Colorectal Neoplasms — MCQs
All of the following are risk factors for carcinoma of the gallbladder, EXCEPT -
A 50-year-old man suffering from left colon carcinoma. Which of the following is the MOST CHARACTERISTIC finding?
HNPCC has defect in which
All are true regarding familial adenomatous polyposis except which of the following?
What is the most characteristic finding in familial adenomatous polyposis (FAP)?
What is the treatment of choice for a patient presenting with carcinoma of the rectum and obstruction in an emergency setting?
A 52 year old male patient comes with history of rectal bleeding, alteration in bowel habits and tenesmus. The ideal investigation would be:
A colonic carcinoma involving muscularis propria, with one or two nodes involved with a solitary metastasis in the liver, the TNM stage would be:
In a 65 year old, double contrast barium enema shows cancer of colon with an apple core appearance. Colonoscopic biopsy shows adenocarcinoma. What will be the next step of management?
A 22 year old young man came with history of occasional bleeding per rectum. On colonoscopy, numerous sessile polyps were seen in descending and sigmoid colon. On family history his elder brother was operated for thyroid malignancy. The young man should be advised:
Colorectal Neoplasms Indian Medical PG Practice Questions and MCQs
Question 1: All of the following are risk factors for carcinoma of the gallbladder, EXCEPT -
- A. Adenomatous gall bladder polyps
- B. Choledochal cysts
- C. Oral contraceptives (Correct Answer)
- D. Typhoid carriers
Explanation: ***Oral contraceptives*** - While **oral contraceptives** can increase the risk of **gallstones**, they are not directly recognized as a specific risk factor for **gallbladder carcinoma**. - The impact of oral contraceptives on gallbladder cancer risk is generally considered to be minor or non-existent compared to established risk factors. *Typhoid carriers* - **Chronic asymptomatic carriers of Salmonella Typhi** have a significantly increased risk of developing **gallbladder carcinoma**, likely due to chronic inflammation and cellular damage. - The bacteria can reside in the gallbladder for years, leading to a persistent inflammatory state and genetic mutations. *Adenomatous gall bladder polyps* - **Adenomatous polyps** in the gallbladder are considered **premalignant lesions**, especially if they are larger than 10 mm, and are associated with an increased risk of progression to adenocarcinoma. - Their presence indicates a need for careful monitoring and often surgical removal due to their malignant potential. *Choledochal cysts* - **Choledochal cysts**, congenital dilations of the bile ducts, are well-established risk factors for **cholangiocarcinoma** (bile duct cancer) and, less commonly, **gallbladder carcinoma**. - The stasis and reflux of bile within these cysts lead to chronic irritation and inflammation, increasing the risk of malignant transformation.
Question 2: A 50-year-old man suffering from left colon carcinoma. Which of the following is the MOST CHARACTERISTIC finding?
- A. Apple core sign on imaging (Correct Answer)
- B. Bleeding can occur
- C. Stools may be liquid
- D. Mass may be present
Explanation: ***Apple core sign on imaging*** - The **"apple core"** or **"napkin ring" sign** is a classic radiologic finding in **left-sided colon carcinoma** on barium enema or CT, indicating circumferential narrowing of the bowel lumen due to tumor growth. - This characteristic appearance results from the tumor encircling and constricting the colon, resembling an apple core after the core has been removed. *Bleeding can occur* - While bleeding is a common symptom of **colorectal cancer** (both left and right-sided), it is a **non-specific finding** and not the *most characteristic* for left colon carcinoma. - **Occult blood** in stool is more common with right-sided lesions, whereas visible **hematochezia** can occur with left-sided lesions. *Stools may be liquid* - **Liquid stools** are not a characteristic finding of left colon carcinoma; rather, **obstruction** can lead to **tenesmus** and **pencil-thin stools** or **constipation** due to tumor narrowing the lumen. - Diarrhea can sometimes be observed in more proximal colon tumors, but it's not specific to left colon cancer. *Mass may be present* - A **mass** often develops in **colorectal cancer**, but it is a **general feature** of many cancers and is not the *most characteristic* finding specifically for left colon carcinoma. - A palpable mass is more common in **right-sided tumors**, which can grow larger before causing obstructive symptoms.
