Neoplasia Practice Questions

Q: Which of the following conditions is inherited in an autosomal dominant pattern?

Retinoblastoma. **Explanation:** The correct answer is **Retinoblastoma (Option A)**. Retinoblastoma is the most common primary intraocular malignancy of childhood. While 60% of cases are sporadic and unilateral, 40% are hereditary. Hereditary retinoblastoma follows an **Autosomal Dominant** inheritance pattern with high penetrance (90%). It is caused by a mutation in the **RB1 gene** located on chromosome **13q14**. According to **Knudson’s Two-Hit Hypothesis**, in hereditary cases, the first mutation (hit) is germline (inherited), and the second is somatic. This explains why hereditary cases are often bilateral, multifocal, and present at an earlier age. **Why the other options are incorrect:** * **Ataxia Telangiectasia (Option B):** This is an **Autosomal Recessive** multisystem disorder characterized by cerebellar ataxia, oculocutaneous telangiectasia, and immunodeficiency. It involves a defect in the ATM gene (DNA repair). * **Bloom’s Syndrome (Option C):** This is an **Autosomal Recessive** disorder characterized by short stature, photosensitivity, and genomic instability due to mutations in the BLM gene. * **Xeroderma Pigmentosa (Option D):** This is an **Autosomal Recessive** condition caused by a defect in nucleotide excision repair, leading to extreme sensitivity to UV light and a high risk of skin malignancies. **High-Yield Clinical Pearls for NEET-PG:** * **Most common presenting sign:** Leukocoria (White pupillary reflex). * **Second most common sign:** Strabismus. * **Pathognomonic Histology:** Flexner-Wintersteiner rosettes. * **Calcification:** Present in 90% of cases (visible on CT/Ultrasound B-scan); a key diagnostic feature. * **Trilateral Retinoblastoma:** Bilateral retinoblastoma associated with a pinealoblastoma.

Q: Which of the following is essential for tumor metastasis?

Angiogenesis. **Explanation:** **1. Why Angiogenesis is Correct:** For a tumor to grow beyond 1–2 mm in diameter and eventually metastasize, it requires a dedicated blood supply. **Angiogenesis** is the process of forming new blood vessels from pre-existing ones. This is essential for metastasis because: * **Nutrient Supply:** It provides the oxygen and nutrients necessary for the primary tumor to expand. * **Route of Exit:** New vessels are often "leaky" and have weak basement membranes, allowing tumor cells to enter the systemic circulation (**intravasation**) and travel to distant organs. * **Growth at Distant Sites:** Once tumor cells lodge in a new organ, they must trigger angiogenesis again to grow into a clinically detectable secondary mass [1]. **2. Why Other Options are Incorrect:** * **B. Tumorogenesis:** This refers to the initial formation or "birth" of a tumor (transformation of normal cells to neoplastic cells). While it is the first step in cancer, it does not specifically describe the mechanism of spread (metastasis). * **C. Apoptosis:** This is programmed cell death. Metastatic cells must actually **evade** apoptosis to survive in the bloodstream and colonize new tissues. Increased apoptosis would hinder, not help, metastasis. * **D. Inhibition of Tyrosine Kinase:** Tyrosine kinases are enzymes that signal cells to grow. Inhibiting them (e.g., using Imatinib) is a therapeutic strategy to **stop** cancer progression. **3. Clinical Pearls for NEET-PG:** * **Key Mediator:** **VEGF** (Vascular Endothelial Growth Factor) is the most potent stimulator of angiogenesis. * **Therapeutic Link:** **Bevacizumab** is a monoclonal antibody against VEGF used to inhibit angiogenesis in various cancers. * **HIF-1α:** Hypoxia-inducible factor-1α is the transcription factor that upregulates VEGF in response to low oxygen levels within a tumor.

Q: Smoking is a risk factor for all carcinomas except which of the following?

Thyroid. The correct answer is **Thyroid**. While smoking is a notorious risk factor for a vast array of malignancies, it has a paradoxical relationship with thyroid cancer. **1. Why Thyroid is the Correct Answer:** Epidemiological studies consistently show that smoking is **not** a risk factor for thyroid carcinoma [1]. In fact, smoking is associated with a **decreased risk** of developing papillary thyroid cancer [1]. This is hypothesized to be due to the anti-estrogenic effects of smoking and a reduction in Body Mass Index (BMI), as both high estrogen levels and obesity are known risk factors for thyroid malignancies. Additionally, smoking may lower Thyroid Stimulating Hormone (TSH) levels, reducing the trophic stimulus to thyroid follicular cells [2]. **2. Why the Other Options are Incorrect:** * **Oral Carcinoma:** Smoking introduces potent carcinogens (like polycyclic aromatic hydrocarbons) directly to the oral mucosa, acting synergistically with alcohol to cause Squamous Cell Carcinoma (SCC). * **Bronchial Carcinoma:** Smoking is the primary cause of lung cancer (Small cell and SCC). Carcinogens cause DNA adducts and mutations in the *TP53* and *KRAS* genes. * **Bladder Carcinoma:** This is a high-yield fact. Carcinogens (like beta-naphthylamine) are absorbed into the bloodstream and excreted in the urine, leading to prolonged contact with the urothelium, causing Transitional Cell Carcinoma (TCC). **3. NEET-PG Clinical Pearls:** * **Paradoxical Benefit:** Smoking is also associated with a decreased risk of **Endometrial Cancer** (due to anti-estrogenic effects) and **Ulcerative Colitis**. * **Bladder Cancer:** Smoking is the **most common** risk factor for bladder cancer in the general population. * **Pancreatic Cancer:** Smoking is one of the few modifiable risk factors for pancreatic adenocarcinoma.

