Intensity-modulated whole pelvic radiotherapy in women with gynecologic malignancies

Abstract

Purpose: To describe our initial clinical experience with intensity-modulated whole pelvic radiotherapy (IM-WPRT) in women with gynecologic malignancies. Methods and Materials: Between February 2000 and August 2001, 40 gynecology patients underwent IM-WPRT. After fabrication of customized immobilization, all patients underwent contrast-enhanced CT, and a clinical target volume was contoured consisting of the upper vagina, parametria, uterus (if present), and presacral and pelvic lymph node regions. The clinical target volume was expanded by 1 cm to create a planning target volume (PTV). Using commercially available software, 7- or 9-field, 6-MV, coplanar IM-WPRT plans were generated for all patients. The worst acute gastrointestinal and genitourinary toxicity during treatment was scored on a 4-point scale: 0, none; 1, mild, no medications required; 2, moderate, medications required; and 3, severe, treatment breaks or cessation, hospitalization. As a comparison, acute toxicities in 35 previously treated conventional WPRT patients were analyzed. No significant differences were noted in the clinicopathologic and treatment factors between the two groups. Results: IM-WPRT plans provided excellent PTV coverage, with considerable sparing of the surrounding normal tissues. On average, 98.1% of the PTV received the prescription dose. The average percentage of the PTV receiving 110% and 115% of the prescription dose was 9.8% and 0.2%, respectively. IM-WPRT was well tolerated, with no patient developing Grade 3 toxicity. Grade 2 acute gastrointestinal toxicity was less common in the IM-WPRT group (60 vs. 91%, p = 0.002) than in the conventional WPRT group. Moreover, the percentage of IM-WPRT and WPRT patients requiring no or only infrequent antidiarrheal medications was 75% and 34%, respectively ( p = 0.001). Although less Grade 2 genitourinary toxicity was seen in the IM-WPRT group (10% vs. 20%), this difference was not statistically significant ( p = 0.22). Conclusion: IM-WPRT is a promising approach in gynecology patients. IMRT planning resulted in excellent PTV coverage, with considerable sparing of normal tissues. Treatment was well tolerated and associated with less acute gastrointestinal sequelae than conventional WPRT. Longer follow-up and more patients are needed, however, to evaluate the full merits of this novel approach.