Tumor accumulation of the HER2-TTC over time was accompanied by a decrease of thorium-227 in blood, with a tumor to blood ratio at 336 h of 17.3 ± 3.5 for the DLD-1 parental and 12.8 ± 2.4 for the DLD-1 BRCA2 -/- (Table 1). The gene discussed is BRCA2; the disease is neoplasm.