ESTRO 2020 Abstract Book

S297 ESTRO 2020

Purpose or Objective To explore the factors that affect OS in patients with non- metastatic rectal cancer using the National Cancer Database (NCDB). Material and Methods The NCDB rectal cancer database was queried for patients with Stage I-III (per AJCC 7 th edition) adenocarcinoma or squamous cell carcinoma treated with radiotherapy and surgery with or without chemotherapy. Patients with missing demographic or tumor data were excluded. The following factors where analyzed to assess their significance in regards to overall survival (OS): facility type (community, comprehensive, academic, integrated cancer center), sex, age (≤50, 51-60, 61-70, >70), Hispanic vs non- Hispanic, insurance status (none, private, medicaid, medicare, other government insurance), median income quartiles (<$38000, $38000-47999, $48000-62999, ≥$63000), Charlson/Deyo score (CDCC, 0-3), grade (1-3), TNM stage, tumor size, number of regional nodes positive, lymphovascular invasion status (LVSI), days from diagnosis to definitive surgery, elapsed days between start and end of radiation, chemotherapy (none, single-agent, multiple- agent, unknown), number of regional node examined, total radiation dose (44-45, 45-50, 50.4-54, >54 Gy). Cox regression model was used for multivariate analysis, and p-values and/or hazard ratio (HR) with 95% confidence interval is presented. Results 14,367 patients in the NCDB database diagnosed between 2010-2015 met the inclusion criteria. Compared to community cancer centers, patients treated at academic cancer centers had a significantly better OS (HR=0.69[0.59-0.81]). Other factors associated with better OS were median income in the top two quartiles (HR=0.84[0.73-0.96] for quartile 3 & HR=0.83[0.72-0.95] for quartile 4), female gender (HR=0.78[0.71-0.86]), combination chemotherapy compared to no chemotherapy (HR=0.52[0.37, 0.73]), younger age (Table) and 15 more lymph nodes examine compared to those with fewer than 15 lymph nodes (HR=0.82[0.74-0.90]). Moreover, a total radiation dose of 45-50.4 Gy (HR=0.79[0.70-0.89]) was superior to doses of 44-45 Gy, but further escalation in dose above 50.4 Gy was not significantly better. Tumor characteristics found to be associated with worse OS were grade 3 (HR=1.71[1.41-2.08]), T4 tumor stage (HR=1.87[1.42-2.45]), N2 nodal stage (HR=1.88[1.29- 2.75]), N3 nodal stages (HR=1.20[1.02-1.41]), presence of LVSI (HR=1.59[1.42, 1.79]), number of positive lymph nodes (p<0.0001), number of days between diagnosis and start of treatment (p<0.0001). Conclusion We found that OS is better in patients who are female, treated at an academic institution, come from higher- income families, had 15 or more lymph nodes examined, treated with radiation of 45-50.4 Gy and multi-agent chemotherapy. OS is worse with increasing age at diagnosis, increasing CDCC score, grade 3, T4 tumor stage, N2/N3 nodal stage, presence of LVSI, larger number of positive lymph nodes, increasing number of days between diagnosis and start of treatment.

shown in the table 1. Ten patients (37%) had stage II disease and 16 (59%) stage III. Five patients experienced grade 3–4 HT,19% versus 58% of historical results; 14 (59%) patients had ≥G2 HT and 13 (48%) patients ≤G1 HT. None of the patients showed grade 3-4 thrombocytopenia. Figure 1 shows trends of hematologic parameters over the 8 weeks from the start of CRT. A total of 66% of patients had G0-G1 gastroenteric toxicity and 78% had urogenital toxicity

Conclusion PET-guided BM sparing IMRT was able to reduce acute HT in anal cancer patients treated with CRT. These results prompted us to conclude the second part of this prospective phase II trial. PD-0537 Factors Affecting Overall Survival in Non- Metastatic Rectal Cancer: An NCDB analysis P. Shaikh 1 , B. Altoos 2 , P. Renz 3 , M. Wu 4 , G. Jacobson 3 , S. Lu 5 1 West Virginia University, Radiation Oncology, Kentwood, USA ; 2 Loyola University, Radiation Oncology, Chicago, USA ; 3 West Virginia University, Radiation Oncology, Morgantown, USA ; 4 Loyola University, Research Methodology, Chicago, USA ; 5 State University of New York at Binghamton, Department of Industrial and Systems Engineering, Binghamton, USA