Patterns of brachytherapy practice for patients with carcinoma of the cervix (1996–1999): A Patterns of Care Study

Abstract

To analyze the details of brachytherapy practice in patients treated for carcinoma of the cervix in the United States between 1996 and 1999. Radiation facilities were selected from a stratified random sample. Patients were randomly selected from lists of eligible patients treated at each facility. A total of 442 patients' records were reviewed in 59 facilities to obtain data about patients' characteristics, evaluation, tumor extent, and treatment. National estimates were made using weights that reflected the relative contribution of each institution and of each patient within the sampled institutions. From our survey we estimate that 16,375 patients were treated in the United States during this study period. Unless otherwise specified, brachytherapy practice was based on the 408 patients who had their brachytherapy or all their treatment at the surveyed facility. A total of 91.5% of patients underwent brachytherapy at the initial treating institution; 8.5% were referred to a second site for brachytherapy. Forty-two percent of U.S. facilities referred at least some patients to a second facility for brachytherapy. Of U.S. facilities that treated < or =2 eligible patients per year, 61% referred all of their patients to a second facility for brachytherapy or treated with external RT alone; none of the U.S. facilities with larger experience (>2 eligible patients per year) referred all their patients to a second facility for brachytherapy treatment, but 28% referred some patients to an outside facility for brachytherapy. Overall, 94% of patients who completed treatment with curative intent received brachytherapy. Of these patients who had brachytherapy, 77.8%, 13.3%, and 0.9%, respectively, were treated with low-dose-rate (LDR), high-dose-rate (HDR), or a combination of HDR and LDR brachytherapy; 7.9% had interstitial brachytherapy (5.7% LDR and 1.9% HDR, 0.3% mixed). In facilities that treated >2 patients per year, 15.5% and 9.4% of brachytherapy procedures included HDR or interstitial, respectively; in facilities that treated fewer patients, 3.4% had HDR brachytherapy, and only 1.2% had interstitial brachytherapy. Patients treated with LDR intracavitary radiotherapy had one (23.5%), two (74.1%), or three (2.4%) implants. For patients treated with curative intent who completed radiation therapy with LDR intracavitary radiation therapy without hysterectomy, the median brachytherapy dose to Point A was 40.3 Gy, and the median total dose to Point A was 82.9 Gy. Patients were treated with HDR intracavitary radiation therapy using a variety of treatment schedules using 1-2 fractions (7.5%), 3-4 fractions (17.4%), 5-6 fractions (38.5%), 7-9 fractions (33.5%), or 12 fractions (3%). Fraction sizes were <500 cGy (29.5%), 500-<600 (25.2%), 600 (28.1%), >600 (8%), or unknown (9.2%). For patients treated with HDR, the median total dose to Point A (corrected for fraction size using a alpha/beta = 10) was 85.8 Gy (range: 56.2-116.1 Gy). At institutions treating <500 new patients per year, the percentage of patients receiving a brachytherapy dose <40 Gy was significantly higher than at institutions treating > or =500 new patients per year (p < 0.0001). For LDR intracavitary radiation therapy, 5.8% had neither bladder nor rectal doses recorded for any of their implants, whereas in HDR intracavitary radiation therapy, 73.4% had neither bladder nor rectal doses recorded for any of their implants. The median total duration of radiation therapy was identical for patients who had HDR or LDR intracavitary radiation therapy (57 days). For LDR at institutions treating <500 new patients per year, the percentage of patients with treatment duration >56 days was significantly greater than at institutions > or =500 new patients per year (p = 0.002). Of the patients who had LDR intracavitary radiation therapy implants, 65% were treated using tandem and shielded Fletcher-Suit-Delclos colpostats; other patients had mini ovoids (10.9%), cylinders (3.9%), Henschke (3.7%), or other/mixed applicators (16.5%). In contrast, of patients treated with HDR intracavitary radiation therapy, 68.7% had tandem and rings, 18.2% Fletcher-Suit-Delclos ovoids, 7.5% mini ovoids, 2.3% cylinders, and 3.2% other or mixed applicators. The median duration of treatment and median Point A dose were very similar for patients treated with HDR or LDR. Patients with HDR were treated using a variety of treatment schedules. Different applicator types were favored for LDR vs. HDR. Of patients treated with HDR, 73.4% had no brachytherapy bladder or rectal doses recorded, suggesting that full dosimetric calculations were performed only for the first fraction in many institutions. Facility size significantly impacted on referral to another institution for brachytherapy, brachytherapy dose, and treatment duration.