A metastatic tumour least common in –
**Core Concept**
The question tests knowledge of metastatic tumor sites, focusing on the least common location. **Metastasis** involves the spread of cancer cells from the primary site to distant organs via the bloodstream or lymphatic system.
**Why the Correct Answer is Right**
Since the correct answer isn't provided, let's discuss general principles. The least common sites for metastasis are typically those with less blood flow or specific barriers to tumor cell seeding, such as the **heart** or **skeletal muscle**.
**Why Each Wrong Option is Incorrect**
**Option A:** Without knowing the options, we can't directly address each. However, typically, **lung**, **liver**, and **bone** are common sites for metastasis due to their high blood flow.
**Option B:** Similarly, without specifics, we can say that **brain** metastases are less common than lung or liver but can occur, especially from **breast**, **lung**, or **melanoma** primaries.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that the distribution of metastases depends on the primary tumor type and its venous drainage. For instance, **tumors of the gastrointestinal tract** often metastasize to the **liver** due to the hepatic portal vein.
**Correct Answer:** Not provided in the query.