Question 3: HNPCC has defect in which
- A. Mismatch repair gene (Correct Answer)
- B. Base excision repair
- C. Point mutation
- D. Nucleotide excision repair
Explanation: ***Mismatch repair gene*** - **HNPCC (hereditary non-polyposis colorectal cancer)**, also known as Lynch syndrome, is caused by inherited mutations in genes responsible for **DNA mismatch repair** [1]. - These genes, such as **MLH1, MSH2, MSH6, and PMS2**, normally correct errors that occur during DNA replication, preventing the accumulation of mutations. *Base pair excision* - **Base excision repair** is a distinct DNA repair pathway that primarily fixes small base lesions, such as damaged or modified bases. - This mechanism is not primarily implicated in the development of HNPCC. *Point mutation* - A **point mutation** refers to a single nucleotide change in a DNA sequence, which can be the *result* of a defective repair mechanism but is not the defect itself. - While mismatch repair defects lead to an increased rate of point mutations, the underlying *defect* in HNPCC is in the repair system, not in the mutation type. *Nucleotide excision* - **Nucleotide excision repair** is a major pathway for removing bulky, helix-distorting DNA lesions, such as those caused by UV radiation. - Defects in this pathway are associated with conditions like **xeroderma pigmentosum**, not HNPCC. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, p. 817.
Question 4: All are true regarding familial adenomatous polyposis except which of the following?
- A. Associated endocrine involvement can be present
- B. Multiple duodenal polyps
- C. Autosomal recessive (Correct Answer)
- D. More > 100 polyps in the colon
Explanation: ***Autosomal recessive*** - **Familial adenomatous polyposis (FAP)** is inherited in an **autosomal dominant** pattern, not autosomal recessive. - It is caused by a germline mutation in the **APC gene** on chromosome 5q21-q22. *Associated endocrine involvement can be present* - **Gardner syndrome**, a variant of FAP, is associated with **extracolonic manifestations**, including benign osteomas, desmoid tumors, and epidermal cysts, which can be linked to endocrine disturbances [1]. - Other manifestations can include **adrenal adenomas** and **thyroid cancer**, reflecting potential widespread systemic involvement. *Multiple duodenal polyps* - FAP is characterized by the development of numerous **adenomatous polyps** throughout the gastrointestinal tract, especially in the **colon and rectum**. - **Duodenal polyps**, particularly in the periampullary region, are common and can malignant change, requiring regular surveillance [1]. *More > 100 polyps in the colon* - The defining feature of FAP is the presence of **hundreds to thousands of colorectal adenomatous polyps**, often exceeding 100. - These polyps have a nearly **100% risk of malignant transformation** into colorectal cancer if left untreated.
Question 5: What is the most characteristic finding in familial adenomatous polyposis (FAP)?
- A. Predominantly affects males
- B. Autosomal dominant inheritance (Correct Answer)
- C. If not treated, FAP has a very high risk of progressing to malignancy.
- D. Males and females are affected equally
Explanation: ***Familial adenomatous polyposis affects both males and females equally.*** - Familial adenomatous polyposis (FAP) follows an **autosomal dominant inheritance pattern**, therefore affecting both genders. - It typically presents with **hundreds to thousands of adenomatous polyps** in the colon, leading to a significant risk for colon cancer if untreated [1]. *If not treated, it progresses to malignancy in nearly all cases.* - While untreated FAP has a high risk for colorectal cancer, it does not mean **all cases** progress to malignancy; some may be managed effectively. - Regular screening and prophylactic surgery can significantly **reduce** the malignant potential associated with the condition [1]. *Males and females are affected equally.* - While FAP affects males and females, the tendency for development of certain cancers may vary; stating it affects them **equally** could be misleading due to varying cancer risks. - The inheritance and clinical implications do not make a distinction based on gender despite equal prevalence. *Autosomal dominant inheritance.* - This statement about inheritance is indeed **true**, but it is not the correct statement regarding FAP's equality in affecting genders. - The **mutated APC gene** is responsible for FAP, leading to the widespread formation of polyps and the risk of colon cancer [1].
Question 6: What is the treatment of choice for a patient presenting with carcinoma of the rectum and obstruction in an emergency setting?
