A 58-year-old postmenopausal woman presents with abnormal uterine bleeding. Endometrial biopsy reveals grade 1 endometrioid adenocarcinoma confined to the inner half of the myometrium (stage IB). She is medically fit for surgery. What is the drug of choice for adjuvant treatment after total abdominal hysterectomy and bilateral salpingo-oophorectomy?

Explanation

## Adjuvant Treatment of Stage IB Grade 1 Endometrial Carcinoma **Key Point:** For stage IB (myoinvasion ≤50% — inner half) **grade 1** endometrioid adenocarcinoma in a medically fit patient, the standard adjuvant treatment after TAH-BSO is **vaginal brachytherapy (VBT) alone** — not systemic chemotherapy. ### Risk Stratification in Early-Stage Endometrial Cancer (NCCN / ESGO-ESTRO-ESP 2021) | Risk Category | Features | Adjuvant Treatment | |---|---|---| | **Low-risk** | Stage IA, grade 1–2, no LVSI | Observation | | **Low-intermediate-risk** | Stage IB, grade 1–2, no LVSI, age <60 | VBT (optional) | | **High-intermediate-risk** | Stage IB grade 1–2 + LVSI, or grade 3 without LVSI, age ≥60 | VBT ± EBRT | | **High-risk** | Stage IB grade 3 + LVSI, serous/clear cell, carcinosarcoma, stage III | Chemotherapy ± RT | **High-Yield:** The stem describes **stage IB (inner half = ≤50% myoinvasion), grade 1, no mention of LVSI** — this is **low-to-low-intermediate risk**. Per GOG-99 and PORTEC-1 trials, VBT reduces vaginal vault recurrence with minimal systemic toxicity and is the preferred adjuvant modality. Systemic chemotherapy (paclitaxel–carboplatin) is reserved for **high-risk** features such as grade 3 histology, lymphovascular space invasion (LVSI), serous or clear-cell subtypes, or stage III–IV disease. ### Why Other Options Are Incorrect - **A) Paclitaxel and carboplatin:** Appropriate for high-risk stage IB (grade 3, LVSI) or advanced-stage disease — not for grade 1, inner-half invasion. - **C) Doxorubicin and cisplatin:** An older regimen (GOG-177) largely replaced by paclitaxel–carboplatin; not indicated here. - **D) Tamoxifen:** Has no established role as adjuvant therapy in endometrial carcinoma; it is actually associated with increased endometrial cancer risk when used for breast cancer. **Clinical Pearl:** VBT (vaginal brachytherapy) targets the vaginal cuff — the most common site of local recurrence in early endometrial cancer — without the systemic toxicity of chemotherapy. PORTEC-2 confirmed VBT is non-inferior to EBRT for locoregional control in intermediate-risk disease. **Mnemonic:** **Grade 1 + Inner half = VBT** — save chemotherapy for grade 3, LVSI, or advanced stage. *References: NCCN Guidelines Uterine Neoplasms v2.2024; PORTEC-2 trial (Nout et al., Lancet 2010); GOG-99 (Keys et al., Gynecol Oncol 2004).*