Course and predictors of excellent response to therapy in patients with differentiated thyroid cancer at long-term follow-up

Objectives: To investigate the long-term outcomes of differentiated thyroid cancer (DTC) and the predictive factors for excellent and incomplete responses to therapy on long-term follow-up of patients.

Methods: A retrospective chart review and analysis was carried out at King Abdulaziz University Hospital, Jeddah, Saudi Arabia. Demographic, histological, and therapeutic data were collected from patients older than 13 years at the time of diagnosis, with a minimum follow-up of 18 months. Outcomes were divided into excellent, indeterminate, biochemically incomplete, and structurally incomplete responses. Odds ratios (ORs) for predictors of incomplete response at the last visit were determined. We first tested associations univariately with incomplete responses, and then variables with significant associations were included in a multivariable logistic model.

Results: Among 230 patients with DTC, 61.7% had excellent responses to therapy on long-term follow-up, and 24.3% had incomplete biochemical and structural responses. The median follow-up was 4.6 years. Factors significantly associated with incomplete response to therapy in the multivariate analysis (p<0.05) were age >55 years (OR=5) and lymph node (OR=3.4) and distant metastases (OR=29). Older age did not affect the outcome in low-risk patients with DTC but was significantly associated with incomplete responses in those with intermediate risk (p=0.04) and high risk (p=0.003).

Conclusion: We strongly advocate incorporating age into recurrence risk assessment for patients with DTC.