NR4A1 and neoplasm: Similarly, the hormonal status of DTCs and CTCs could be completely different from that of the primary tumor, which on the one hand (tumor-negative, DTC/CTC-positive) could increase the number of patients eligible for endocrine therapy and on the other (tumor-positive, DTC/CTC-negative) could explain why endocrine therapy fails in a subset of hormone receptor-positive patients.