Radiation therapy for cervix carcinoma: benefits of individualized dosimetry

This study is a presentation of the prospective collection of data on patients treated by radical radiotherapy at Westmead Hospital between December 1989 and December 1998. The impact of the routine use of individualized dosimetry and lower brachytherapy dose on patients was examined, by comparing the historical series of patients treated between 1989 to 1991 to the later patients treated with inividualised dosimetry. There were 163 patients treated with external beam and intracavitary radiotherapy during this period. Histology was squamous carcinoma in 80% (132 patients), adenocarcinoma in 13% (22 patients), and adenosquamous carcinoma in 6% (9 patients). Patients were generally treated with 50 Gy in 25 fractions to the pelvis followed by 1 low dose rate caesium intracavitary brachytherapy insertion. Patients who had dosimetry generally received 20 Gy to point A via the insertion compared to 30 Gy in the non-dosimetry group. Median follow-up was 62 months. Only 22% (18) of patients failed with disease outside the pelvis. Pelvic control was similar in the patients who had dosimetry as opposed to no dosimetry (P=0.8). In the dosimetry group there were less grade III or higher bowel toxicity (P=0.01) and less vaginal fistulae (P=0.03). The actuarial two-year survival was 56.2% in the no dosimetry group and 68.6% in the dosimetry group. When controlled for stage and performance status patients who had dosimetry had a statistically significant greater overall survival (P=0.02). Thus we found that the routine use of dosimetry was associated with a lower brachytherapy dose, decreased complications, without any decrease in local control or survival.