Colorectal Cancer Indian Medical PG Practice Questions and MCQs
Practice Indian Medical PG questions for Colorectal Cancer. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Colorectal Cancer Indian Medical PG Question 1: Which of the following statements are true?
1. Due to increasing mammography there occurs over diagnosis of breast carcinoma
2. Colon cancer screening is done by digital rectal examination
3. Oral cancer screening is done by visual inspection
4. Cervix cancer screening is done by a pap smear
- A. 1,2,3,4
- B. 4 only
- C. 1,3,4 (Correct Answer)
- D. 2,3,4
Colorectal Cancer Explanation: ***Correct: 1,3,4***
- **Statement 1 is TRUE**: Overdiagnosis is a well-documented consequence of increased mammography screening. It detects slow-growing tumors that might never have caused clinical symptoms or harm during a woman's lifetime, leading to unnecessary treatment and associated morbidities.
- **Statement 3 is TRUE**: Oral cancer screening primarily involves thorough visual inspection by a healthcare professional to identify suspicious lesions, ulcers, or color changes in the oral cavity.
- **Statement 4 is TRUE**: Cervical cancer screening is effectively done by Pap smear, which detects precancerous and cancerous cells.
- **Statement 2 is FALSE**: Digital rectal examination is NOT the primary screening method for colon cancer. Standard screening methods include colonoscopy, fecal occult blood testing (FOBT), and fecal immunochemical test (FIT).
*Incorrect: 1,2,3,4*
- While statements 1, 3, and 4 are true, statement 2 is incorrect. Digital rectal examination is not a primary or definitive screening method for colon cancer—it only examines the rectum and misses most of the colon.
*Incorrect: 4 only*
- While cervical cancer screening by Pap smear is true, this option is incomplete as it misses other true statements (1 and 3) regarding mammography overdiagnosis and oral cancer screening.
*Incorrect: 2,3,4*
- This option incorrectly includes statement 2. Colon cancer screening is NOT done by digital rectal examination. Proper screening methods include colonoscopy, FOBT, FIT, and flexible sigmoidoscopy.
Colorectal Cancer Indian Medical PG Question 2: Which of the following screening methods is NOT effective for early detection of cancer in asymptomatic women?
- A. Office endometrial washing for endometrial cancer
- B. USG in endometrial cancer
- C. CA-125 for ovarian cancer (Correct Answer)
- D. Pap smear for cervical cancer
Colorectal Cancer Explanation: ***CA-125 for ovarian cancer***
- While elevated in some ovarian cancers, **CA-125 lacks sufficient sensitivity and specificity** as a stand-alone screening tool for early detection in asymptomatic women.
- Its use for general population screening has **not been shown to reduce mortality** from ovarian cancer and can lead to **false positives** and unnecessary invasive procedures.
- Major trials (UKCTOCS, PLCO) have not demonstrated mortality benefit from CA-125 screening.
*Office endometrial washing for endometrial cancer*
- While this involves collecting cells from the uterine lining for cytological analysis, **endometrial washing/cytology has poor sensitivity** and is not established as an effective screening method.
- However, it has shown **some promise in research settings** for high-risk individuals, though it is not a standard or widely recommended screening approach.
- **Endometrial biopsy** remains the gold standard for diagnosis in symptomatic women, but routine screening of asymptomatic women is not recommended.
*USG in endometrial cancer*
- **Transvaginal ultrasonography (TVUS)** can effectively measure **endometrial thickness** and is valuable for evaluating postmenopausal bleeding.
- While not used for population-based screening of asymptomatic women, it aids in **risk stratification** and guiding further investigation like biopsy in symptomatic patients.
- When used appropriately in symptomatic women, TVUS is a useful diagnostic adjunct.
*Pap smear for cervical cancer*
- The **Pap smear** is a highly effective and widely adopted screening method for **cervical cancer**, detecting precancerous and cancerous changes in cervical cells.
- Its widespread use has **significantly reduced the incidence and mortality rates** of cervical cancer due to its ability to identify abnormalities early, allowing for timely intervention.
- This is the gold standard for cancer screening with proven mortality benefit.
Colorectal Cancer Indian Medical PG Question 3: Most common genetic alteration in colorectal carcinoma?
- A. BRAF mutation
- B. KRAS mutation
- C. p53 mutation
- D. APC mutation (Correct Answer)
Colorectal Cancer Explanation: ***APC mutation***
- **APC (adenomatous polyposis coli)** is a tumor suppressor gene, and its inactivation is the **earliest and most common genetic event** in colorectal carcinoma development [1].
- Mutations in APC lead to **uncontrolled cell proliferation** by disrupting the Wnt signaling pathway, which is crucial for colon crypt regeneration [1].
*BRAF mutation*
- **BRAF mutations** are associated with a subset of colorectal cancers, particularly those with **microsatellite instability (MSI)** and poor prognosis, but are not the most common overall [2].
