Which of the following is the most common histological type of prostate cancer?

Explanation

## Histological Classification of Prostate Cancer **Key Point:** Adenocarcinoma accounts for >95% of all prostate cancers and is the standard histological type unless otherwise specified. ### Frequency Distribution | Histological Type | Frequency | Clinical Significance | | --- | --- | --- | | Adenocarcinoma | >95% | Most common; responds to hormonal therapy | | Squamous cell carcinoma | <1% | Rare; aggressive; hormone-resistant | | Small cell carcinoma | <1% | Rare; neuroendocrine; poor prognosis | | Transitional cell carcinoma | <1% | Arises from bladder; rare in prostate | ### Adenocarcinoma Subtypes **High-Yield:** Acinar adenocarcinoma is the most common subtype, accounting for ~90% of adenocarcinomas. Other subtypes include: - Ductal adenocarcinoma (aggressive, higher grade) - Mucinous adenocarcinoma (rare, mucin-producing) - Signet-ring cell adenocarcinoma (rare, poor prognosis) **Clinical Pearl:** The vast majority of prostate cancers are hormone-sensitive adenocarcinomas arising from the peripheral zone, which explains the effectiveness of androgen deprivation therapy (ADT) as first-line treatment for advanced disease. **Warning:** Do not confuse prostate adenocarcinoma with adenocarcinoma of the bladder or other urinary tract malignancies — histology and origin differ significantly.