Introduction: Cervical cancer is the seventh most common and the eighth deadliest cancer in Chinese women. In spite of the advances in multimodality treatment regimens, there were 15-40% patients suffering from recurrence within initial irradiated field\[1, 2\], of which 95% recurrence occurred within 2 years and only 20% of them could be treated by salvage treatment\[3-6\]. there were controversies on how recurrent cervical cancer within the irradiated field should be dealt with. Surgery such as pelvic extenteration had to remove involved organs including intestine, rectum or bladder and sometimes led to severe complications and a poor quality of life. After the initial 45-50Gy irradiated to the whole pelvis, it seemed to have minimal space of further re-irradiation for recurrent disease as conventional radiotherapy was applied when considering late toxicities of organs at risk. The radiation dose for pelvic structures received will reach 45-50 Gy, almost reached the upper limits of normal tissues. For recurrent cervical cancer patients receiving retreatment by radiotherapy, the toxicity increased by 30%-56%\[2\] when conventional technique was applied, toxicities restricted sufficient treatments to the recurrence disease leading to a poor prognosis, which was usually less than a year \[8\]. IMRT has an advantage over conventional techniques because of delivering a high dose to target volume while sparing organs at risk which were previously irradiated in the primary radiotherapy. We have a five years' experience using IMRT to treat patients with recurrent disease within the previously irradiated field and most of patients showed good response and tolerable complication. According to our retrospective research (publishing), thirty-three patients made a median survival time of 14.06 months, one year overall survival was 55% and 2 year overall survival was 22%, which were better than the results of one year survival 10-20% from previous studies \[8\]. For further evidence, we designed this prospective clinical trial to evaluate the efficacy and safety when using intensity modulated radiotherapy to treat patients with recurrent cervical cancer within the previously irradiated field.

Methods: Sixty patients with recurrent cervical cancer within the previously irradiated field will be prospectively enrolled in this study. Only patients meeting both the including criteria and exclusion criteria will be carefully selected considering potential severe toxicities. A primary course of 36Gy will be prescribed to the recurrent site and a further 9-24Gy of dose escalation will be prescribed to the gross tumor volume in the second course according to the toxicities and the shrinkage of tumor to the irradiation. Intensity Modulated RadioTherapy (IMRT) will be chosen for dose delivery as this technique gives sufficient dose to target volume meanwhile sparing organs at risk. Weekly cisplatin of 30mg/m2 by five weeks will be administrated intravenously to the selected patients.

Outcome measurements: Toxicities will evaluated using Common Terminology Criteria for Adverse Events version 4.0 (CTCAE 4.0). Acute toxicities will be monitored weekly until one month after the completion of radiotherapy and chemotherapy. Then late toxicities will be recorded by monthly following-up. Three year's progression free survival (3y PFS) and three year's recurrence free survival(3y RFS) are the major endpoints of this study. Every three months the patients will be evaluated with necessary modalities such as physical examination, blood test, radiography, computed tomography, magnetic resonance and/or positron emission topography until three year after the last radiotherapy/chemotherapy.