- They occur in approximately **5-10% of colorectal cancers** and are primarily found in the sporadic, right-sided tumors.
*KRAS mutation*
- **KRAS mutations** are found in about 30-50% of colorectal cancers and are important in predicting resistance to anti-EGFR therapies [1].
- While common, they typically occur **later** in the progression from adenoma to carcinoma than APC mutations [1].
*p53 mutation*
- **p53 (TP53)** is a tumor suppressor gene, and mutations in p53 are very common in many cancers, including colorectal carcinoma.
- However, p53 mutations usually occur in the **later stages** of colorectal cancer development, often associated with the transition from adenoma to carcinoma and metastasis [2].
**References:**
[1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, p. 819.
[2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Alimentary System Disease, pp. 373-374.
Colorectal Cancer Indian Medical PG Question 4: What is the best marker to assess prognosis after surgery for colon carcinoma?
- A. CA 19-9
- B. CA-125
- C. Alpha fetoprotein
- D. CEA (Correct Answer)
Colorectal Cancer Explanation: ***CEA***
- Carcinoembryonic antigen (**CEA**) is a well-established tumor marker for monitoring colorectal cancer post-surgery and assessing prognosis [1].
- Elevated **CEA levels** after surgery may indicate recurrence or residual disease, making it valuable in follow-up care [1].
*CA 19-9*
- Primarily associated with **pancreatic** and **biliary tract cancers**, and not specific for colon carcinoma.
- While it may elevate in some gastrointestinal malignancies, it is not the best indicator for prognosis after colon cancer surgery.
*Alpha fetoprotein*
- Mostly used for monitoring **hepatocellular carcinoma** and germ cell tumors, not colorectal malignancies.
- Elevated levels are not typically correlated with prognosis in colon cancer patients.
*CA-125*
- Mainly utilized as a tumor marker for **ovarian cancer** and some other malignancies, not specifically for colon carcinoma.
- Its use in colorectal cancer prognosis is limited and lacks relevance in this context.
**References:**
[1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 253-254.
Colorectal Cancer Indian Medical PG Question 5: Best treatment strategy for carcinoma of the anal canal:
- A. Chemoradiation (Correct Answer)
- B. Radiation
- C. Surgery
- D. Chemotherapy
Colorectal Cancer Explanation: ***Chemoradiation***
- Carcinoma of the anal canal is primarily treated with **chemoradiation** (combinations of chemotherapy and radiation therapy) as the standard of care to achieve **organ preservation**.
- This combined approach improves local control and survival rates compared to either modality alone, making it the **primary curative strategy** for most localized anal canal cancers.
*Radiation*
- While radiation therapy is a crucial component of anal canal cancer treatment, using it alone (**monotherapy**) is generally less effective than chemoradiation.
- **Local recurrence rates** are higher with radiation alone compared to combined modality treatment.
*Surgery*
- Surgery, specifically **abdominoperineal resection (APR)**, is typically reserved for **recurrent disease** or cases where chemoradiation fails.
- Initial radical surgery for anal canal cancer leads to significant morbidity (e.g., permanent colostomy) and is generally avoided as a primary treatment due to the success of chemoradiation.
*Chemotherapy*
- Chemotherapy alone is **not curative** for localized anal canal carcinoma.
- It is primarily used in combination with radiation (chemoradiation) to sensitize the tumor to radiation and improve local control, or as treatment for **metastatic disease**.
Colorectal Cancer Indian Medical PG Question 6: All of the following are associated with increased risk of gastric adenocarcinoma except which of the following?
- A. Smoking
- B. Celiac disease (Correct Answer)
- C. H. pylori
- D. Dietary nitrosamines
Colorectal Cancer Explanation: ***Celiac disease***
- While celiac disease increases the risk of certain cancers like **T-cell lymphoma** (e.g., **enteropathy-associated T-cell lymphoma, EATL**) and **small intestinal adenocarcinoma**, it is not a significant risk factor for **gastric adenocarcinoma**.
- The primary site of neoplastic transformation in celiac disease is the **small intestine**, not the stomach.
*Smoking*
- **Smoking** is a well-established risk factor for various cancers, including gastric adenocarcinoma, with a dose-dependent relationship.
- It contributes to **chronic inflammation** and **mucosal damage** in the stomach, promoting oncogenesis.
*H. pylori*
- **_Helicobacter pylori_ infection** is a major causative agent for **gastric adenocarcinoma**, particularly the **intestinal type** [1].
- It induces chronic gastritis, leading to atrophy, intestinal metaplasia, and dysplasia, which are precursors to cancer [1], [2].
*Dietary nitrosamines*
- **Dietary nitrosamines**, commonly found in highly processed and preserved foods (smoked meats, pickled vegetables), are potent **carcinogens** [1].
- They are directly linked to an increased risk of **gastric adenocarcinoma**, especially in populations with high consumption of such foods [1].
Colorectal Cancer Indian Medical PG Question 7: What is the primary benefit of screening for diseases?
