Which histological type accounts for approximately 80% of all endometrial carcinomas and is associated with estrogen dependence?

Explanation

## Endometrial Carcinoma Histological Types **Key Point:** Endometrioid adenocarcinoma is the most common histological type of endometrial carcinoma, accounting for 70–80% of cases. ### Endometrioid Adenocarcinoma - **Frequency:** 70–80% of all endometrial cancers - **Estrogen dependence:** Strongly associated with unopposed estrogen exposure - **Risk factors:** Obesity, diabetes, nulliparity, late menopause, PCOS - **Grade:** Usually low to intermediate grade (FIGO grades 1–2) - **Prognosis:** Generally favorable when detected early (5-year survival ~85%) - **Molecular features:** Often shows PTEN loss, KRAS mutations, microsatellite instability (MSI-H) ### Other Histological Types (Less Common) | Type | Frequency | Estrogen Dependence | Grade | Prognosis | | --- | --- | --- | --- | --- | | Serous papillary | 5–10% | No | High (3) | Poor | | Clear cell | 1–5% | No | High (3) | Poor | | Adenosquamous | 1–3% | Variable | High | Poor | | Mucinous | <1% | Yes | Low–Int | Favorable | **High-Yield:** Endometrioid carcinoma is **estrogen-dependent**, whereas serous and clear cell types are **estrogen-independent** and have aggressive behavior despite lower frequency. **Clinical Pearl:** The presence of squamous differentiation in endometrioid carcinoma (adenoacanthoma) does NOT worsen prognosis if the glandular component is low-grade. **Mnemonic:** **"ACES"** for aggressive endometrial types: - **A**denosquamous - **C**lear cell - **E**ndometrial stromal sarcoma - **S**erous papillary All are non-estrogen-dependent, high-grade, and carry poor prognosis.