- A. Total colectomy
- B. Hartmann's procedure (Correct Answer)
- C. Defunctioning colostomy
- D. Left hemi-colectomy
Explanation: ***Hartmann's procedure*** - In an emergency setting with **obstructing carcinoma of the rectum**, Hartmann's procedure is the **treatment of choice**. - This procedure involves **resection of the tumor** with formation of an **end colostomy** and closure of the distal rectal stump. - It achieves **dual objectives**: relieves the obstruction AND removes the primary tumor, allowing proper oncological staging and planning of adjuvant therapy. - While more extensive than simple diversion, it is the **standard emergency operation** for obstructing left-sided and rectal cancers in patients who can tolerate resection. - The colostomy can be reversed later after adjuvant treatment (if needed), though many remain permanent. *Defunctioning colostomy* - A proximal diverting colostomy only diverts the fecal stream without addressing the primary tumor. - This is a **temporizing measure**, not definitive treatment, and leaves the malignancy in situ. - It may be considered in **highly unstable patients** or for purely **palliative** intent when resection is not feasible. - Requires a second major operation for definitive tumor resection, increasing overall morbidity. *Total colectomy* - This involves removing the entire colon and is performed for conditions like **familial adenomatous polyposis** or **synchronous colon cancers**. - Not indicated for isolated rectal cancer with obstruction. - Would be excessively extensive and carry unnecessary morbidity in this setting. *Left hemi-colectomy* - This procedure removes the left colon (descending and sigmoid) but typically does not include the rectum. - Not appropriate for **rectal cancer**, as it would not address the primary pathology. - Used for tumors of the descending or sigmoid colon, not rectum.
Question 7: A 52 year old male patient comes with history of rectal bleeding, alteration in bowel habits and tenesmus. The ideal investigation would be:
- A. Contrast-enhanced CT scan
- B. Fecal occult blood test
- C. Colonoscopy (Correct Answer)
- D. Ultrasonogram
Explanation: ***Colonoscopy*** - **Colonoscopy** is the gold standard for investigating symptoms like rectal bleeding, altered bowel habits, and tenesmus, as it allows for direct visualization of the entire colon and rectum. - It enables **biopsy of suspicious lesions** for histopathological diagnosis, which is crucial for confirming conditions like colorectal cancer or inflammatory bowel disease. *Contrast-enhanced CT scan* - A **contrast-enhanced CT scan** is primarily used for **staging known malignancies** and assessing for distant metastases, not as a primary diagnostic tool for initial symptoms. - While it can identify large masses, it might miss smaller lesions and does not allow for tissue biopsy. *Fecal occult blood test* - A **fecal occult blood test** screens for blood in the stool, which indicates gastrointestinal bleeding but does not pinpoint the source or cause. - It has **low sensitivity and specificity** for diagnosing underlying conditions like colorectal cancer or inflammatory bowel disease and is mainly a screening tool. *Ultrasonogram* - An **ultrasonogram** is generally not effective for evaluating the colon and rectum due to bowel gas interference. - It is more commonly used for investigating abdominal organs like the liver, gallbladder, and kidneys, or for pelvic pathology, but not the primary investigation for these colorectal symptoms.
Question 8: A colonic carcinoma involving muscularis propria, with one or two nodes involved with a solitary metastasis in the liver, the TNM stage would be:
- A. T2 N1 M1 (Correct Answer)
- B. T1 N2 M1
- C. T1 N1 M1
- D. T2 N2 M1
Explanation: ***T2 N1 M1*** **(Correct Answer)** - **T2** indicates the tumor invades the **muscularis propria** in the TNM classification for colorectal cancer. - **N1** signifies involvement of **one to three regional lymph nodes**, which corresponds to "one or two nodes involved" in the question. - **M1** denotes the presence of **distant metastasis**, specifically a "solitary metastasis in the liver" as described. *T1 N2 M1* - **T1** describes a tumor that invades the **submucosa** but not the muscularis propria, which is less advanced than the scenario described. - **N2** would imply involvement of **four or more regional lymph nodes**, contradicting the "one or two nodes involved" stated in the question. *T1 N1 M1* - **T1** indicates invasion into the **submucosa**, not reaching the muscularis propria as specified in the case description. - The **N1** and **M1** components are consistent with the nodal involvement and distant metastasis, but the **T stage** is incorrect. *T2 N2 M1* - While **T2** is correct for invasion into the muscularis propria, **N2** incorrectly implies involvement of **four or more regional lymph nodes**. - The question states "one or two nodes involved," making **N1** the appropriate nodal classification.
