Pelvic nodal CTV from L4-L5 or aortic bifurcation? An audit of the patterns of regional failures in cervical cancer patients treated with pelvic radiotherapy

Abstract

OBJECTIVE: To assess the patterns of recurrence in cervical cancer patients treated with pelvic nodal clinical target volume at L4-L5 junction instead of aortic bifurcation. METHODS: Records of patients with locally advanced cervical cancer treated with chemo-radiation were reviewed. Patients treated with standard pelvic fields (superior border of the field at L4/L5 junction), without any radiological evidence of regional lymphadenopathy (<10 mm) were included in the study. The level of aortic bifurcation was retrospectively documented on computed tomography. Patterns of recurrences were correlated to the aortic bifurcation and the superior border of the radiation fields (L4/L5). RESULTS: Aortic bifurcation was above the radiation fields (above L4/5) in 82 of 116 (70.7%) patients. Of the nine patients that recurred above the radiation field, 5 (55%) were above L4/5 failures, i.e. between aortic bifurcation and L4/5, and 4 (45%) had para-aortic failures. On retrospective analysis, 16 patients were found to have subcentimeter lymph nodes and higher nodal failures (7/16) were observed in patients with subcentimeter regional lymph nodes at diagnosis. CONCLUSIONS: Superior border of nodal clinical target volume should ideally include the aortic bifurcation instead of L4-L5 inter space in patients with locally advanced cervical cancer. Radiotherapy fields need to be defined cautiously in patients with subcentimeter pelvic lymph nodes.