Disease progression
We considered two main factors affecting the tumor growth rate and the
recurrence rate:
(1) Patient age 16: The growth rate of the
primary tumor was estimated to be 0.0091 (range 0.0082-0.01) for
patients aged 40-59 years old and 0.004 (range 0.0036-0.0044) for
patients more than 60 years old. The rate of locoregional progression
during AS was 0.0023 (range 0.0021-0.0025) and 0.0005 (range
0.00045-0.00055) for patients aged 40–59 years and more than 60 years
old respectively. The recurrence rate after HT was estimated to be 0.004
(range 0.003-0.005) independent from age.14
(2) BRAFV600Estatus 10: To calculate the recurrence rate following
HT in patients with lrPTMC who are positive toBRAFV600E mutation we used the Kaplan-Meier
curves for disease recurrence-free survival for a patient with low-risk
conventional PTMC and BRAFV600E as presented by
Kim et al.10 We digitized the curves using GetData
Software and fit the data to an exponential distribution, estimating the
recurrence rate of BRAFV600E mutation-positive
and BRAFV600E mutation-negative, respectively.
We then calculated the hazard ratio (HR) of recurrence-free survival
between the BRAFV600E mutation-positive andBRAFV600E mutation-negative patients. We
assumed the same HR also for the tumor growth rate and the rate of
progression to loco-regional disease. Lastly, we assumed that the
patient BRAFV600E status is known.