Circadian rhythm in prostatic acid phosphatase (PAP): a potential tumor marker rhythm in prostatic cancer (PCa)

In order to define circadian states for an earlier diagnosis and for optimal response to treatment, the possibility of a circadian rhythm in serum PAP was investigated in subjects with and without prostatic cancer. Two groups of subjects were investigated: a. 12 patients affected by PCa, further subdivided in two subgroups: 1. without metastasis (6 patients) and 2. with metastatic disease (6 patients); b. 9 age-matched healthy control subjects. Controls and PCa patients were synchronized before starting the study with standardized meal times and nocturnal rest (22(00) to 06(00) ). Venous blood samples were drawn at prearranged hours (00(00), 04(00), 08(00), 12(00), 16(00), 20(00) ) for 24 consecutive hours. Each serum sample was assayed for PAP. Data on each group and subgroup were evaluated by conventional statistical analysis and by 'single' and 'population mean cosinor' to define rhythm parameters. PCa patients, as a single group, did not show a significant circadian PAP rhythm. A statistically significant circadian PAP rhythm was however detected in the subgroup without metastasis, on the contrary no rhythm was detected in the subgroup with metastatic disease. The potential of these rhythms as marker of cancer is noted.