Chromogranin A--serum marker for prostate cancer.

Prostate Cancer is the second most prevalent neoplasm after lung cancer in men. It commonly presents in patients with a strong family history. The measurement of Prostate Specific Antigen (PSA) in free and bound forms is one of the methods to diagnose it. It is very much useful for monitoring the therapeutic efficacy, staging, prognosis, tumour volume evaluation, detection of recurrent disease, screening and early diagnosis. Chromogranin A (CgA) is an acidic glycoprotein that is commonly expressed by neuroendocrine cells and constitutes one of the most profuse components of secretory granules. When a tumour develops in an endocrine tissue, it becomes the main source of circulating CgA. Its concentration is thought to be elevated in relation to neuroendocrine differentiation of prostate cancer. CgA is a useful predictive marker in patients with prostatic cancer who have lower PSA. It is known that neuroendocrine cells in the prostate do not contain androgen receptors and are not regulated by androgens. PSA expression was stimulated by androgen through androgen receptors, so it is suggested that cases of prostate cancer associated with low serum PSA and high serum CgA, which would have more neuroendocrine cells with less androgen receptors, may show resistance to endocrine therapy and a poor prognosis. Therefore serum CgA tends to be elevated in high grade prostate cancer cases. Hence it can be used to fill the gap if any left by PSA when combined with serum PSA, the serum marker may effectively predict the prognosis after endocrine therapy. CgA expression in prostate cancer biopsies is an independent extrapolative factor of hormone refractory disease in patients with newly diagnosed prostate cancer on early androgen deprivation therapy.