Combined Intensity-Modulated Radiation Therapy and Brachytherapy in the Treatment of Cervical Cancer

Abstract

This treatment planning study compared pseudo-step-wedge intensity modulation (PSWIM), intensity-modulated radiation therapy (IMRT), and conventional external irradiation, all combined with brachytherapy, for treatment of patients with cervical cancer. This was a prospective study of 10 patients treated with PSWIM delivering 50.4 Gy to the pelvic lymph nodes and 20 Gy to the cervical tumor. This treatment was compared with a conventional treatment plan with a four-field box to 45 Gy and to an IMRT plan delivering 45 Gy. In each case, brachytherapy was prescribed to a total Point A low-dose-rate equivalent dose of 85 Gy. Total doses to Points A, Point P, the bladder point, and the rectal point were calculated. Acute toxicity and treatment response were prospectively recorded. The mean PSWIM total low-dose-rate equivalent dose to Points A and P (97.3 Gy and 65.1 Gy, respectively) was significantly higher, the mean rectal dose was the same, and the mean bladder dose was higher than with IMRT or four-field box. No acute toxicity of greater Grade 2, as defined by the than Radiation Therapy Oncology Group, was experienced. The positron emission tomography-based treatment response compared favorably with our institutional experience. Use of PSWIM and brachytherapy delivers significantly more dose to the tumor and lymph nodes than do competing techniques. Rectal doses are comparable. Maximum bladder point doses are higher. Toxicity and tumor response are acceptable.