**Core Concept**
The spread of prostate cancer to the vertebral bodies is a common complication, often resulting in bone metastases. This phenomenon is characterized by the deposition of malignant cells in the bone marrow, leading to structural damage and characteristic radiographic findings.

**Why the Correct Answer is Right**
The most common route of spread of prostate cancer to the vertebral bodies is through the hematogenous route, specifically via the venous system. The cancer cells from the prostate gland enter the bloodstream and are carried to the vertebrae, where they lodge and proliferate, causing destruction of the bone matrix and leading to sclerosis and collapse. This process is facilitated by the rich vascular supply of the bone marrow and the presence of osteoblastic activity, which promotes the deposition of new bone tissue.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the lymphatic system is not the primary route of spread for prostate cancer to the vertebral bodies. While lymphatic spread can occur, it is less common than hematogenous spread.
* **Option B:** This option is incorrect because the spread of prostate cancer to the vertebral bodies is not typically through direct extension from adjacent structures. The prostate gland is located anterior to the rectum and the bladder, and direct extension to the vertebral bodies is not a common mechanism.
* **Option C:** This option is incorrect because the spread of prostate cancer to the vertebral bodies is not typically through the perineural route. While perineural invasion can occur in prostate cancer, it is not the primary mechanism of spread to the vertebral bodies.

**Clinical Pearl / High-Yield Fact**
Prostate cancer spreads to the vertebral bodies through the hematogenous route, often resulting in characteristic radiographic findings of sclerosis and collapse. This phenomenon is a common complication of advanced prostate cancer and can have significant implications for patient management and prognosis.

**Correct Answer:** D.