A single institutional experience with both high dose rate and low dose rate brachytherapy for cervical cancer

Abstract

Purpose: Intracavitary brachytherapy was converted from a low dose rate (LDR) Fletcher system to high dose rate brachytherapy (HDRB) using the ring and tandem applicator in January, 1996. This study reviews the initial tumor control rates and complications using a standardized dose and fractionation HDRB schema compared to the LDR treatment. Materials and Methods: One hundred ten consecutive patients with cervical cancer received combined external beam irradiation (EBRT) and HDRB with a ring and tandem applicator at a single institution from January, 1996 through December, 2000. One hundred seventy-two LDR patients were treated from December, 1977 to July, 1998. The FIGO stage distribution was as follows in HDRB and LDRB pts respectively: IB = 32 (29%),45(26%); IIA = 12(11%), 25(14%); IIB = 51(46%),68 (39%); IIIA=1 LDRB pt; IIIB = 14(13%),32(19%); IVA=1pt in each cohort. The majority of tumors were squamous cell histology (97/110 HDRB, 153/172 LDRB) with a mean size of 6 cm in HDRB pts and 5 cm in LDRB pts. Mean pelvic EBRT doses were 45 Gy in both groups. Ten LDRB pts (6%) and 48 HDRB pts (44%) received concurrent chemoradiation. HDRB treatments were delivered on an outpatient basis, once or twice weekly, using oral premedication or subcutaneous morphine. The tandem was inserted into a previously placed cervical sleeve. The HDRB dose fractionation was 2500 cGy in five fractions prescribed to point A. Dosimetry was optimized to limit the dose to bladder and rectal maximum points (ICRU defined) to less than 80% of the prescribed dose. LDRB treatments were given in one to two insertions with mean point A dose of 87Gy (range 45, 100). Results: All patients were able to complete outpatient HDRB as prescribed with no procedural complications. Mean treatment duration was 59 days (range 33, 432) for HDRB patients and 67 in the LDR cohort (range 28, 248). At median followup of 21 (HDRB) and 82 months (LDRB), 3 (3%) and 18 (11%) grade 3/4 toxicities have occurred in the HDRB and LDRB pts respectively. Ten (9%) HDRB patients developed locoregional recurrence at median 13 months and 24 (22%) developed distant metastases at median 13 months. Seventy-six (69 %) remain without evidence of disease at median 21 months. The control rates in the LDRB pts are as follows: 23 (13%) locoregional recurrences at median 21 months and 42 (24%) distant recurrences at median 21 months. One hundred one (59%) remain NED at median 87 months. Conclusion: Early followup indicates that this technique and fractionation schedule of HDRB is safe and results in comparable control rates when compared to LDRB at our institution.