In the present study we demonstrate that high expression of cell-surface TROP2 is a marker of, and plays a functional role in the ability of androgen-sensitive prostate cancer cells to recover from docetaxel-based chemotherapy, and that high TROP2 expression is a marker of poor prognosis in patients with low-grade prostate tumors. The gene discussed is TACSTD2; the disease is Familial prostate cancer.