## **Core Concept**
The International Federation of Gynecology and Obstetrics (FIGO) staging system is used for cervical cancer staging. It primarily relies on clinical examination, imaging, and surgical findings. The involvement of the endometrium in cervical cancer indicates a more advanced stage.

## **Why the Correct Answer is Right**
The correct answer, **FIGO Stage IIIA**, is appropriate when there is tumor invasion to the uterine corpus (endometrium) without parametrial involvement. This classification helps in determining the prognosis and treatment plan for patients with cervical cancer.

## **Why Each Wrong Option is Incorrect**
* **Option A: FIGO Stage I**: This stage is incorrect because it refers to carcinoma limited to the cervix uteri. Endometrial involvement would classify it at a more advanced stage.
* **Option B: FIGO Stage II**: This stage involves the uterus but not the parametria or the lower third of the vagina. However, it does not specifically account for endometrial involvement.
* **Option D: FIGO Stage IV**: This stage involves distant metastasis, which is not indicated by endometrial involvement alone.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that FIGO staging is clinical and based on physical examination, imaging, and sometimes surgical findings. Endometrial involvement changes the staging to **IIIA**, which is crucial for treatment planning and prognosis.

## **Correct Answer: C. FIGO Stage IIIA.**