**Question:** Most common site of development of carcinoma of prostate is

A. **Bone marrow
B. **Genitourinary system
C. **Digestive system
D. **Respiratory system

**Correct Answer:** **B. Genitourinary system**

**Core Concept:** Prostate cancer is a type of malignancy that originates from the epithelial cells of the prostate gland. The prostate gland is an accessory sex gland located in the male reproductive system, responsible for producing prostatic acid phosphatase (PAP), prostatic specific antigen (PSA), and seminal fluid.

**Why the Correct Answer is Right:** Carcinoma of the prostate most commonly develops from the transitional zone of the prostate gland, which is responsible for producing prostatic fluid and seminal vesicle fluid. The transitional zone is characterized by high rates of cell division and is more susceptible to malignant changes compared to the peripheral and peripheral interzone zones.

**Why Each Wrong Option is Incorrect:**

A. Bone marrow is not the primary site for prostate cancer development. While prostate cancer can sometimes spread to the bone marrow, the primary tumor originates in the prostate gland.

B. The respiratory system is not the site of origin for prostate cancer. Prostate cancer develops in the male reproductive system.

C. The digestive system is not the primary site for prostate cancer development. Prostate cancer arises from the epithelial cells of the prostate gland, not from cells within the gastrointestinal tract.

D. The respiratory system is not the primary site for prostate cancer development. As mentioned previously, prostate cancer develops in the male reproductive system, not the respiratory system.

**Clinical Pearl:** Prostate cancer is the second most common cancer in men, after skin cancer. Early detection and regular screening can lead to improved prognosis and treatment outcomes. A PSA test is the most common method used for early detection and monitoring prostate cancer treatment progress.