Circulating tumor cell diagnostics for prostate cancer biomarkers

A method for detecting progression of prostate cancer to castration-resistant prostate cancer (CRPC) in a patient comprising (a) performing a direct analysis comprising immunofluorescent staining and morphological characterization of nucleated cells in a blood sample obtained from the patient to detect morphological and protein biomarkers of circulating tumor cells (CTC), wherein the CTCs are present among the nucleated cells subjected to the direct analysis at a frequency of less than 1 in 1,000 nucleated cells;

• (b) determining prevalence of a CTC subpopulation associated with CRPC comprising detecting a measurable feature of each of the biomarkers, wherein determining prevalence of the CTC subpopulation associated with CRPC comprises determining the prevalence of CTCs that have a nuclear size less than 67 μm2, and wherein the presence of the CTC subpopulation associated with CRPC is indicative of CRPC, (c) repeating steps (a) and (b), wherein an increase in the prevalence of the presence of the CTC population associated with CRPC indicates progression of prostate cancer to CRPC;
• and (d) treating the patient with either (i) androgen deprivation therapy (ADT) if the prevalence has not increased, or (ii) a cancer therapy other than ADT if the prevalence has increased.