It has been hypothesized that carcinoma metastasis is initiated by a subpopulation of circulating tumor cells (CTCs) found in the blood of patients. However, although the presence of CTCs is an indicator of poor prognosis in several carcinoma entities, the existence and phenotype of metastasis-initiating cells (MICs) among CTCs has not been experimentally demonstrated. Here we developed a xenograft assay and used it to show that primary human luminal breast cancer CTCs contain MICs that give rise to bone, lung and liver metastases in mice. These MIC-containing CTC populations expressed EPCAM, CD44, CD47 and MET. In a small cohort of patients with metastases, the number of EPCAM(+)CD44(+)CD47(+)MET(+) CTCs, but not of bulk EPCAM(+) CTCs, correlated with lower overall survival and increased number of metastasic sites. These data describe functional circulating MICs and associated markers, which may aid the design of better tools to diagnose and treat metastatic breast cancer.

The main goals for urologists during the coronavirus disease 2019 (COVID-19) pandemic are to prevent their patients from getting COVID-19, protect themselves as health care professionals, and deliver optimal urology care [1]. While prioritisation strategies are being proposed [2,3], further measures are warranted for multifaceted action plans towards optimal perpetuation of urology care during the pandemic [4]. Urological telemedicine can lead to (1) fewer patient contacts, (2) lower infection rates among the staff, and (3) continuation of urological care by quarantined urologists [5]. However, the proportion of patients eligible for telemedicine, their wish to use telemedicine, and their demographic risk profile for acquiring a severe pandemic infection are unknown. In this context, we tested the potential of telemedicine in urology. We evaluated patients' eligibility for telemedicine according to the physician and examined the patients' perspective by evaluating their willingness for telemedicine.