Use of small pelvic field instead of whole pelvic field in postoperative radiotherapy for node-negative, high-risk stages I and II cervical squamous cell carcinoma.

We investigated whether a small pelvic (SP) field that covers primarily the pericervical regions in postoperative radiotherapy for cervical squamous cell carcinoma is adequate for a subgroup of node-negative patients. Of 84 patients with stage I-II disease treated with postoperative radiotherapy due to pathologic risk factors, 42 node-negative patients received SP-field radiotherapy, whereas remaining 42 node-positive patients were treated with a conventional whole pelvic (WP) field that also covered pelvic lymph nodes, both with 50.0-50.4 Gy/25-28 fractions. The pathologic risk factors included positive nodes, deep stromal invasion (>/=2 /3 thickness), parametrial extension, and positive or close surgical margin. Recurrence was identified for 20 patients: three in the SP group and 17 in the WP group. Intrapelvic recurrence accounted for all three recurrences in the SP group and for four in the WP group; 5-year pelvic-control rate did not differ significantly between the SP (93%) and WP (90%) groups. Extrapelvic recurrence (n = 11) was identified exclusively in the WP group. Patterns of recurrence indicate that use of an SP field instead of a WP field may be adequate in postoperative radiotherapy for a subgroup of node-negative, high-risk patients.