EP976 - The Impact of Short-Course Radiation Therapy on Textbook Oncologic Outcomes in Locally Advanced Rectal Cancer

Image or Table (Do Not add text here):

Purpose/Background: Textbook outcomes were designed as a hospital quality metric to provide patients, payers and providers with a single measure identifying patients for which all desired outcomes were obtained. Applying the concept of textbook outcomes to cancer treatment (textbook oncological outcomes, TOO) has been associated with improved long-term outcomes, however previous studies of TOO in rectal cancer have found that achieving TOO is uncommon. No significant differences in toxicities, positive resection margins, and overall survival have been noted with the neoadjuvant use of short course radiation therapy (SC-RT) or long course chemoradiation therapy (LC-RT) for the treatment of locally advanced rectal cancer (LARC), however, no previous studies have evaluated their respective effects on the achievement of TOO. Therefore, the purpose of this study was to evaluate the achievement of TOO according to the receipt of either SC-RT or LC-RT in the treatment of LARC.

Methods/Interventions: A retrospective cohort study of patients who underwent neoadjuvant chemoradiation and proctectomy for stage II or III rectal adenocarcinoma (LARC), over a 4-year period (2018-2021) in the National Cancer Database (NCDB), was performed. Patients were identified as having received SC-RT (defined as a total of 25 Gy in 5 fractions) or LC-RT (45-60 Gy given over 5-6 weeks). A textbook oncological outcome (TOO) was defined as meeting all the following criteria: no mortality within 90 days of surgery, achievement of an R0 section, ≥12 lymph nodes evaluated, length of stay (LOS) < 75th percentile for year, no readmission within 30 days of surgery, and having guideline concordant therapy (chemotherapy, either neoadjuvant or adjuvant) and a negative circumferential resection margin (CRM). Univariate and multivariate analyses were performed to determine the effect of SC-RT/LC-RT on TOO achievement.

Results/Outcomes: A total of 10,231 patients were identified with a median age of 59yrs(IQR51,68). The majority were white (8,617;84.2) and male (6,378;62.3%). Only 1,274(12.5%) underwent SC-RT for LARC. TOO was achieved in 2,048 (20.0%). Of the criteria defining TOO, no 90-day mortality (10,145;99.2%), ≥12 lymph nodes evaluated (8,130;79.5%), an R0 resection (9,565;93.5%), no 30-day readmission (9,583;93.7%), and having guideline concordant therapy (9,887;96.6%) were commonly achieved individually. A negative/non-threatened circumferential was the least achieved (3,513;34.3%). Female sex (40.5% vs. 37.0%;p=0.003) and patients with private insurance (59.9%;p < 0.001) were significantly likely to achieve TOO. The approach to radiation was not associated with achievement of TOO on univariate analysis (SC-RT 232, 18.2% vs. LC-RT 1816, 20.2%; p=0.09) or multivariate analysis (OR 0.90, 95%CI 0.77-1.06).

Conclusion/Discussion: TOO in the treatment of LARC is difficult to achieve. Based on this analysis, the choice of SC-RT or LC-RT does not have an impact on achievement of TOO. Importantly, SC-RT may be utilized as important option for patients with barriers to accessing healthcare without compromising outcomes.