To Fracture Not—Sustained Benefits of Intensity Modulated Radiation Therapy (IMRT) in Pelvic Malignancies

Short-course preoperative radiotherapy increases pelvic fracture risk in rectal cancer

Introduction

Pelvic insufficiency fractures (PIFs) are adverse events associated with chemoradiotherapy (CRT) administered preoperatively in rectal cancer, with incidences of 0-33.6% reported in the literature. Data on PIFs after 5 × 5 Gy fractionated short-course radiotherapy (SCRT) using highly conformal radiotherapy techniques such as volumetric modulated arc therapy (VMAT) is limited.

Methods

The Turku University Hospital colorectal cancer database was searched for patients operated on for stage I-III rectal cancer during the years 2014-2018. The hospital's routine follow-up includes a 2-year computed tomography (CT) scan, which was systemically re-evaluated to detect PIFs. Only radiotherapy delivered using VMAT and image-guided approaches was included. Baseline demographics, tumor data, and dose-volume data were collected to identify risk factors for PIFs.

Results

Median time to CT scan was 24 months. Among the 164 patients analyzed, the 2-year PIF incidence was 22.2% for SCRT (n = 12/54, OR 9.1 (CI95% 1.9-42.9), p = 0.004), 9.1% for CRT (n = 4/44, OR 3.2 (CI95% 0.6-18.3), p = 0.13) and 3.0% (n = 2/66, reference) for those operated on without radiotherapy. The PIF incidence was not explained by differences in dose-volume data in either the SCRT or CRT groups. Fracture risk was higher in women, up to 50% after SCRT.

Conclusions

Every fifth patient treated with SCRT and rectal surgery presented with a PIF. Critical bony structures to be avoided during radiotherapy contouring could not be identified. Clinicians, especially those involved with the follow-up of rectal cancer, should be aware of this potentially debilitating and surprisingly common adverse event.

Racial and Ethnic Health Disparities in Delay to Initiation of Intensity-Modulated Radiotherapy

PURPOSE

Delays in initiation of radiotherapy may contribute to inferior oncologic outcomes that are more commonly observed in minoritized populations in the United States. We aimed to examine inequities associated with delayed initiation of intensity-modulated radiotherapy (IMRT).

MATERIALS AND METHODS

The National Cancer Database was queried to identify the 10 cancer sites most commonly treated with IMRT. Interval to initiation of treatment (IIT) was broken into quartiles for each disease site, with the 4th quartile classified as delayed. Multivariable logistic regression for delayed IIT was performed for each disease site using clinical and demographic covariates. Differences in magnitude of delay between subsets of patients stratified by race and insurance status were evaluated using two-sample t-tests.

RESULTS

Among patients (n = 350,425) treated with IMRT between 2004 and 2017, non-Hispanic Black (NHB), Hispanic, and Asian patients were significantly more likely to have delayed IIT with IMRT for nearly all disease sites compared with non-Hispanic White (NHW) patients. NHB, Hispanic, and Asian patients had significantly longer median IIT than NHW patients (NHB 87 days, P < .01; Hispanic 76 days, P < .01; Asian 74 days, P < .01; and NHW 67 days). NHW, Hispanic, and Asian patients with private insurance had shorter median IIT than those with Medicare (P < .01); however, NHB patients with private insurance had longer IIT than those with Medicare (P < .01).

CONCLUSION

Delays in initiation of IMRT in NHB, Hispanic, and Asian patients may contribute to the known differences in cancer outcomes and warrant further investigation, particularly to further clarify the role of different insurance policies in delays in advanced modality radiotherapy.

Worsening racial disparities in utilization of intensity modulated radiotherapy

Purpose

The benefits of intensity modulated radiation therapy (IMRT) compared with standard 3-dimensional conformal radiation therapy have been demonstrated in many cancer sites and include decreased acute and late toxicity, improved quality of life, and opportunities for dose escalation. Limited literature suggests non-white patients may have lower utilization of IMRT. We hypothesized that as the use of IMRT has increased in recent years, racial inequities have persisted and disproportionately affect non-Hispanic Black (NHB) patients. We aim to evaluate temporal trends in IMRT utilization focusing on disparities among minoritized populations.

Methods and Materials

The National Cancer Database was queried to identify the 10 disease sites with the highest total number of cancer patients treated with definitive intent IMRT in 2017, the most recent year for which data are available. Exclusions included stage IV, age <18 years, unknown insurance status, unknown race, and palliative intent radiation. Race and ethnicity variables were combined and classified as non-Hispanic White, Hispanic, NHB, Asian, Native American/Eskimo, and Hawaiian/Pacific Islander. Multivariable logistic regression for IMRT utilization was performed for each disease site for both early (2004-2010) and contemporary (2011-2017) cohorts, adjusting for clinical and demographic covariates.

Results

Among the 10 selected disease sites, 1,010,292 patients received radiation therapy as part of definitive treatment between 2004 and 2017. Overall IMRT utilization rates increased from 22.0% in 2004 to 57.8% in 2017. After adjustment and compared with non-Hispanic White patients, NHB patients were significantly less likely to receive IMRT in 1 of 10 disease sites in the 2004 to 2010 cohort, and 5 of 10 disease sites in the 2011 to 2017 cohort.

Conclusions

Despite greater awareness of racial disparities in cancer care and outcomes, this study demonstrates worsening disparities in the use of IMRT, particularly for NHB patients. These differences may exacerbate racial disparities in cancer outcomes; therefore, identification of underlying drivers of differential IMRT utilization is warranted.