Neoplasia Practice Questions

Q: BRCA1 gene mutation is not associated with which of the following cancers?

Endometrial carcinoma. **Explanation:** The BRCA1 (Breast Cancer 1) gene is a tumor suppressor gene located on **chromosome 17q21**. It plays a critical role in DNA repair via homologous recombination. Mutations in this gene significantly increase the lifetime risk of specific cancers, primarily those of the breast and the female reproductive tract (ovary and fallopian tube). * **Why Endometrial Carcinoma (Option C) is the correct answer:** While some recent studies suggest a potential minor increase in the risk of rare, aggressive serous-like endometrial cancers in BRCA1 carriers, it is **not** traditionally considered part of the core BRCA1 clinical syndrome. Standard screening and prophylactic guidelines for BRCA1 mutation carriers focus on breast and ovarian/tubal health, not the endometrium. * **Why other options are incorrect:** * **Breast Carcinoma (Option B):** This is the most common association. BRCA1 mutations carry a lifetime risk of breast cancer up to 65–80%. * **Ovarian Carcinoma (Option A):** BRCA1 is strongly associated with epithelial ovarian cancer (specifically high-grade serous carcinoma), with a lifetime risk of approximately 40%. * **Fallopian Tube Cancer (Option D):** Modern pathology suggests that many "ovarian" cancers actually originate in the fimbrial end of the fallopian tube (STIC lesions). BRCA1 is a major risk factor for primary fallopian tube carcinoma. **High-Yield Clinical Pearls for NEET-PG:** 1. **Chromosome Location:** BRCA1 is on **17q**, while BRCA2 is on **13q**. 2. **Associated Cancers (BRCA1):** Breast (often Triple Negative), Ovary, Fallopian tube, and Prostate (lower risk than BRCA2). 3. **Associated Cancers (BRCA2):** Breast (including male breast cancer), Ovary, **Pancreas**, and Prostate. 4. **Prophylaxis:** Risk-reducing salpingo-oophorectomy (RRSO) is recommended for BRCA1 carriers between ages 35–40.

Q: Which one of the following tumors does not commonly cause bony metastasis?

Gastric carcinoma. The most common sites for bony metastasis are the **vertebrae, pelvis, femur, and skull**. This occurs primarily via the **Batson’s venous plexus**, a valveless system that connects the deep pelvic veins and thoracic veins to the internal vertebral venous plexus. **Why Gastric Carcinoma is the Correct Answer:** While gastric carcinoma can spread to the liver (most common) and peritoneum (Krukenberg tumor), it **rarely** metastasizes to the bone. In contrast, cancers of the breast, prostate, lung, kidney, and thyroid are considered "osteophilic" (bone-seeking) and account for the vast majority of skeletal metastases [2]. **Analysis of Incorrect Options:** * **Breast Carcinoma:** The most common cause of bony metastasis in females. It typically produces **mixed** (osteolytic and osteoblastic) lesions. * **Renal Cell Carcinoma (RCC):** Frequently metastasizes to the bone, characteristically causing **purely osteolytic**, expansile, and highly vascular "pulsatile" metastases. * **Thyroid Carcinoma:** Particularly the follicular variant, it is well-known for spreading to the bone (often the skull or ribs) via the hematogenous route, producing osteolytic lesions [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for Bony Metastasis:** "**P**hiladelphia **B**ullets **L**ead **T**o **K**illing" (**P**rostate, **B**reast, **L**ung, **T**hyroid, **K**idney). * **Osteoblastic (Sclerotic) Lesions:** Most common in **Prostate Cancer**. * **Osteolytic Lesions:** Most common in **Lung, Thyroid, and RCC**. * **Batson’s Plexus:** Explains why pelvic/abdominal cancers can spread to the spine without involving the lungs (bypassing the caval system).

Q: What is the most common abnormality of a proto-oncogene in human tumors?

