Elevated TNF-α/TNFR1 and TNF-α/TNFR2 ratios indicate a decline in disease activity after 131I therapy, which is more pronounced in PTC than in PTC + AIT, suggesting that suppression of TNFR1 and TNFR2 or increased production of TNF-α is required to initiate remission of cancer. The gene discussed is TNFRSF1B; the disease is cancer.