Oncologic Surgery Principles US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for Oncologic Surgery Principles. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Oncologic Surgery Principles US Medical PG Question 1: An excisional biopsy is performed and the diagnosis of superficial spreading melanoma is confirmed. The lesion is 1.1 mm thick. Which of the following is the most appropriate next step in management?
- A. Surgical excision with 0.5-1 cm safety margins only
- B. Surgical excision with 1 cm safety margins only
- C. Surgical excision with 1-2 cm safety margins only
- D. Surgical excision with 0.5-1 cm safety margins and sentinel lymph node study
- E. Surgical excision with 1-2 cm safety margins and sentinel lymph node study (Correct Answer)
Oncologic Surgery Principles Explanation: ***Surgical excision with 1-2 cm safety margins and sentinel lymph node study***
- A melanoma with a **Breslow thickness between 1.01 mm and 2.0 mm** (like this 1.1 mm lesion) requires a recommended surgical margin of **1 to 2 cm**.
- For melanomas **≥0.8 mm thickness** (or those with ulceration), a **sentinel lymph node biopsy (SLNB)** is recommended to assess for micrometastasis, as it helps in staging and prognosis.
*Surgical excision with 0.5-1 cm safety margins only*
- A 0.5 cm margin is typically reserved for melanoma *in situ* or extremely thin melanomas (less than or equal to 0.5 mm), and 1 cm for lesions 0.51 to 1.0 mm, which is too narrow for a 1.1 mm lesion.
- This option incorrectly omits the **sentinel lymph node study**, which is indicated for a melanoma of this thickness.
*Surgical excision with 1 cm safety margins only*
- While 1 cm is a common margin for lesions up to 1.0 mm, a 1.1 mm melanoma usually warrants a slightly wider margin, ideally 1-2 cm.
- This option also fails to include the **sentinel lymph node study**, which is crucial for staging melanomas ≥0.8 mm thickness.
*Surgical excision with 0.5-1 cm safety margins and sentinel lymph node study*
- The recommended surgical margin for a 1.1 mm melanoma is at least **1 cm, preferably between 1 and 2 cm**, making a 0.5-1 cm range insufficient.
- Although it correctly includes the sentinel lymph node study, the **surgical margin is inadequate** for the given Breslow thickness.
*Surgical excision with 1-2 cm safety margins only*
- While the **1-2 cm surgical margin** is appropriate for a 1.1 mm melanoma, this option **incorrectly excludes the sentinel lymph node study**.
- The sentinel lymph node biopsy is a critical part of the staging and management plan for melanomas of this thickness to detect potential nodal involvement.
Oncologic Surgery Principles US Medical PG Question 2: A 64-year-old woman presents to the surgical oncology clinic as a new patient for evaluation of recently diagnosed breast cancer. She has a medical history of type 2 diabetes mellitus for which she takes metformin. Her surgical history is a total knee arthroplasty 7 years ago. Her family history is insignificant. Physical examination is notable for an irregular nodule near the surface of her right breast. Her primary concern today is which surgical approach will be chosen to remove her breast cancer. Which of the following procedures involves the removal of a portion of a breast?
- A. Arthroplasty
- B. Lumpectomy (Correct Answer)
- C. Vasectomy
- D. Mastectomy
- E. Laminectomy
Oncologic Surgery Principles Explanation: ***Lumpectomy***
- A **lumpectomy** is a surgical procedure that removes the **breast cancer tumor** and a small margin of surrounding healthy tissue, preserving most of the breast.
- This procedure is a common treatment for early-stage breast cancer and is often followed by radiation therapy.
*Arthroplasty*
- **Arthroplasty** is a surgical procedure to **repair or replace a joint**, typically due to arthritis or injury.
- The patient's history of a total knee arthroplasty indicates this procedure was performed on her knee, not her breast.
*Vasectomy*
- A **vasectomy** is a surgical procedure for **male sterilization**, involving the cutting and sealing of the vas deferens.
- This procedure is unrelated to breast cancer treatment or breast surgery.
*Mastectomy*
- A **mastectomy** involves the **complete surgical removal of the entire breast**, often including the nipple and areola.
- While it is a breast surgery, it removes the *entire* breast, not just a portion.
*Laminectomy*
- A **laminectomy** is a surgical procedure that removes a portion of the **vertebra (lamina)** to relieve pressure on the spinal cord or nerves.
