Neoplasia Practice Questions

Q: An example of a tumor suppressor gene is

Rb. The correct answer is **D. Rb (Retinoblastoma gene)**. **1. Why Rb is the Correct Answer:** Tumor suppressor genes (TSGs) act as the "brakes" of the cell cycle, preventing uncontrolled cell proliferation [1]. The **Rb gene**, located on chromosome **13q14**, is the classic example of a TSG. It encodes the pRb protein, which regulates the **G1 to S phase transition** [1]. In its hypophosphorylated state, pRb binds to the E2F transcription factor, preventing the cell from entering the S phase. Loss of both alleles (Knudson’s "Two-Hit Hypothesis") leads to unregulated cell growth, resulting in tumors like Retinoblastoma and Osteosarcoma. **2. Why Other Options are Incorrect:** * **A. Myc:** This is a **proto-oncogene** (specifically a nuclear transcription factor). Overexpression of c-Myc is classically associated with Burkitt Lymphoma [t(8;14)]. * **B. Fos:** This is also a **proto-oncogene** that codes for nuclear transcription factors involved in cell proliferation and differentiation. * **C. Ras:** This is the most common **proto-oncogene** in human tumors [1]. It encodes a GTP-binding protein involved in signal transduction. Mutations in Ras (H-ras, K-ras, N-ras) lead to constitutive activation of the MAPK pathway [1]. **3. High-Yield Clinical Pearls for NEET-PG:** * **TP53:** The "Guardian of the Genome," located on chromosome 17p. It is the most commonly mutated gene in human cancers. * **Two-Hit Hypothesis:** Proposed by Knudson specifically for the Rb gene. * **Li-Fraumeni Syndrome:** Caused by a germline mutation in TP53. * **VHL Gene:** A tumor suppressor gene on chromosome 3, associated with Von Hippel-Lindau disease (Renal cell carcinoma, Hemangioblastomas).

Q: CA 125 is used for what purpose?

Follow-up of ovarian cancer. **CA 125 (Cancer Antigen 125)** is a high-molecular-weight glycoprotein primarily used as a tumor marker for **non-mucinous epithelial ovarian tumors**. [1] 1. **Why Option A is Correct:** The primary clinical utility of CA 125 lies in **monitoring the response to therapy** and **detecting the recurrence** (follow-up) of ovarian cancer. [1] A significant drop in levels post-surgery or chemotherapy indicates a good response, while a subsequent rise often precedes clinical or radiological evidence of recurrence by months. 2. **Why Other Options are Incorrect:** * **Option D (Diagnosis of Ovarian Cancer):** CA 125 is **not** used for primary diagnosis or screening in the general population because it lacks specificity. [1] It can be elevated in various non-malignant conditions such as endometriosis, pelvic inflammatory disease (PID), pregnancy, and menstruation. * **Options B & C (Pancreatic and Stomach Cancer):** While CA 125 can be elevated in various intra-abdominal malignancies due to peritoneal irritation, it is not the marker of choice. **CA 19-9** is the specific marker for pancreatic cancer, and **CEA** is more commonly associated with gastric malignancies. [1] **High-Yield Clinical Pearls for NEET-PG:** * **Most sensitive marker for Ovarian Cancer:** CA 125 (specifically for Serous Cystadenocarcinoma). * **Marker for Mucinous Ovarian Tumors:** CEA (CA 125 is often normal). * **Marker for Yolk Sac Tumor:** Alpha-fetoprotein (AFP). * **Marker for Dysgerminoma:** LDH. * **Marker for Granulosa Cell Tumor:** Inhibin. * **Meigs Syndrome:** Characterized by the triad of ovarian fibroma, ascites, and pleural effusion; it can cause a "false positive" elevation of CA 125. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 344-346.

Q: All of the following are carcinogenic except?