Q: Loss of heterozygosity is associated with which of the following conditions?

Retinoblastoma. **Explanation:** **Loss of Heterozygosity (LOH)** is a critical genetic event where a cell loses one of its two functional alleles at a specific locus. This concept is central to the **Knudson’s "Two-Hit" Hypothesis** of tumor suppressor genes [1]. **Why Retinoblastoma is correct:** Retinoblastoma is the classic example of LOH involving the **RB1 gene** on chromosome **13q14** [2]. In the hereditary form, a child inherits one defective allele (the first "hit"). A subsequent somatic mutation or chromosomal event (like mitotic recombination or nondisjunction) leads to the loss of the remaining functional wild-type allele (the second "hit") [1]. This transition from a heterozygous state (+/-) to a homozygous/hemizygous mutant state (-/-) is termed Loss of Heterozygosity, leading to uncontrolled cell proliferation [2]. **Why other options are incorrect:** * **Acute Myeloid Leukemia (AML) & Acute Lymphoblastic Leukemia (ALL):** While these involve complex genetic mutations and deletions, they are primarily characterized by chromosomal translocations (e.g., t(8;21) in AML) or numerical abnormalities rather than the classic LOH model seen in solid tumor suppressor syndromes. * **Acute Promyelocytic Leukemia (APL):** This is specifically characterized by the **t(15;17)** translocation, which creates the *PML-RARA* fusion protein. It is a gain-of-function/dominant-negative mutation rather than a loss of heterozygosity of a tumor suppressor. **High-Yield Facts for NEET-PG:** * **RB1 Gene:** Located on **13q14**; its protein (pRb) inhibits the **E2F transcription factor**, arresting the cell cycle in the **G1 phase**. * **Other LOH Examples:** Li-Fraumeni Syndrome (TP53), Familial Adenomatous Polyposis (APC), and Lynch Syndrome (Mismatch repair genes). * **Microscopic Hallmark:** Flexner-Wintersteiner rosettes are characteristic of Retinoblastoma [2].

Question 1

Which of the following conditions is inherited in an autosomal dominant pattern?

Accepted Answer

Retinoblastoma

Answer

Ataxia telangiectasia

Answer

Bloom's syndrome

Answer

Xeroderma pigmentosa

Question 2

Which of the following is known as the guardian of the genes?

Accepted Answer

p53

Answer

Rb

Answer

p16

Answer

p73

Question 3

Which of the following is essential for tumor metastasis?

Accepted Answer

Angiogenesis

Answer

Tumorogenesis

Answer

Apoptosis

Answer

Inhibition of tyrosine kinase activity

Question 4

Polycythemia is associated with all of the following cancers except?

Accepted Answer

Prostate cancer

Answer

Stomach cancer

Answer

Liver cancer

Answer

Renal cell cancer

Question 5

Smoking is a risk factor for all carcinomas except which of the following?

Accepted Answer

Thyroid

Answer

Oral

Answer

Bronchial

Answer

Bladder

Question 6

Loss of heterozygosity is associated with which of the following conditions?

Accepted Answer

Retinoblastoma

Answer

Acute myeloid leukemia

Answer

Acute lymphoblastic leukemia

Answer

Acute promyelocytic leukemia

Question 7

Which enzymatic mutation is responsible for immortality of cancer cells?

Accepted Answer

Telomerase

Answer

DNA reverse transcriptase

Answer

RNA polymerase

Answer

DNA polymerase

Question 8

Cancer cachexia is due to which of the following cytokines?

Accepted Answer

TNF-α

Answer

IL-5

Answer

IL-8

Answer

Phospholipase A2

Question 9

Which of the following statements is false regarding tumor hypoxia?

Accepted Answer

Oxygen does not affect the radiosensitivity of tumors.

Answer

Hypoxia in tumors can result from two different mechanisms: chronic hypoxia and acute hypoxia.

Answer

Acute hypoxia is caused by a temporary closing of a blood vessel in the tumor.

Answer

Chronic hypoxia is caused by the limited diffusion distance of oxygen through tissue that is respiring.

Question 10

A 60-year-old male presents with hematuria and weight loss. Cystoscopy biopsy of a superficial lesion in the bladder shows hyperchromatic nuclei, an increased nuclear-to-cytoplasmic ratio. The lesion involves the full thickness of the epithelium but does not invade the basement membrane. What is the diagnosis?

Accepted Answer

Bladder carcinoma in situ

Answer

Dysplasia

Answer

Metaplasia

Answer

Micro invasion

Neoplasia — MCQs

Neoplasia — MCQs

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