Annual Hazard Rate of Recurrence in Middle Eastern Papillary Thyroid Cancer over a Long-Term Follow-Up

Abstract

Predicting the pattern of recurrence in papillary thyroid cancer (PTC) is necessary to establish optimal surveillance and treatment strategies. We analyzed changes in hazard rate (HR) for tumor recurrence over time in 1201 unselected Middle Eastern PTC patients. The changes in risk were further analyzed according to clinical variables predictive of early (≤5 years) and late (>5 years) recurrence using Cox regression analysis to identify patient populations that remain at risk. Tumor recurrence was noted in 18.4% (221/1201) patients. The annualized hazard of PTC recurrence was highest during the first 5 years (2.8%), peaking between 1 and 2 years (3.7%), with a second smaller peak between 13 and 14 years (3.2%). Patients receiving radioactive iodine (RAI) therapy had lower recurrence hazard compared to those who did not (1.5% vs. 2.7%, p = 0.0001). Importantly, this difference was significant even in intermediate-risk PTC patients (0.7% vs. 2.3%; p = 0.0001). Interestingly, patients aged ≥55 years and having lymph node metastasis were at persistent risk for late recurrence. In conclusion, we confirmed the validity of the double-peaked time-varying pattern for recurrence risk in Middle Eastern PTC patients and our findings could help in formulating individualized treatment and surveillance plans.

Microscopic Extrathyroidal Extension Results in Increased Rate of Tumor Recurrence and Is an Independent Predictor of Patient’s Outcome in Middle Eastern Papillary Thyroid Carcinoma

“…Interestingly, PTC is one of the most common cancers in Saudi Arabia and is the second commonest cancer affecting Saudi females (11). Middle Eastern PTCs show a relatively higher rate of recurrence than in Western countries (12)(13)(14)(15). Therefore, identifying patients at risk of recurrence is a critical step in the management of high risk PTCs, so that appropriate treatment can be initiated.…”

Risk Factors for Central Lymph Node Metastases and Benefit of Prophylactic Central Lymph Node Dissection in Middle Eastern Patients With cN0 Papillary Thyroid Carcinoma

“…Among those who underwent PCLND, 38% (81/213) of PTC patients were found to have CLNM by histopathology post-operative result, which implies that occult metastatic lymph nodes would have remained undetected if PCLND was not performed. This is of great clinical value for PTC patients from Middle Eastern ethnicity where recurrence rate is relatively high ( 36 – 38 ). Even in this cohort, which included only cN0 PTCs, recurrence rate was 13%.…”

Survival Analysis: Where, Why, What and How?

“…Risk is the probability of occurrence of an event and is generally calculated at the end of the study irrespective of the time; whereas, the hazard rate is the risk per unit of time such as hazard of recurrence of papillary thyroid cancer per year in a high-risk population [8]. This can be different from year-toyear such as a low rate in the first year and progressively increasing each year.…”