Online adaptive radiotherapy (oART) has demonstrated to be feasible to reduce planning target volume (PTV) margins for cervical cancer. To explore the value of reduced margins in oART for 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 cervical cancer could decrease toxicity and achieve more accurate dosimetric coverage. A dose of 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.

Inclusion Criteria:

1. Patients must be informed of the investigational nature of this study and give written informed consent before treatment.
2. Age ≥18 years and ≤ 75 years.
3. Patients with newly histologically confirmed cervical cancer, including squamous cell carcinoma, adenocarcinoma and adenosquamous carcinoma, et al.
4. No evidence of para-aortic metastatic lymph nodes (MLNs) and inguinal lymph nodes on CT, MRI or positron emission tomograph (PET)/CT.
5. No contraindications to CT scanning.
6. No evidence of distant metastasis (FIGO stage IVB).
7. Adequate marrow: neutrophile granulocyte count ≥1.5*10^9/L, hemoglobin ≥ 80 g/L, platelet count ≥100*10^9/L.
8. 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. With common iliac MLNs.
2. Tumor extended to the lower third of the vagina.
3. Tumor spread to mucosa of the bladder or rectum.
4. Prior surgery (including pelvic or para-aortic lymph nodes resection, except for tumor biopsy), radiotherapy or chemotherapy to primary tumor or nodes.
5. Prior malignancy.
6. History of previous radiotherapy to the abdomen or pelvis.
7. Pregnancy or lactation.
8. Active inflammatory bowel disease, or history of severe stomach or duodenal ulcer.
9. Active infection with fever.
10. Patients with unacceptable risk that intracavitary brachytherapy can not be conducted.
11. 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.