**Core Concept:** Post-operative radiotherapy in a patient operated for Ca-endometrium is a treatment modality used to reduce the risk of cancer recurrence and improve survival rates in certain cases of endometrial cancer.

The question is asking which of the given options does not require post-operative radiotherapy. We should understand the indications for this treatment to answer correctly.

**Why the Correct Answer is Right:**

The correct answer, **Option A**, is "endometrial cancer with stage I disease" because:

- Radiotherapy is typically recommended for patients with more advanced stages of endometrial cancer to improve survival rates and reduce the risk of recurrence.
- In stage I disease, the risk of recurrence and the need for adjuvant therapy is generally lower, and the benefits of radiotherapy may not outweigh the potential risks and side effects.

**Why Each Wrong Option is Incorrect:**

**Option B:** "endometrial cancer with low-grade disease" is incorrect because:

- Low-grade endometrial cancers have a better prognosis and the risk of recurrence is generally lower compared to high-grade cancers.
- For low-grade endometrial cancer, surgical margins and lymph nodes are more crucial factors in determining prognosis, and radiotherapy may not be necessary in all cases.

**Option C:** "endometrial cancer with early-stage disease" is incorrect because:

- Early-stage endometrial cancer can still have varying degrees of risk for recurrence and benefit from radiotherapy, depending on factors like histopathology, lymphovascular space invasion, and surgical margins.
- The statement is too broad, and individual cases should be evaluated based on specific criteria.

**Option D:** "endometrial cancer with high-grade disease" is incorrect because:

- High-grade endometrial cancers are associated with a higher risk of recurrence and may benefit from adjuvant therapy like radiotherapy, particularly when accompanied by factors like positive margins or lymphovascular space invasion.
- The statement is too broad, and individual cases should be evaluated based on specific criteria, such as histopathology, grading, and surgical margins.

**Correct Answer Explanation:**

In post-operative management of endometrial cancer, radiotherapy is typically recommended for specific cases, not based on a broad statement like "endometrial cancer." Each case should be evaluated individually, considering factors like histopathology, grading, and surgical margins to determine the necessity of radiotherapy.

**Why the Correct Answer is Right:**

The correct answer, **Option E**, is "endometrial cancer with grade 1 or 2 disease and negative margins."

- Grade 1 or 2 endometrial cancer generally has a better prognosis and a lower risk of recurrence, indicating that radiotherapy may not be necessary.
- Negative surgical margins indicate the cancer has not invaded the myometrium, which is a favorable prognostic factor.

**Why Each Wrong Option is Incorrect:**

**Option F:** "endometrial cancer with grade 3 disease" is incorrect because:

- Grade 3 endometrial cancer has a poorer prognosis and higher risk of recurrence, making radiotherapy more likely to