- A. Early detection of diseases (Correct Answer)
- B. Providing support for patients after diagnosis
- C. Identifying all potential cases of a disease
- D. Timely treatment of identified conditions
Colorectal Cancer Explanation: ***Early detection of diseases***
- This is the **primary benefit** and defining purpose of **screening programs** in public health.
- Screening identifies diseases in their **presymptomatic or early stage** when individuals are apparently healthy, allowing for intervention before clinical symptoms appear.
- According to epidemiological principles, the goal of screening is to detect disease **earlier than it would be found through routine clinical practice**.
- Early detection enables better prognosis through **lead time** and **length time bias** advantages.
*Timely treatment of identified conditions*
- While treatment is the **ultimate goal** of healthcare, it is not specific to screening—treatment occurs whether disease is found through screening or clinical presentation.
- Treatment is the **consequence** of early detection, not the primary benefit of the screening process itself.
- The unique value of screening lies in **detection**, not treatment per se.
*Providing support for patients after diagnosis*
- **Patient support** is an important aspect of healthcare but is not the purpose of screening programs.
- This is **post-diagnostic care**, which follows after the screening process has identified cases.
*Identifying all potential cases of a disease*
- **Screening tests** cannot identify all cases due to inherent limitations in **sensitivity** and **specificity**.
- Screening aims to identify a significant proportion of cases in a population, accepting that some will be missed (**false negatives**) and some healthy individuals may test positive (**false positives**).
Colorectal Cancer Indian Medical PG Question 8: 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
Colorectal Cancer 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.
Colorectal Cancer Indian Medical PG Question 9: Which is the most common site for colorectal cancer metastasis?
- A. Liver (Correct Answer)
- B. Brain
- C. Peritoneum
- D. Lungs
Colorectal Cancer Explanation: ***Liver***
- The liver is the **most common site** for colorectal cancer metastasis due to its direct vascular connection via the **portal venous system**.
- Blood from the colon and rectum drains into the **portal vein**, which then carries cancer cells directly to the liver.
*Brain*
- While brain metastases can occur, they are **relatively rare** and typically late manifestations in the course of colorectal cancer.
- The brain is **not the primary organ** for initial metastatic spread from colorectal cancer.
*Peritoneum*
- **Peritoneal carcinomatosis** is a significant mode of spread, especially in advanced colorectal cancer, but it is **less common** than liver metastasis.
- This type of spread involves the **lining of the abdominal cavity**, often leading to ascites and bowel obstruction.
*Lungs*
- **Pulmonary metastasis** is the **second most common** site for colorectal cancer after the liver.
- Cancer cells reaching the lungs usually do so via the **systemic circulation** after passing through or bypassing the liver.
Colorectal Cancer Indian Medical PG Question 10: Colonoscopy is not indicated in which of the following conditions?
- A. Familial Adenomatous Polyposis
- B. Multiple Endocrine Neoplasia type 2B (Correct Answer)
- C. Hereditary Nonpolyposis Colorectal Cancer
- D. Peutz-Jeghers Syndrome
Colorectal Cancer Explanation: ***Multiple Endocrine Neoplasia type 2B***
- **MEN 2B** is characterized by **medullary thyroid carcinoma**, **pheochromocytoma**, and specific features such as **mucosal neuromas** and a marfanoid habitus, but it does **not involve colonic polyps or an increased risk of colorectal cancer** that would necessitate colonoscopy.
- While gastrointestinal manifestations like ganglioneuromatosis may be present, **routine colonoscopy screening** is not indicated in this syndrome as there is no increased colorectal cancer risk.
*Familial Adenomatous Polyposis*
- **FAP** is an autosomal dominant disorder characterized by the development of hundreds to thousands of **colorectal adenomatous polyps**, which have an almost 100% risk of progressing to **colorectal cancer** if untreated.
- **Regular colonoscopic surveillance** and eventual colectomy are essential for managing this condition due to the high malignancy risk.
*Hereditary Nonpolyposis Colorectal Cancer*
- Also known as **Lynch syndrome**, HNPCC is characterized by an increased risk of **colorectal cancer** and other extra-colonic cancers (e.g., endometrial, ovarian) due to germline mutations in **mismatch repair genes**.
- **Colonoscopy is crucial** for early detection and prevention of colorectal cancer in affected individuals, typically starting at age 20-25 years or 2-5 years before the youngest family member was diagnosed.
*Peutz-Jeghers Syndrome*
- **Peutz-Jeghers Syndrome** is an autosomal dominant condition characterized by **hamartomatous polyps** throughout the gastrointestinal tract and mucocutaneous pigmentation (melanotic macules on lips, oral mucosa, and digits).
- These polyps have **malignant potential** with increased risk of gastrointestinal and extra-intestinal cancers (breast, ovarian, pancreatic).
- **Regular colonoscopic surveillance** is recommended starting from late teens or early 20s for polyp detection and removal.
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