Failure Pattern in Patients With Intermediate- to High-Risk Cervical Cancer Treated With Postoperative Chemoradiation Using CT-Based Nodal-CTV Delineation

To validate the appropriateness of nodal-CTV delineating pelvic radiation therapy by assessing failure pattern in patients with cervical cancer receiving postoperative concurrent chemoradiation. Sixty-eight patients with intermediate to high risk cervical cancer, proven to have pelvic lymph node metastasis (pN1) or parametrial involvement after surgery, who received postoperative cisplatin-based concurrent chemoradiation between 2001 and 2010 were entered into the study. The median age was 47 years (range, 26-71 years). FIGO stage was IB1 in 26, IB2 in 23, IIA1 in 3, IIA2 in 3, and IIB in 13. There were 34 patients with pN1 for whom, numbers of positive node ranged from 1 to 11 (median: 2). Histopathological tumor size ranged from 19 to 90 mm. All patients were treated with 3-dimensional nodal-CTV delineating pelvic radiation therapy. Major blood vessels were identified and contoured on CT simulation images. Margins of 7 to 15 mm around major pelvic blood vessels were added to define nodal-CTV. The RTOG guideline was followed after its publication. CTV was expanded to delineate individualized planning target volume (PTV). For most patients, traditional 4-field technique was used with 5 mm width MLCs conforming the PTV drawn on digitally reconstructed radiographs. Failure patterns in relation to nodal-CTV were clinically evaluated. With a median follow-up of 55 months, 15 patients developed recurrence; 9 in patients with pN1 and 6 in the remainders. Site of recurrence were local in 3, regional in 3, para-aortic node in 2, distant metastasis in 6 (Lung: 4, liver: 1, brain: 1), and peritoneal dissemination in 1, including one patient who experienced simultaneous local recurrence and distant metastasis. All 3 patients who developed regional recurrence had recurred at the internal iliac node or obturator node medial to contoured vessels. No marginal recurrence occurred just outside the CTV. Overall survival at 5 years for patients with 0-1 and 2 or more nodal metastasis was 94% and 61%, respectively (p = 0.036). No local/regional failure could be observed which was attributable to nodal-CTV delineation.