Prostate cancer (PCa) is the most common malignancy and the second leading cause of cancer death in American men. Due to the lack of accurate tests to distinguish aggressive cancer from indolent tumor, prostate cancer is often over-treated. Post-surgery pathology analysis revealed that 30% of tumors removed by radical prostatectomy are deemed clinically insignificant and would not have required such invasive treatment.^1^ Over-diagnosis and treatment of low-risk prostate cancer has serious and long-lasting side effect: as high as 70% of the patients who receive radical prostatectomy treatment will suffer a loss of sexual potency that cannot be remedied by drugs such as sildenafil citrate.^2^ We herein report a simple nanoparticle-serum protein adsorption test that not only can distinguish prostate cancer from normal and benign conditions, but also is capable of predicting the aggressiveness of prostate cancer quantitatively. This new test could potentially deliver the long-expected and very much needed solution for better individualization of prostate cancer treatment
