Oncology Flashcards
Which of the following best defines breast cancer?
A. A benign proliferation of stromal cells in the breast
B. A malignant proliferation of epithelial cells originating in the ducts or lobules
C. A malignant proliferation of lymphatic cells within the breast
D. A benign hyperplasia of the breast’s adipose tissue
E. A non-invasive proliferation of epithelial cells confined to the basement membrane
Answer: B
Explanation: Breast cancer is defined as a malignant proliferation of epithelial cells that originate in the ducts or lobules of the breast. This distinguishes it from benign or purely in situ lesions.
What is one of the primary reasons for the decline in breast cancer mortality over the past three decades?
A. A significant reduction in breast cancer incidence
B. The universal use of prophylactic mastectomy
C. Early detection through screening and improved treatment modalities
D. Complete elimination of exogenous estrogen exposure
E. Advances in gene therapy
Answer: C
Explanation: The decline in mortality is largely attributed to early detection through screening (e.g., mammography) and improved treatment strategies, including targeted therapies and adjuvant systemic treatments.
Which key molecular marker is most critical for determining the use of endocrine (hormonal) therapy in breast cancer?
A. HER2 overexpression
B. BRCA1 mutation
C. Estrogen receptor (ER) expression
D. PIK3CA mutation
E. mTOR activation
Answer:
C. Estrogen receptor (ER) expression
Explanation:
Estrogen receptor (ER) expression is the most critical molecular marker for determining the use of endocrine (hormonal) therapy in breast cancer. ER-positive tumors respond to hormonal therapies such as selective estrogen receptor modulators (e.g., tamoxifen) and aromatase inhibitors. While HER2 overexpression (A) guides the use of HER2-targeted therapies, BRCA1 mutations (B) influence risk and treatment decisions but are not directly linked to endocrine therapy. PIK3CA mutations (D) and mTOR activation (E) are involved in targeted therapy decisions but are not primary determinants for endocrine therapy use.
Which of the following best defines breast cancer?
A. A benign proliferation of stromal cells in the breast
B. A malignant proliferation of epithelial cells originating in the ducts or lobules
C. A malignant proliferation of lymphatic cells within the breast
D. A benign hyperplasia of the breast’s adipose tissue
E. A non-invasive proliferation of epithelial cells confined to the basement membrane
Answer: B
Explanation: Breast cancer is defined as a malignant proliferation of epithelial cells that originate in the ducts or lobules of the breast. This distinguishes it from benign or purely in situ lesions.
Which targeted therapeutic approach is specifically employed in triple-negative breast cancer (TNBC) based on recent advances in molecular oncology?
A. CDK4/6 inhibitors
B. Anti-PD-1/PD-L1 immune checkpoint inhibitors
C. HER2-targeted therapy
D. Aromatase inhibitors
E. mTOR inhibitors
Answer:
B. Anti-PD-1/PD-L1 immune checkpoint inhibitors
Explanation:
Triple-negative breast cancer (TNBC) lacks expression of estrogen receptor (ER), progesterone receptor (PR), and HER2, making it unresponsive to endocrine or HER2-targeted therapies. Recent advances in molecular oncology have led to the use of immune checkpoint inhibitors (e.g., anti-PD-1/PD-L1 therapy) in TNBC, particularly in cases with high PD-L1 expression.
• CDK4/6 inhibitors (A) are used in ER-positive, HER2-negative breast cancer.
• HER2-targeted therapy (C) is for HER2-positive breast cancer.
• Aromatase inhibitors (D) are used in hormone receptor-positive breast cancer.
• mTOR inhibitors (E) are used for hormone receptor-positive, HER2-negative breast cancer resistant to endocrine therapy.
Regarding the incidence of breast cancer, which statement best describes the age distribution?
