UPSC-CMS 2020 — Pathology
2 Previous Year Questions with Answers & Explanations
All of the following are major subtypes of breast cancer based on Gene array analysis EXCEPT:
The most common site for osteosarcoma is:
UPSC-CMS 2020 - Pathology UPSC-CMS Practice Questions and MCQs
Question 1: All of the following are major subtypes of breast cancer based on Gene array analysis EXCEPT:
- A. Luminal A and Luminal B
- B. Triple negative
- C. Her-2 receptor positive
- D. Estrogen receptor positive (Correct Answer)
Explanation: ***Oestrogen receptor positive*** - While **estrogen receptor (ER) positivity** is a critical prognostic and predictive marker in breast cancer, it is a single marker, not a distinct intrinsic subtype encompassing broader genomic categorization [1]. - The intrinsic subtypes are based on gene expression profiles that cluster tumors into biologically distinct groups, such as Luminal A, Luminal B, HER2-enriched, and Basal-like (including Triple Negative) [3]. *Luminal A and Luminal B* - These are major intrinsic subtypes characterized by the expression of **hormone receptors** (ER and/or PR) and differing in their proliferation rates [2]. - **Luminal A** generally has high ER, low proliferation, and a good prognosis, while **Luminal B** often has higher proliferation (e.g., higher Ki-67) and a slightly worse prognosis [2]. *Triple negative* - This is a major intrinsic subtype (**Basal-like**) defined by the absence of **estrogen receptors (ER)**, **progesterone receptors (PR)**, and **HER2 overexpression** [1], [4]. - It often correlates with a more aggressive clinical course and specific treatment approaches [4]. *Her-2 receptor positive* - This is a major intrinsic subtype characterized by the **overexpression or amplification of the HER2 gene** [3]. - These cancers are often aggressive but respond well to targeted therapies like trastuzumab [3], [4]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Breast, pp. 1064-1066. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 10th ed. The Breast, pp. 1059-1060. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Breast, p. 1060. [4] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 258-259.
Question 2: The most common site for osteosarcoma is:
- A. Distal femur (Correct Answer)
- B. Proximal humerus
- C. Proximal femur
- D. Distal humerus
Explanation: ***Distal femur*** - The **distal femur** is the most frequent site of involvement for **osteosarcoma**, accounting for approximately 40% of all cases [1]. - This region, along with the proximal tibia and proximal humerus, constitutes the most common locations for this primary malignant bone tumor [1]. *Proximal humerus* - While the **proximal humerus** is a common site for osteosarcoma, it is less frequent than the distal femur [1]. - It ranks third in incidence after the distal femur and proximal tibia [1]. *Proximal femur* - The **proximal femur** can be affected by osteosarcoma, but it is a relatively less common site compared to the distal femur. - Osteosarcomas tend to occur around the **growth plates** of long bones [1]. *Distal humerus* - The **distal humerus** is an uncommon site for the development of osteosarcoma. - It is much less frequently involved than the other major long bone metaphyses. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1200-1202.