1073 - Comprehensive Geriatric Assessment Guided Radiotherapy in Older Patients with Locally Advanced Rectal Cancer - Results of a Multicenter Prospective Non-Operative Cohort Study

Y. Yang¹, W. Liu Jr², Y. Tang², J. Wang³, S. Wang², Y. LI², X. Wang⁴, and J. Jin^1,2; ¹Department of Radiation Oncology , National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital and Shenzhen Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shenzhen, China, ²Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China, ³Department of Radiation Oncology, the Fourth Hospital of Hebei Medical University, Shijiazhuang, China, ⁴Department of Colorectal Surgery, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical Colleg, Beijing, China

Purpose/Objective(s): Chemoradiotherapy (CRT) is the main treatment for elderly patients with non-metastatic rectal cancer who are ineligible for or decline surgery, but the optimal modality remains unclear. This study was to validate the safety and efficacy of comprehensive geriatric assessment (CGA) guided radiotherapy in older patients. Materials/

Methods: A prospective non-operative cohort from a single-arm, multicenter, phase II trial, patients aged over 70 and diagnosed with rectal cancer were enrolled and evaluated by CGA. CGA guided radiotherapy or concurrent chemotherapy were individually conducted in a multidisciplinary setting. Patients in fit, intermediate and frail group were scheduled to receive standard neoadjuvant CRT, LCRT and SCRT alone respectively. The treatment results of patients who were unfit for or refused surgery were analyzed. The Kruskal-Wallis test and Fisher test were applied to assess the baseline characteristics and compliance, while Kaplan-Meier method and competing risk regression were used to calculate survival rates and correlation analyses. A P-value <0.05 was considered statistically significant.
Results: In a total of 109 patients evaluated by CGA, forty-seven individuals who did not undergo surgery were included, with twenty-six, nine and twelve categorized into fit, intermediate and frail groups. Long-course radiotherapy (LCRT) was delivered to 24 (92.3%) and 8 (88.9%) patients in fit and intermediate groups, while all the frail patients received short-course radiotherapy (SCRT) (P <0.001). Only 11 (23.4%) grade 3 or above toxicities were observed overall, while hematologic adverse effects occurred more often in the fit group (P=0.029), probably attributed to different CRT modalities. Within a median follow-up time of 69.0 months, the 4-year overall survival (OS), progression-free survival (PFS) and cancer-specific survival (CSS), Loco-regional Free Survival (LCFS) rates were 19.9% (95% CI: 11.2%-35.7%), 17.0% (95% CI: 9.1%-32.0%), 41.4% (95%CI: 27.1%-63.0%) and 43.6% (95%CI: 28.0%-67.8%) in total, with no significant difference among the three subgroups. SCRT (HR=0.00, 95% CI: 0.00-0.04, P<0.001) and dose boost to tumor (HR=0.10, 95% C: 0.01, 0.95, P=0.045) contributed to lower tumor-related death rates in multiple competing risk regression.
Conclusion: Radiotherapy guided by CGA was effective and well-tolerated in non-surgical elderly patients with rectal cancer. The frail cohort treated with SCRT alone seemed to have achieved similar clinical outcomes as the fit group who received CRT, indicating that the application of SCRT warranted further investigation in a larger population of elderly patients.