Nadal et al. [247] expanded on these preceding studies by investigating HR status in CTCs compared to primary tumours and found that discordance was once again present, in this instance at greater proportions with respect to PgR. Perhaps their most intriguing finding however related to the observation that heterogeneity in HR status was seen within individual patients who bore both HR+ and HR− CTCs. Here, PGR is linked to neoplasm.