3438 - Learning From Failure: A Multifactorial Analysis Of Locoregionally Advanced Laryngeal Cancer(Lalc) Recurrence And The Impact Of A Standardized Sop In A Resource-Limited Setting

Purpose/Objective(s): In low- and middle-income countries (LMICs), LALC prognosis is often compromised by treatment heterogeneity. This study aimed to stratify predictors of early versus late radiotherapy (RT) failure and evaluate the efficacy of a newly implemented Institutional Standard Operating Procedure (SOP) on survival outcomes.

Materials/Methods: This two-phase study was conducted at a tertiary center. Phase I (Retrospective): A cohort of 1,000 patients (2016–2020) was reviewed. Failures were stratified by timing: Early (<12 months) vs. Late (>12 months). Univariate and multivariate Cox proportional hazards regression models were utilized to identify independent predictors of recurrence. Phase II (Prospective): Based on Phase I findings, a standardized SOP was implemented (2020–2021) for 100 Stage III/IV patients, prioritizing precise target delineation,stringent monitoring of set up error with adaptive replanning,implementation of radionomics with dose escalation and strict nutritional support. Primary endpoints were Recurrence-Free Survival (RFS) and 3-Year Overall Survival (3YOS), calculated using Kaplan-Meier analysis.

Results: Phase I: Recurrence occurred in 20% (200/1,000) of the historical cohort. Failures were predominantly Early (n=165; 82.5%), characterized by local failure (73%). Multivariate analysis identified geographical miss (HR >1.5; p<0.05), low RT dose, and poor nutrition as independent predictors of early failure. Late recurrences (n=35; 17.5%) were driven by inadequate chemotherapy dose and aggressive tumor biology.

Phase II: Following SOP implementation (n=100), the total recurrence rate dropped to 12% at 4 years. Of the 12 failures, 8 occurred within 1 year and 4 between 12–18 months. The 4-year Recurrence-Free Survival (RFS) was 88%. Total mortality was 11% (7 cancer-related, 4 non-malignant), resulting in a 3-Year Overall Survival (3YOS) of approximately 89%. This represents a statistically significant improvement in disease control compared to historical controls.

Conclusion: Historical analysis reveals distinct failure patterns: early recurrence is driven by technical and nutritional factors, while late recurrence is associated with systemic therapy inadequacy. Implementation of a targeted SOP addressing these specific vulnerabilities successfully improved RFS to 88% and OS to 89%, validating this protocol as a feasible standard of care for resource-limited settings.