Trends in IMRT Utilization for Definitive Treatment of Cervical Cancer, 2004-2018

Abstract

<h3>Purpose/Objective(s)</h3> Intensity-modulated radiation therapy (IMRT) is an advanced radiotherapy technique that delivers conformal radiation to desired targets while minimizing dose to surrounding organs at risk. In the post-operative setting, IMRT is associated with reduced acute and late genitourinary and gastrointestinal side effects for patients with cervical cancer. However, no prospective randomized data exist for the use of IMRT in the setting of definitive treatment of intact cervical cancer. The objective of this study was to identify trends in IMRT use for this population. <h3>Materials/Methods</h3> Patients with stage IB2-IVA cervical cancer diagnosed from 2004-2018 who were treated with curative intent chemoradiation were identified in the National Cancer Database. Patients who underwent primary surgical management, did not receive external beam radiation to the pelvis or received radiation outside the pelvis, or received an unspecified technique or target of radiation were excluded. The primary outcome of interest was utilization of IMRT vs 3D conformal radiotherapy (3D-CRT) over time. A Cochrane-Armitage test was performed to assess trends over time. T-tests, chi-square tests, and multivariable logistic regression with propensity score matching were used to identify factors associated with receipt of IMRT. <h3>Results</h3> Overall, 13,974 patients met inclusion criteria; 4,590 (33%) received IMRT, and 9,384 (67%) received 3DCRT. In this cohort, 65% were non-Hispanic White, 45% were early stage (I-II), 80% were squamous histology, 62% received brachytherapy, and 28% had lymph node involvement. The utilization of IMRT increased from 30% in 2004 to 71% in 2018 (p<0.001). After adjustment for clinical and demographic variables, factors associated with IMRT use were: Hispanic ethnicity (adjusted odds ratio [aOR] 1.2, 95% confidence interval [CI] 1.0-1.5), treatment in the Western U.S. (aOR 1.4, CI 1.2-1.7) and the Southern U.S. (aOR 1.3, CI 1.1-1.5), living more than 50 miles from the treatment facility (aOR 1.2, CI 1.0-1.5), stage III disease (aOR 1.3, CI 1.1-1.5), and lymph node involvement (aOR 1.4, CI 1.3-1.6). Compared to an academic medical center, patients receiving care at a comprehensive community cancer center were less likely to receive IMRT (aOR 0.66, CI 0.59-0.72). There were no differences in IMRT use by age, insurance, or medical comorbidities. <h3>Conclusion</h3> Despite the lack of prospective efficacy data supporting the use of IMRT in patients with intact cervical cancer, IMRT has dramatically increased over the last fifteen years especially for patients with advanced-stage disease or lymph node involvement. More data on the optimal use of IMRT, including appropriate target volume margins and on-board imaging, are needed.