More Aggressive Cancer Behaviour in Thyroid Cancer Patients in the Post-COVID-19 Pandemic Era: A Retrospective Study

PURPOSE: Many thyroid cancer patients have suffered from treatment delays caused by the coronavirus disease 2019 pandemic. Although there have been many reviews, recommendations, or clinical experiences, clinical evidence that evaluates patient disease status is lacking. The aim of our research was to evaluate thyroid cancer behaviour in the post-COVID-19 era. PATIENTS AND METHODS: A retrospective study was conducted and thyroid cancer patient data from February 1, 2017 to September 15, 2020 were pooled for analysis. The demographic, ultrasound and pathological data of the pre- and post-COVID-19 groups were compared. Lymph node metastases, tumour size, extrathyroidal extension, and multifocality were compared year-by-year to evaluate annual changes in patient characteristics. Regression analyses were adopted to reveal cancer behaviour along with the admission date interval and to reveal risk factors for lymph node metastasis. Patient ultrasound data were compared before and after the lockdown to assess tumour progression. The outcomes of delays in treatment ≤180 days were then studied. RESULTS: The post-lockdown patients were more likely to have multiple lesions (31.2% vs 36.5%, p = 0.040), extrathyroidal extension (65.5% vs 72.2%, p = 0.011) and lymph node metastases (37.7% vs 45.0%, p = 0.007), while tumour size remained stable (1.01cm vs.1.02cm, p = 0.758). The lymph node metastasis rate increased by year (p < 0.001). The tumour size correlated negatively with the post-lockdown admission date (p = 0.002). No significant difference in tumour size, multifocality or lymph node metastasis on ultrasound was revealed between the pre- and post-lockdown group. No significant difference in tumour size, multifocality, extrathyroidal extension or lymph node metastasis was revealed among patients with a delayed treatment time ≤180 days. CONCLUSION: Patients with a COVID-19-induced treatment delay had more aggressive cancer behaviour. Rebound medical visits and annually increasing aggressiveness may be potential reasons for this observation, as individual patient tumour did not progress during the delay.