Objective: The aim of this study was to assess clinically the adequacy of vessel-contouring-based pelvic radiotherapy with regard to nodal coverage for uterine cervical cancer.
Methods: Fifty patients with Stages I-III cervical cancer, treated with vessel-contouring-based three-dimensional radiotherapy since August 2002, were entered into the study (median age: 54, 47 received concurrent daily cisplatin). All patients were treated with external beam radiotherapy using a four-field box technique with or without brachytherapy. Pelvic blood vessels were identified and contoured on computed tomography simulation images. A generous margin was set outside these vessels outlined on digitally reconstructed radiograph accounting for normal size lymph nodes, patient's motion and set-up uncertainty. Multi-leaf collimator (MLC) was inserted and adjusted manually. Patterns of recurrence were clinically evaluated.
Results: Distance between major vessels and MLC edges varied inter- and intra-individually. Median distance in the mid-iliosacral joint level was 25 mm (left) and 24 mm (right). The maximum and the minimum distances ranged from 25 to 45 mm (median, 32) and 9 to 27 mm (median, 15) for left side and 24 to 41 mm (median, 30) and 7 to 28 mm (median, 15) for right side, respectively. With a median follow-up of 43 months, 10 patients developed recurrence. However, no marginal recurrence was occurred just lateral to the contoured vessels. All three patients who developed regional recurrence had recurred at the internal iliac node or the obturator node medial to contoured vessels.
Conclusions: Contoured vessels can be used as surrogate markers for location of the pelvic lymph nodes.