Figure 1: Tumor focus size approach from the upper range clearly separates four scenarios for pT1a tumors: (a) tumors 0.5-1.0 cm reveal almost 1:1 increase of tumor volume per diameter unit, (b) tumors 0.2-0.5 cm show about one fifth growth of tumor volume per diameter unit, (c) tumors 0.02-0.2 cm increase around 2 hundredth of tumor volume per diameter unit, and (d) tumors smaller than 0.02 cm expand about 2 ten-thousandth the tumor volume per diameter unit. This volume growth has to be coupled with number of foci, histological growth pattern (pushing vs. infiltrative), clonality pattern (homogeneous vs. heterogeneous) and simple genotyping (BRAF status) to determine the need of adjuvant therapy in multicentric PTC less than 1cm (pT1a(m)), but with particular emphasis for tumor smaller than 5 mm that are being more frequently detected due to more exhaustive histological examination. FAL = Fractional allelic loss.