Campylobacter. **Explanation:** The correct answer is **Campylobacter**. While several infectious agents are classified as Group 1 carcinogens by the IARC, *Campylobacter jejuni* is primarily associated with acute gastroenteritis and post-infectious Guillain-Barré syndrome, but it has no proven direct oncogenic potential. **Why the other options are wrong (Carcinogenic potential):** * **H. pylori:** This is the most common bacterial cause of cancer [1]. It is strongly associated with **Gastric Adenocarcinoma** (via chronic atrophic gastritis) and **MALToma** (Mucosa-Associated Lymphoid Tissue lymphoma) [1]. * **Hepatitis B virus (HBV):** A DNA virus that integrates into the host genome, leading to chronic inflammation and cirrhosis. It is a major risk factor for **Hepatocellular Carcinoma (HCC)**. * **Epstein-Barr virus (EBV):** Known as human herpesvirus 4, it is associated with several malignancies, including **Burkitt Lymphoma**, **Nasopharyngeal Carcinoma**, Hodgkin Lymphoma, and CNS lymphoma in HIV patients. **High-Yield Clinical Pearls for NEET-PG:** 1. **Bacterial Carcinogens:** Apart from *H. pylori*, *Salmonella typhi* (gallbladder cancer) and *Streptococcus bovis* (colorectal cancer) are high-yield associations. 2. **Parasitic Carcinogens:** *Schistosoma haematobium* (Squamous cell carcinoma of the bladder) and *Clonorchis sinensis* (Cholangiocarcinoma). 3. **Viral Carcinogens:** Human Papillomavirus (HPV 16, 18) for cervical/anal cancer and HHV-8 for Kaposi Sarcoma. 4. **Mnemonic:** Remember that *Campylobacter* causes "Cramps," not "Cancer."

Question 1

An example of a tumor suppressor gene is

Accepted Answer

Rb

Answer

Myc

Answer

Fos

Answer

Ras

Question 2

CA 125 is used for what purpose?

Accepted Answer

Follow-up of ovarian cancer

Answer

Diagnosis of pancreatic cancer

Answer

Diagnosis of stomach cancer

Answer

Diagnosis of ovarian cancer

Question 3

Which of the following conditions is NOT associated with exposure to coal tar?

Accepted Answer

Leukemia

Answer

Bladder cancer

Answer

Skin cancer

Answer

Lung cancer

Question 4

Which of the following is NOT one of the four key cell cycle regulators that are dysregulated in a variety of human cancers?

Accepted Answer

P21

Answer

P16/INK4a

Answer

Cyclin D

Answer

RB

Question 5

A child is diagnosed with neurofibromatosis type 1, characterized by cafe-au-lait spots and Lisch nodules. The protein mutated in this disorder normally performs which of the following functions?

Accepted Answer

Activates the GTPase activity of Ras

Answer

Cleaves cellular proteins during apoptosis

Answer

Functions as a cell cycle checkpoint regulator

Answer

Promotes angiogenesis

Question 6

All of the following statements are true regarding retinoblastoma, except:

Accepted Answer

The Rb gene is on chromosome 13q14.

Answer

Rb genes play a major role in cell cycle regulation.

Answer

Requires deletion of both Rb genes.

Answer

Familial variant is autosomal dominant in inheritance.

Question 7

Which of the following is true about proto-oncogenes?

Accepted Answer

Important for normal cell growth

Answer

Involved in oncogenesis

Answer

C-myc overexpression causes lymphoma

Answer

Mutation causes Retinoblastoma

Question 8

All of the following are carcinogenic except?

Accepted Answer

Campylobacter

Answer

H. pylori

Answer

Hepatitis B virus

Answer

Epstein-Barr virus

Question 9

A clinical study involves patients diagnosed with carcinoma whose tumor stage is T4N1M1. The patients' survival rate 5 years from the time of diagnosis is less than 50%, regardless of therapy. Which of the following clinical findings is most likely to be characteristic of this group of patients?

Accepted Answer

Cachexia

Answer

Cardiac murmur

Answer

Icterus

Answer

Loss of sensation

Question 10

Which of the following changes in the C-MYC oncogene may be associated with colonic malignancy?

Accepted Answer

Amplification

Answer

Point mutation

Answer

Rearrangement

Answer

Deletion

Neoplasia — MCQs

Neoplasia — MCQs

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