- This procedure is for spinal conditions and is entirely unrelated to breast cancer surgery.
Oncologic Surgery Principles US Medical PG Question 3: A 58-year-old man presents with lower back pain that started a couple of weeks ago and is gradually increasing in severity. At present, he rates the intensity of the pain as 6/10. There is no radiation or associated paresthesias. There is no history of trauma. Past medical history is significant for aggressive squamous cell carcinoma of the right lung status post surgical resection followed by adjunct chemotherapy and radiation therapy that was completed 6 months ago. A technetium bone scan reveals metastatic lesions in the lumbar vertebrae at levels L2–L4. The physician explains to the patient that these are likely metastatic lesions from his primary lung cancer. Which of the following best describes the mechanism that most likely led to the development of these metastatic lesions?
- A. Transcoelomic
- B. Lymphatic spread
- C. Collagenase produced by cancer cells dissolves the basement membrane and aids in cellular invasion
- D. Hematogenous spread (Correct Answer)
- E. PTH (parathormone)-related protein production by tumor cells
Oncologic Surgery Principles Explanation: ***Hematogenous spread***
- Lung cancer frequently metastasizes to bone via the **hematogenous (bloodstream) route**, especially to the spine, pelvis, and long bones.
- The rich vascular supply of the vertebrae makes them a common site for metastases from many primary cancers, including those of the lung.
*Transcoelomic*
- **Transcoelomic spread** occurs when tumor cells spread directly within body cavities, such as the peritoneal or pleural cavity.
- This mechanism is typical for cancers of organs within these cavities, like ovarian cancer spreading within the peritoneum, and is not the primary route for lung cancer to distant bone.
*Lymphatic spread*
- **Lymphatic spread** involves tumor cells traveling through the lymphatic system to regional lymph nodes.
- While lung cancer commonly spreads to mediastinal and hilar lymph nodes, it is usually not the direct mechanism for distant bone metastases, which typically involve the circulatory system.
*Collagenase produced by cancer cells dissolves the basement membrane and aids in cellular invasion*
- While **collagenase production** and **basement membrane degradation** are crucial steps in local tumor invasion and intravasation (entering blood or lymphatic vessels), they describe the *how* a cell invades, not the *route* of distant metastasis.
- This mechanism facilitates the initial escape of cancer cells from the primary tumor but does not define the subsequent spread to distant sites like bone.
*PTH (parathormone)-related protein production by tumor cells*
- **PTH-related protein (PTHrP) production** by tumor cells can lead to **hypercalcemia of malignancy** due to its osteolytic effects.
- While this is a common paraneoplastic syndrome associated with squamous cell carcinoma of the lung, it is a *consequence* or *effect* of the tumor and does not describe the *mechanism of metastasis* itself.
Oncologic Surgery Principles US Medical PG Question 4: A 58-year-old male undergoes a surveillance colonoscopy in which a 2 cm adenoma is identified and removed. Had this adenoma not been excised, the patient would have been at risk of progression to carcinoma. Which of the following is the final mutational step in the progression from adenoma to carcinoma?
- A. p53 inactivation (Correct Answer)
- B. APC mutation
- C. COX-2 overexpression
- D. SMAD 2/4 loss
- E. K-ras mutation
Oncologic Surgery Principles Explanation: ***p53 inactivation***
- **p53 loss of function** is typically the final genetic event in the **adenoma-to-carcinoma sequence**, facilitating unrestricted cell growth and preventing apoptosis in dysplastic cells.
- The **p53 tumor suppressor gene** normally checkpoints cell division and induces programmed cell death, making its inactivation critical for malignant transformation.
*APC mutation*
- **APC (adenomatous polyposis coli) mutation** is often the **initiating event** in colorectal adenoma formation, leading to aberrant crypt foci and polyp formation.
- While critical for early tumor genesis, it does not represent the final step in progression to invasive carcinoma.
*COX-2 overexpression*
- **Cyclooxygenase-2 (COX-2) overexpression** leads to increased prostaglandin production, which can promote cell proliferation, angiogenesis, and inhibit apoptosis.
- It is an important factor in tumor growth and progression but occurs earlier in the sequence and is not the terminal mutational step for carcinoma.
*SMAD 2/4 loss*
- **SMAD 2/4 loss of function** disrupts the **TGF-β signaling pathway**, which normally inhibits cell growth and promotes differentiation.
