Online adaptive radiotherapy (oART) has demonstrated to be feasible to reduce planning target volume (PTV) margins for postoperative treatment of endometrial and cervical cancer. To explore the value of reduced margins in oART for postoperative treatment of endometrial and cervical cancer, we conducted a prospective clinical trial to determine the clinical efficacy and toxicity of reduced margins.

This is an investigator-initiated efficacious, single-center, open-label clinical trial study. This study hypothesizes that the use of reduced PTV margins in oART for postoperative treatment of endometrial and cervical cancer could decrease toxicity and achieve more accurate dosimetric coverage. A dose of 45 or 50.4 Gy is delivered to clinical target volume (CTV) with reduced margin oART. Patients receive cisplatin based concurrent chemotherapy. The primary endpoint is acute toxicity. The first 10 patients were included in the study that have demonstrated the feasibility of reducing the margin (ClinicalTrials.gov ID: NCT05682950).

Inclusion Criteria:

1. Patients must be informed of the investigational nature of this study and give written informed consent before treatment.
2. Postoperative endometrial and cervical cancer patients with pathologically confirmed no residual tumor at the resection margin and no evidence of distant metastasis (FIGO stage IVB).
3. Pathological findings indicate risk factors and adjuvant radiotherapy are prescribe.
4. Karnofsky score ≥ 70.
5. Subjects aged ≥ 18 years and ≤ 70 years.
6. No evidence of para-aortic metastatic lymph nodes.
7. No contraindications to CT scanning.
8. Subjects must be able to cooperate in completing the entire study.
9. Adequate marrow: neutrophile granulocyte count ≥1.5*10^9/L, hemoglobin ≥ 80 g/L, platelet count ≥100*10^9/L.
10. Normal liver and kidney function: Creatinine (Cr) < 1.5 mg/dl, Alanine Aminotransferase (ALT), Aspartate Aminotransferase (AST) < 2*upper limit of normal (ULN).

Exclusion Criteria:

1. Subjects who have received prior pelvic radiotherapy.
2. Subjects with other primary malignancies.
3. Subjects with contraindications to radiotherapy, as determined by the investigators.
4. Any severe disease which may bring unacceptable risk or affect the compliance of the trial, for example, unstable cardiac disease requiring treatment, renal disease, chronic hepatitis, diabetes with poor control, and emotional disturbance.
5. Active infection with fever.
6. Active inflammatory bowel disease.