Question 11: A 49 year old female presents with a breast lump. Which of the following findings is in accordance with basal-like breast cancer?
- A. ER-, PR-, HER2- (Correct Answer)
- B. ER+, PR-, HER2-
- C. ER-, PR-, HER2+
- D. ER+, PR+, HER2-
Explanation: ***ER-, PR-, HER2-***
- **Basal-like breast cancer** is characterized by its **triple-negative** status, meaning it does not express estrogen receptor (ER), progesterone receptor (PR), or human epidermal growth factor receptor 2 (HER2) [1].
- This specific immunophenotype is crucial for diagnosis and influences treatment strategies, as these cancers do not respond to therapies targeting these receptors [1].
*ER+, PR-, HER2-*
- This profile describes a **hormone-sensitive** cancer (ER positive) but without PR or HER2 expression.
- While it responds to endocrine therapies, it is distinct from basal-like cancer due to its ER positivity.
*ER-, PR-, HER2+*
- This profile indicates a cancer that is **HER2-positive**, meaning it overexpresses HER2, and can be targeted with anti-HER2 therapies like trastuzumab.
- This is a separate molecular subtype of breast cancer often referred to as HER2-enriched, which is distinct from basal-like [2].
*ER+, PR+, HER2-*
- This is the most common subtype, known as **luminal A** or **luminal B** depending on grade and Ki-67 expression, characterized by sensitivity to endocrine therapy [2].
- This hormone receptor-positive and HER2-negative profile is very different from the triple-negative basal-like breast cancer.
**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. 9th ed. The Breast, p. 1060.