Question 9: In a 65 year old, double contrast barium enema shows cancer of colon with an apple core appearance. Colonoscopic biopsy shows adenocarcinoma. What will be the next step of management?
- A. Surgery
- B. Radiotherapy
- C. Chemotherapy
- D. CECT to stage disease (Correct Answer)
Explanation: ***CECT to stage disease*** - **CECT (Contrast-Enhanced CT) of chest, abdomen, and pelvis is the essential next step** after histological confirmation of colon adenocarcinoma. - **Staging is mandatory** before any treatment decision to determine: - **Local extent** of tumor (T stage) - **Lymph node involvement** (N stage) - **Distant metastases** (M stage - liver, lungs, peritoneum) - **Resectability** and surgical planning - Even with the "apple core" appearance indicating an advanced primary tumor, **treatment decisions cannot be made without knowing the overall disease burden**. - **CEA (Carcinoembryonic Antigen) levels** are also typically obtained during staging. *Surgery* - **Surgical resection is the definitive treatment** for localized, resectable colon cancer and would be performed **after staging**, not before. - Surgery involves removing the tumor with adequate margins and regional lymphadenectomy. - However, **staging must precede surgery** to: - Determine if the disease is metastatic (which would change surgical approach) - Plan the extent of resection - Counsel the patient appropriately - Decide on neoadjuvant therapy if indicated - The "apple core" appearance suggests an advanced primary but does not indicate acute obstruction requiring emergency surgery in this stable patient who has already undergone barium enema and colonoscopy. *Chemotherapy* - **Chemotherapy** is typically given as: - **Adjuvant therapy** after surgery for stage III (node-positive) or high-risk stage II disease - **Palliative therapy** for metastatic (stage IV) disease - **Neoadjuvant therapy** is not standard for colon cancer (unlike rectal cancer) - Chemotherapy is not the immediate next step; staging and then surgery (if resectable) come first. *Radiotherapy* - **Radiotherapy has limited role in colon cancer** (unlike rectal cancer where it is commonly used). - It may be used for: - **Palliation** of symptoms (pain, bleeding) in advanced disease - Rare cases of **locally advanced unresectable disease** - It is not a primary treatment modality and is not the next step in this case.
Question 10: A 22 year old young man came with history of occasional bleeding per rectum. On colonoscopy, numerous sessile polyps were seen in descending and sigmoid colon. On family history his elder brother was operated for thyroid malignancy. The young man should be advised:
- A. Prophylactic anterior resection
- B. Prophylactic panproctocolectomy (Correct Answer)
- C. Surveillance colonoscopy every 6 months
- D. Colonoscopic removal of all polyps
Explanation: ***Prophylactic panproctocolectomy*** - This patient presents with multiple sessile polyps in the descending and sigmoid colon, along with a family history of **thyroid malignancy** in his brother. This constellation of findings is highly suggestive of **Familial Adenomatous Polyposis (FAP)**, specifically **Gardner syndrome**, which is a variant of FAP associated with extracolonic manifestations like thyroid tumors. - Due to the high risk of **colorectal cancer** development in FAP (nearly 100% by age 40 without intervention), **prophylactic panproctocolectomy** is the recommended treatment to prevent progression to malignancy. *Prophylactic anterior resection* - An anterior resection typically involves removing only a segment of the colon, which would be insufficient for a patient with FAP, as polyps can develop throughout the entire colon and rectum. - This procedure would leave a significant portion of the colon at risk for **neoplastic transformation**, necessitating further surgeries or intense surveillance. *Surveillance colonoscopy every 6 months* - While surveillance is crucial in risk assessment, for diagnosed FAP, particularly with symptomatic polyps and a family history suggestive of a syndrome, surveillance alone is inadequate due to the **high and inevitable risk of cancer**. - Delaying definitive surgical intervention would expose the patient to a very high probability of developing **colorectal carcinoma**. *Colonoscopic removal of all polyps* - Given the presence of **numerous sessile polyps**, endoscopic polypectomy would be impractical, incomplete, and would likely miss microscopic or nascent lesions. - This approach offers only temporary management and does not address the underlying genetic predisposition to continuous polyp formation and high malignancy risk.
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