- This event typically occurs in the late adenoma stage, contributing to dysplasia, but **p53 inactivation** is considered the final critical step for full malignant transformation.
*K-ras mutation*
- **K-ras mutation** is a well-known event in the **adenoma-to-carcinoma sequence**, occurring earlier than p53 inactivation, usually in intermediate-sized adenomas.
- It leads to constitutive activation of the RAS/MAPK pathway, promoting cell growth and survival, but generally before full malignant transformation.
Oncologic Surgery Principles US Medical PG Question 5: Five days after undergoing an open colectomy and temporary colostomy for colon cancer, a 73-year-old man develops severe pain and swelling of the left calf. He was diagnosed with colon cancer 3 months ago. He has hypothyroidism and hypertension. His father died of colon cancer at the age of 68. He does not smoke. Prior to admission, his medications included levothyroxine, amlodipine, and carvedilol. Since the surgery, he has also been receiving unfractionated heparin, morphine, and piperacillin-tazobactam. He is 172 cm (5 ft 8 in) tall and weighs 101 kg (223 lb); BMI is 34.1 kg/m2. He appears uncomfortable. His temperature is 38.1°C (100.6°F), pulse is 103/min, and blood pressure is 128/92 mm Hg. Examination shows multiple necrotic lesions over bilateral thighs. The left calf is erythematous, tender, and swollen. Dorsiflexion of the left foot elicits pain behind the knee. The abdomen is soft and nontender. There is a healing midline incision and the colostomy is healthy and functioning. The remainder of the examination shows no abnormalities. Laboratory studies show:
Hemoglobin 13.6 g/dL
Leukocyte count 12,100/mm3
Platelet count 78,000/mm3
Prothrombin time 18 seconds (INR = 1.1)
Activated partial thromboplastin time 46 seconds
Serum
Na+ 138 mEq/L
Cl- 103 mEq/L
K+ 4.1 mEq/L
Urea nitrogen 18 mg/dL
Glucose 101 mg/dL
Creatinine 1.1 mg/dL
Which of the following is the most appropriate next step in management?
- A. Switch from unfractionated heparin to warfarin therapy
- B. Transfuse platelet concentrate
- C. Administer vitamin K
- D. Switch from unfractionated heparin to argatroban therapy (Correct Answer)
- E. Administer fresh frozen plasma
Oncologic Surgery Principles Explanation: ***Switch from unfractionated heparin to argatroban therapy***
- The patient's presentation with new **thrombosis (severe pain and swelling of the left calf)**, **thrombocytopenia (platelet count 78,000/mm3)**, and recent exposure to **unfractionated heparin (UFH)** is highly suggestive of **Heparin-Induced Thrombocytopenia (HIT) with thrombosis (HITT)**.
- In suspected or confirmed HIT, UFH must be immediately discontinued, and a **direct thrombin inhibitor (DTI)** like **argatroban** should be initiated to prevent further thrombosis.
*Switch from unfractionated heparin to warfarin therapy*
- While warfarin is used for long-term anticoagulation, it should **not be initiated as monotherapy in acute HIT** due to the risk of **venous limb gangrene** and further thrombosis during the initial phase of warfarin action (due to initial procoagulant effect).
- Warfarin can only be started **after platelet counts have recovered** and a non-heparin anticoagulant (like a DTI) has been administered for at least 5 days, given there is an overlap period.
*Transfuse platelet concentrate*
- Platelet transfusions are generally **contraindicated in HIT** because they can worsen the prothrombotic state by providing more substrate for platelet activation, potentially exacerbating thrombosis.
- Platelet transfusions are reserved for **life-threatening bleeding** in patients with HIT, which is not the case here.
*Administer vitamin K*
- Vitamin K is the antidote for **warfarin** overdose and has no role in the management of HIT. The patient's PT/INR is only mildly elevated, likely due to heparin and not warfarin, as he was not on warfarin.
- Administering vitamin K would not address the underlying pathology of HIT and would not be beneficial.
*Administer fresh frozen plasma*
- Fresh frozen plasma (FFP) contains clotting factors and is used to reverse coagulopathy in cases of **severe bleeding or factor deficiencies**, or for rapid reversal of warfarin.
- It is **not indicated for HIT**, as HIT is a prothrombotic condition involving platelet activation, not a deficiency in clotting factors that would be corrected by FFP.
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