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 (BT) practice in patients treated for carcinoma of the cervix in the USA from 1996–1999 Radiation facilities were randomly selected from two strata: those that treated <500 or ≥500 cancer patients/yr. 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 their 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 U.S. during this study period. Unless otherwise specified BT practice was based on the 408 patients who had their BT or all their treatment at the surveyed facility. 91.5% of patients underwent BT at the initial treating institution; 8.5% were referred to a second site for BT. 42% of U.S. facilities referred at least some patients to a second facility for BT. Of U.S. facilities that treated ≤2 eligible patients per year, 61% referred all of their patients to a second facility for BT or treated with external RT alone; none of the U.S facilities with larger experiences (>2 eligible pts/yr) referred all their patients to a second facility for BT treatment but 28% referred some patients to an outside facility for BT. Overall, 94% of patients who completed treatment with curative intent received BT. Of patients who had BT, 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 BT; 7.9% had interstitial BT (5.7% LDR and 1.9% HDR, 0.3% Mixed). In facilities that treated >2 pts per year, 15.5% and 9.4% of BT procedures included HDR or interstitial respectively; in facilities that treated fewer patients, 3.4% had HDR BT and only 1.2% had interstitial BT. Patients treated with LDR intracavitary radiotherapy (ICRT) had 1 (27.8%), 2 (70%) or 3 (2.2%) implants. For curative patients who completed RT with LDR ICRT without hysterectomy the median BT dose to Pt A was 4031 cGy and the median total dose to Pt A was 8288 cGy. Patients were treated with HDR ICRT using a variety of treatment schedules using 1–2 fractions (fxs) (8%), 3–4 fxs (17%), 5–6 fxs (39%), 7–9 fxs (34%), or had 12 fxs (3%); fractions sizes were <500 (29%), 500– <600 (25%), 600 (28%), >600 (8%), or unknown (9%). For patients treated with HDR, the median total dose to Pt A (corrected for fraction size using an α/β = 10) was 8580 cGy (5617–11606). At institutions treating <500 pts/yr, the % of patients receiving a BT dose <40 Gy was statistically higher than at institutions treating≥500 pts/yr (p < 0.0001). For LDR ICRT, 7.4% had no bladder and rectal doses recorded for all their implants, whereas in HDR ICRT, 75% had no bladder and rectal doses recorded for all their implants. The median total duration of RT was identical for patients who had HDR or LDR ICRT (57 days). For LDR at institutions treating <500 pts/yr, the % of patients with treatment duration >56 days was significantly greater than at institutions ≥500 pts/yr (p = 0.0002). Of the patients who had LDR ICRT implants, 65% were treated using tandem and shielded FSD colpostats; other patients had mini ovoids (11%), cylinders (4%), Henschke (4%), or mixed applicators (15%). In contrast, of patients treated with HDR ICRT, 69% had tandem and rings, 18% FSD ovoids, 8% mini ovoids, and 6% other or mixed applicators. The median duration of treatment and median Pt 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. 75% of patients treated with HDR had no BT bladder or rectal doses recorded, suggesting that full dosimetric calculations were only performed for the first fraction in many institutions. Facility size significantly impacted on referral to another institution for BT, BT dose, and treatment duration