Most common carcinoma of breast is –
**Core Concept**
The question is testing the most common carcinoma of the breast, which refers to the type of breast cancer that affects the highest number of individuals. Breast cancer is a heterogeneous disease with various subtypes, each with distinct characteristics and clinical implications.
**Why the Correct Answer is Right**
The most common carcinoma of the breast is invasive ductal carcinoma (IDC). IDC accounts for approximately 70-80% of all breast cancers and arises from the ductal epithelium of the breast. It is characterized by the invasion of cancer cells into the surrounding breast tissue, which can lead to metastasis and poor prognosis if left untreated. IDC is often associated with mutations in the BRCA1 and BRCA2 genes, which are tumor suppressor genes that play a crucial role in DNA repair.
**Why Each Wrong Option is Incorrect**
**Option A:** Invasive lobular carcinoma is a type of breast cancer that originates from the lobular glands of the breast. While it is a significant subtype, it is less common than IDC, accounting for approximately 10-15% of all breast cancers.
**Option B:** Ductal carcinoma in situ (DCIS) is a non-invasive form of breast cancer where cancer cells are confined to the ductal epithelium and have not invaded surrounding tissue. Although DCIS is a common precursor to IDC, it is not considered a carcinoma in the classical sense.
**Option C:** Medullary carcinoma is a rare subtype of breast cancer that accounts for less than 5% of all breast cancers. It is characterized by a distinct histological appearance and often presents with a favorable prognosis.
**Clinical Pearl / High-Yield Fact**
The most important factor in determining the prognosis of breast cancer is the presence of lymph node metastasis. Patients with lymph node-positive breast cancer have a significantly poorer prognosis than those with lymph node-negative disease.
**Correct Answer: C. Medullary carcinoma is a rare subtype of breast cancer that accounts for less than 5% of all breast cancers. It is characterized by a distinct histological appearance and often presents with a favorable prognosis.