A. Breast cancer predominantly occurs in women under 40 years old.
B. Over 75% of breast cancer cases occur in women over 50 years old, though it can also occur in younger women.
C. Breast cancer incidence is uniform across all age groups.
D. The risk of breast cancer decreases steadily after age 50.
E. Breast cancer is extremely rare in women over 70.
Answer:
B. Over 75% of breast cancer cases occur in women over 50 years old, though it can also occur in younger women.
Explanation:
Breast cancer is most commonly diagnosed in older women, with over 75% of cases occurring in those over 50 years old. However, it can also affect younger women, including those in their 40s, 30s, and rarely even younger.
• (A) Incorrect: While breast cancer can occur in younger women, it is much more common in those over 50.
• (C) Incorrect: The incidence is not uniform; it increases with age.
• (D) Incorrect: The risk of breast cancer does not steadily decrease after 50; rather, it continues to rise with age.
• (E) Incorrect: Breast cancer is not extremely rare in women over 70—while the incidence may stabilize, older women remain at significant risk.
A 65-year-old male smoker presents with a persistent cough, hemoptysis, and unintentional weight loss. Chest X-ray shows a central lung mass. Which of the following is the most likely diagnosis?
A) Small-cell lung cancer (SCLC)
B) Adenocarcinoma
C) Large-cell carcinoma
D) Mesothelioma
Answer: A) Small-cell lung cancer (SCLC)
(Central location, aggressive course, and smoking history suggest SCLC.)
A 55-year-old woman, a lifelong non-smoker, presents with progressive shortness of breath. Imaging shows a peripheral lung nodule. A biopsy reveals TTF-1 positive and Napsin-A positive cells. What is the most likely diagnosis?
A) Squamous cell carcinoma
B) Adenocarcinoma
C) Small-cell lung cancer
D) Mesothelioma
Answer: B) Adenocarcinoma
(TTF-1 and Napsin-A positivity suggest adenocarcinoma, the most common lung cancer in non-smokers.)
A 67-year-old retired construction worker with a history of asbestos exposure presents with chest pain and pleural effusion. Imaging shows pleural thickening. Which immunohistochemical marker is most suggestive of the suspected diagnosis?
A) TTF-1
B) CK7
C) Calretinin
D) Chromogranin
Answer: C) Calretinin
(Strong marker for mesothelioma, which is associated with asbestos exposure.)
A 60-year-old male smoker presents with hoarseness and a right-sided lung mass compressing the recurrent laryngeal nerve. What is the most likely lung cancer type?
A) Squamous cell carcinoma
B) Small-cell lung cancer
C) Adenocarcinoma
D) Large-cell carcinoma
Answer: A) Squamous cell carcinoma
(Tends to be centrally located and can compress the recurrent laryngeal nerve.)
A 58-year-old woman with chronic cough and weight loss has a biopsy showing keratinization and intercellular bridges. Which marker would be most helpful to confirm the diagnosis?
A) TTF-1
B) Napsin-A
C) p40
D) CD56
Answer: C) p40
Explanation: The biopsy findings of keratinization and intercellular bridges strongly suggest squamous cell carcinoma (SCC) of the lung. p40 is the most specific immunohistochemical marker for SCC, making it the best choice for confirming the diagnosis.
• TTF-1 (A) and Napsin-A (B) are markers for adenocarcinoma.
• CD56 (D) is a neuroendocrine marker, seen in small-cell lung cancer (SCLC) and other neuroendocrine tumors.
A 70-year-old man with a history of smoking presents with hyponatremia (Na+ = 122 mEq/L), confusion, and lethargy. Imaging shows a central lung mass. Which mechanism best explains his findings?
A) ACTH secretion
B) Parathyroid hormone-related protein (PTHrP)
C) SIADH (Syndrome of inappropriate ADH secretion)
D) Hypercoagulability
Answer: C) SIADH (Syndrome of Inappropriate ADH Secretion)
Explanation:
The patient is a heavy smoker with a central lung mass and hyponatremia (Na+ = 122 mEq/L), suggesting small-cell lung cancer (SCLC). SCLC is commonly associated with paraneoplastic SIADH, which leads to excess ADH secretion, causing hyponatremia, confusion, and lethargy due to water retention and dilutional effects.
