancer resection?

A) Every month
B) Every 6 months
C) Every 3 months
D) Annually

Answer 22

Correct Answer: C) Every 3 months

Rationale:
Plasma CEA levels should be measured at 3-month intervals after colorectal cancer resection due to the test’s sensitivity in detecting undetectable tumor recurrence. This allows for early detection of potential recurrences that may not be visible through imaging.

Question 23

Why is periodic CT scanning of the abdomen recommended annually for the first 3 postoperative years in colorectal cancer patients?

A) To evaluate tumor recurrence in an early, asymptomatic stage
B) To monitor liver function post-surgery
C) To check for surgical site infection
D) To evaluate for complications like bowel obstruction

Answer 23

Correct Answer: A) To evaluate tumor recurrence in an early, asymptomatic stage

Rationale:
The value of periodic CT scans is to detect any early, asymptomatic indications of tumor recurrence. While their use is uncertain in some contexts, annual CT scans are recommended for the first 3 years after surgery for colorectal cancer to ensure timely detection of recurrence.

Question 24

Which chemotherapy drug remains the backbone of treatment for colorectal cancer? A) Irinotecan B) Oxaliplatin C) 5-Fluorouracil (5-FU) D) Leucovorin

Answer 24

Correct Answer: C) 5-Fluorouracil (5-FU) Rationale: 5-FU remains the backbone of chemotherapy treatment for colorectal cancer, with partial responses observed in 15–20% of patients. It is a key component in various combination regimens, such as FOLFOX and FOLFIRI, and continues to play a central role in therapy despite the addition of other agents.

Question 25

How does folinic acid (leucovorin) enhance the efficacy of 5-FU in colorectal cancer treatment? A) By directly inhibiting tumor growth B) By enhancing the binding of 5-FU to its target enzyme, thymidylate synthase C) By reducing the side effects of 5-FU D) By preventing the development of metastases

Answer 25

Correct Answer: B) By enhancing the binding of 5-FU to its target enzyme, thymidylate synthase Rationale: Folinic acid (leucovorin) improves the efficacy of 5-FU by enhancing its binding to thymidylate synthase, the target enzyme of 5-FU. This interaction increases the effectiveness of 5-FU in inhibiting tumor growth.

Question 26

Which of the following is a major side effect of irinotecan when used in combination with 5-FU and leucovorin (FOLFIRI)? A) Nausea B) Diarrhea C) Fatigue D) Neuropathy

Answer 26

Correct Answer: B) Diarrhea Rationale: Diarrhea is the major side effect of irinotecan, which is used as part of the FOLFIRI regimen. This side effect can be severe and requires careful management.

Question 27

Which chemotherapy regimen combines oxaliplatin with 5-FU and leucovorin to treat metastatic colorectal cancer? A) FOLFOX B) FOLFIRI C) FOLVIR D) FLOX

Answer 27

Correct Answer: A) FOLFOX Rationale: The FOLFOX regimen combines oxaliplatin, 5-FU, and leucovorin for the treatment of metastatic colorectal cancer. This combination improves response rates and is used as an initial treatment for patients with metastatic disease.

Question 28

Which side effect is most commonly associated with oxaliplatin in the FOLFOX regimen? A) Sensory neuropathy B) Nausea and vomiting C) Hair loss D) Fever

Answer 28

Correct Answer: A) Sensory neuropathy Rationale: Sensory neuropathy is the most common side effect associated with oxaliplatin. This side effect can be dose-dependent and may resolve after the cessation of therapy. It is a notable concern in patients undergoing FOLFOX treatment.

Question 29

What is the approximate median survival for patients with metastatic colorectal cancer treated with FOLFIRI or FOLFOX? A) 1 year B) 2 years C) 5 years D) 10 years

Answer 29

Correct Answer: B) 2 years Rationale: For patients with metastatic colorectal cancer, treatment with FOLFIRI or FOLFOX regimens typically results in a median survival of around 2 years. Both regimens are equally effective in improving survival.

Question 30

Which of the following monoclonal antibodies targets the epidermal growth factor receptor (EGFR) in the treatment of advanced colorectal cancer? A) Bevacizumab B) Cetuximab C) Erlotinib D) Sunitinib

Answer 30

Correct Answer: B) Cetuximab Rationale: Cetuximab (Erbitux) is a monoclonal antibody that targets the epidermal growth factor receptor (EGFR). This receptor is involved in tumor cell growth and proliferation, and cetuximab has shown benefits in patients with advanced colorectal cancer.

Question 31

Which of the following side effects is commonly associated with the use of cetuximab and panitumumab? A) Diarrhea B) Acne-like rash C) Nausea D) Hair loss

Answer 31

Correct Answer: B) Acne-like rash Rationale: The use of cetuximab and panitumumab can lead to an acne-like rash. The development and severity of this rash have been correlated with the likelihood of antitumor efficacy, meaning that patients with a more severe rash may experience better therapeutic responses.

Question 32

Monoclonal antibodies like cetuximab and panitumumab are not effective in approximately what percentage of colorectal cancer cases due to mutations in the ras or b-raf genes? A) 10% B) 25% C) 50% D) 65%

Answer 32

Correct Answer: D) 65% Rationale: Cetuximab and panitumumab are not effective in around 65% of colorectal cancer cases because of mutations in the ras or b-raf genes. These mutations prevent the effectiveness of EGFR-targeting therapies.

Question 33

Which monoclonal antibody targets vascular endothelial growth factor (VEGF) in the treatment of colorectal cancer? A) Bevacizumab B) Cetuximab C) Panitumumab D) Erlotinib

Answer 33

Correct Answer: A) Bevacizumab Rationale: Bevacizumab (Avastin) targets vascular endothelial growth factor (VEGF), which plays a role in angiogenesis, the formation of new blood vessels that supply tumors. Bevacizumab acts as an antiangiogenesis agent, improving the outcome when added to chemotherapy regimens like FOLFOX and irinotecan-based treatments.

Question 34

Which of the following adverse effects is commonly associated with the use of bevacizumab in colorectal cancer treatment? A) Hypertension B) Rash C) Nausea D) Hearing loss

Answer 34

Correct Answer: A) Hypertension Rationale: Hypertension is a common side effect associated with bevacizumab treatment. Other side effects include proteinuria and an increased likelihood of thromboembolic events.

Question 35

Which of the following monoclonal antibodies is most likely to reverse resistance to cytotoxic chemotherapy in colorectal cancer? A) Panitumumab B) Cetuximab C) Bevacizumab D) Erlotinib

Answer 35

Correct Answer: B) Cetuximab Rationale: Cetuximab has been shown to have therapeutic synergy with chemotherapeutic agents like irinotecan, even in patients previously resistant to this drug. This suggests that cetuximab can reverse cellular resistance to chemotherapy in some cases.