The human Sept4/Bradeion GTPase (56Kda) is specifically expressed in colorectal cancer, malignant
melanoma, prostate cancer and other urologic cancers such as renal cell carcinoma and bladder cancer. Significance of
Bradeion is that, 1) 'all or none' expression, 2) no genetic alterations among patients, and 3) strong tissue-and cell typespecificity.
This character satisfies the desired criteria as a target to monitor and control cancer. With the advent of current
technology development in nano-scale, we have succeeded to develop the effective serum test for early diagnosis of
cancer. Fluorescence correlation spectroscopy (FCS) can directly and quickly analyse protein-protein binding in a sample
solution by reflecting the molecular weight of the labeled molecules. We present a novel and successful diagnostic
methods by the quantitative detection of Sept4/Bradeion β in the patients' serum using monoclonal antibodies. The
resulting diagnostic efficacy was as follows; 100% (colorectal cancer), 89.0 % (prostate cancer), 92.3 % (renal cell
carcinoma), and 89.0 % (bladder cancer). More importantly, the increased Bradeion titers decreased to the normal level
after one week (polypectomy with colonoscope) to 3 weeks after surgical detection of the cancer.