Point mutation in RAS family gene. ### Explanation The correct answer is **Point mutation in RAS family gene**. **1. Why RAS is correct:** The **RAS gene family** (HRAS, KRAS, NRAS) represents the most frequently mutated group of **proto-oncogenes** in human cancers. Approximately 30% of all human tumors harbor a RAS mutation. The underlying mechanism is a **single nucleotide point mutation**, most commonly at codons 12, 13, or 61. This mutation interferes with the GTPase activity of the RAS protein, trapping it in a "constitutively active" GTP-bound state, leading to continuous pro-growth signaling to the nucleus [2]. **2. Analysis of Incorrect Options:** * **p53 point mutations:** While *TP53* is the most commonly mutated gene in human cancer overall, it is a **tumor suppressor gene**, not a proto-oncogene [2]. The question specifically asks for a proto-oncogene. * **Point mutation in C-kit:** While mutations in *c-KIT* are characteristic of Gastrointestinal Stromal Tumors (GIST) and mastocytosis, they are not as ubiquitous across all human cancers as RAS mutations. * **Overexpression of RET:** *RET* mutations/rearrangements are specific to conditions like MEN 2A/2B and Medullary Thyroid Carcinoma [1]. It is a tissue-specific abnormality rather than the most common global proto-oncogene defect. **3. High-Yield Clinical Pearls for NEET-PG:** * **KRAS:** Most common RAS mutation; associated with **Pancreatic adenocarcinoma** (90%+) and **Colon cancer**. * **NRAS:** Associated with **Melanomas** and Hematologic malignancies (AML). * **HRAS:** Associated with **Bladder tumors**. * **Mechanism:** RAS mutations result in the failure of **GTP hydrolysis** (loss of GAP function), keeping the molecular switch "ON." **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, p. 292. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 291-292.

Question 1

BRCA1 gene mutation is not associated with which of the following cancers?

Accepted Answer

Endometrial carcinoma

Answer

Ovarian carcinoma

Answer

Breast carcinoma

Answer

Fallopian tube cancer

Question 2

Benzopyrene is changed to a carcinogen in animals due to all of the following mechanisms EXCEPT:

Accepted Answer

Cytochrome C activation

Answer

Epoxide formation

Answer

p53 activation

Answer

Induction of metabolism by cytochrome P450

Question 3

Invasive carcinoma differs from carcinoma in situ by:

Accepted Answer

Breached basement membrane

Answer

Abnormal nuclear morphology

Answer

Pleomorphism

Answer

Mitoses

Question 4

Which of the following is not a benign neoplasm?

Accepted Answer

Seminoma

Answer

Chondroma

Answer

Leiomyoma

Answer

Papilloma

Question 5

Cancer cells primarily derive energy from which metabolic process?

Accepted Answer

Glycolysis

Answer

Oxidative metabolism

Answer

Increased mitochondria

Answer

None of the above

Question 6

Which one of the following tumors does not commonly cause bony metastasis?

Accepted Answer

Gastric carcinoma

Answer

Renal cell carcinoma

Answer

Thyroid carcinoma

Answer

Breast carcinoma

Question 7

Cowden syndrome is commonly associated with which of the following?

Accepted Answer

Hamartoma

Answer

Renal cell carcinoma

Answer

Thymic carcinoid

Answer

Cerebellar haemangioblastoma

Question 8

Which of the following cancers is least associated with genetic and familial causes?

Accepted Answer

Lung

Answer

Ovarian

Answer

Prostate

Answer

Breast

Question 9

A 63-year-old woman discovers a lump in her right breast. Mammography confirms the presence of a suspicious mass, and a needle core biopsy reveals that the mass is cancerous with amplification of the Her-2/neu oncogene. What kind of protein is the gene product of Her-2/neu?

Accepted Answer

Receptor tyrosine kinase

Answer

GTPase

Answer

GTPase-activating protein

Answer

Nuclear transcription factor

Question 10

What is the most common abnormality of a proto-oncogene in human tumors?

Accepted Answer

Point mutation in RAS family gene

Answer

p53 point mutations

Answer

Point mutation in C-kit gene

Answer

Overexpression of RET proto-oncogene

Neoplasia — MCQs

Neoplasia — MCQs

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