(A) ACTH secretion → Seen in SCLC but causes Cushing’s syndrome (hypertension, hyperglycemia, and hypokalemia), not hyponatremia.
(B) PTHrP → Seen in squamous cell carcinoma, causing hypercalcemia, not hyponatremia.
(D) Hypercoagulability → Lung cancer can cause a hypercoagulable state (e.g., Trousseau’s syndrome), but this does not explain hyponatremia.
A 59-year-old woman with lung cancer develops facial swelling and dilated neck veins. What is the most likely underlying cause?
A) Pericardial effusion
B) Tumor invasion of the brachial plexus
C) Superior vena cava (SVC) syndrome
D) Pulmonary embolism
Answer: C) Superior vena cava (SVC) syndrome
Explanation:
The patient’s facial swelling and dilated neck veins suggest SVC syndrome, which occurs due to obstruction of the superior vena cava by a lung tumor, most commonly small-cell lung cancer (SCLC). Compression of the SVC leads to impaired venous return from the head, neck, and upper extremities, causing:
• Facial swelling and plethora
• Dilated neck and chest veins
• Dyspnea (due to upper airway edema)
Why not the other options?
(A) Pericardial effusion → Can cause cardiac tamponade, leading to hypotension and distant heart sounds, but does not directly cause facial swelling and neck vein distension.
(B) Tumor invasion of the brachial plexus → Can cause shoulder pain and arm weakness (Pancoast tumor) but not venous congestion.
(D) Pulmonary embolism → Can cause sudden dyspnea, chest pain, and tachycardia, but does not lead to facial swelling or dilated neck veins.
A 62-year-old man presents with bone pain and a lung mass. His calcium level is 13.5 mg/dL. Which lung cancer type is most associated with his condition?
A) Adenocarcinoma
B) Squamous cell carcinoma
C) Small-cell lung cancer
D) Large-cell carcinoma
Answer: B) Squamous cell carcinoma
Explanation:
This patient has hypercalcemia (Ca²⁺ = 13.5 mg/dL) and a lung mass, which strongly suggests paraneoplastic hypercalcemia due to parathyroid hormone-related protein (PTHrP) secretion. Among lung cancers, squamous cell carcinoma is the most strongly associated with PTHrP-mediated hypercalcemia of malignancy.
Key Associations of Lung Cancers with Paraneoplastic Syndromes:
• Squamous cell carcinoma → PTHrP secretion → Hypercalcemia
• Small-cell lung cancer (SCLC) → SIADH (hyponatremia), ACTH (Cushing’s syndrome), Lambert-Eaton syndrome
• Adenocarcinoma → Hypertrophic osteoarthropathy, thrombophilia (Trousseau syndrome)
• Large-cell carcinoma → HCG secretion (gynecomastia, galactorrhea) (rare)
Why Not the Other Options?
(A) Adenocarcinoma → More commonly associated with hypertrophic osteoarthropathy (digital clubbing, periostitis), not PTHrP-mediated hypercalcemia.
(C) Small-cell lung cancer → Associated with SIADH (hyponatremia) and ACTH production (Cushing’s syndrome) rather than hypercalcemia.
(D) Large-cell carcinoma → Rarely linked to hypercalcemia; more commonly associated with HCG production (paraneoplastic gynecomastia).
Which adenocarcinoma subtype has the best prognosis?
A) Acinar
B) Lepidic
C) Solid
D) Micropapillary
Answer: B) Lepidic
Explanation:
Among adenocarcinoma subtypes, lepidic-predominant adenocarcinoma has the best prognosis. It is characterized by tumor cells growing along intact alveolar walls with minimal invasion, leading to better surgical outcomes and higher survival rates.
Prognosis of Adenocarcinoma Subtypes (Best to Worst):
- Lepidic → Best prognosis (slow-growing, minimal invasion, high survival rates).
- Acinar & Papillary → Intermediate prognosis (more invasive than lepidic but not as aggressive as solid or micropapillary).
- Solid & Micropapillary → Worst prognosis (highly invasive, higher recurrence rates, poor survival).
Why Not the Other Options?
(A) Acinar → Intermediate prognosis, more invasive than lepidic.
(C) Solid → Poor prognosis, aggressive tumor behavior.
(D) Micropapillary → Worst prognosis, associated with early metastasis and high recurrence rates.
Which of the following environmental exposures poses a lung cancer risk similar to or greater than secondhand smoke?
A) Asbestos
B) Radon
C) Mustard gas
D) Chromium
Answer: B) Radon
Explanation:
Radon exposure in homes is a significant environmental risk factor for lung cancer, with a risk similar to or even greater than secondhand smoke. Radon is a radioactive gas that accumulates in enclosed spaces, particularly in poorly ventilated basements and underground dwellings. It is the second leading cause of lung cancer after smoking and a major concern for non-smokers.
Why Not the Other Options?
(A) Asbestos → Strongly linked to lung cancer (especially in smokers) and mesothelioma but generally affects occupational exposures rather than widespread home exposure.
(C) Mustard gas → A known carcinogen but primarily associated with military and industrial exposure rather than common environmental risk.
(D) Chromium → A lung carcinogen, particularly in industrial settings (e.g., metalworking), but does not pose as widespread a risk as radon in residential settings.
Which immunohistochemical marker is most useful in differentiating mesothelioma from lung adenocarcinoma?
A) TTF-1
B) CK7
C) Calretinin
D) Napsin-A
Answer: C) Calretinin
Explanation:
Calretinin is a key immunohistochemical marker that helps differentiate mesothelioma from lung adenocarcinoma. It is positive in mesothelioma but typically negative in lung adenocarcinoma.
Why Not the Other Options?
(A) TTF-1 → Positive in lung adenocarcinoma, but negative in mesothelioma, making it useful for confirming lung adenocarcinoma rather than ruling out mesothelioma.
(B) CK7 → Positive in both lung adenocarcinoma and mesothelioma, so it does not help in differentiation.
(D) Napsin-A → Highly specific for lung adenocarcinoma but not useful in diagnosing mesothelioma.
Thus, calretinin is the best choice for distinguishing mesothelioma from lung adenocarcinoma.
Which of the following genetic mutations is linked to lung cancer in never-smokers?
A) RB mutation
B) EGFR T790M
C) 9p deletion
D) HER2 amplification
Answer: B) EGFR T790M
Explanation:
The EGFR T790M mutation is strongly associated with lung cancer in never-smokers, particularly adenocarcinoma. It is a common driver mutation in non-small-cell lung cancer (NSCLC) and plays a role in resistance to EGFR tyrosine kinase inhibitors (TKIs).
Why Not the Other Options?
(A) RB mutation → Associated with small-cell lung cancer (SCLC), not typically seen in never-smokers.
(C) 9p deletion → Linked to squamous cell carcinoma, often in smokers.
(D) HER2 amplification → Found in a subset of lung adenocarcinomas but less common than EGFR mutations in never-smokers.
Thus, EGFR T790M is the best answer, as it is frequently found in lung adenocarcinoma in never-smokers.
A lung tumor biopsy reveals small cells with scant cytoplasm, finely granular chromatin, and a high mitotic count. Which marker is most likely to be positive?
A) TTF-1
B) p63
C) Napsin-A
D) Chromogranin
Answer: D) Chromogranin
Explanation:
The biopsy findings describe small-cell lung cancer (SCLC), characterized by:
• Small cells with scant cytoplasm
• Finely granular chromatin
• High mitotic count
SCLC is a neuroendocrine tumor, and chromogranin is a key neuroendocrine marker used to confirm its diagnosis.
Why Not the Other Options?
(A) TTF-1 → Can be positive in both adenocarcinoma and SCLC, but it is not neuroendocrine-specific.
(B) p63 → Marker for squamous cell carcinoma, not SCLC.
(C) Napsin-A → Found in adenocarcinoma, absent in SCLC.
Thus, chromogranin is the best answer, as it confirms neuroendocrine differentiation in SCLC.
