Abstract
Background: An intact immune function may be important in eliminating or maintaining minimal residual disease latent.
Objective: Use the absolute lymphocyte count as an immune biomarker, determine its association with minimal residual disease and relation with biochemical failure.
Design, setting, and participants: prospective observational single centre study in men treated by radical prostatectomy for localized prostate cancer. One month after surgery blood and bone samples were taken to detect circulating prostate cells and micro-metastasis. A total of 404 men were enrolled, at each follow up time total PSA, ALC and CPC presence/absence were determined.
Outcome measurements and statistical analysis: observed times to biochemical failure (Kaplan-Meier) and restricted mean biochemical failure free survival times were assessed, changes in the absolute lymphocyte count and the presence/absence of circulating prostate cells were determined during follow-up and association with biochemical failure.
Results and Limitations: 404 men participated; 182 were minimal residual disease negative (Group A), 80 had only micro-metastasis (Group B) and 142 were circulating prostate cell positive (Group C); 175 men underwent biochemical failure, Group C were at high risk of early failure, Group B of late failure. One month post-surgery Group C men had lower absolute lymphocyte counts, compared to Groups A and B. During follow-up men with stable absolute lymphocyte counts did not relapse, a decreasing absolute lymphocyte count was associated with relapse within 18 months and the appearance of circulating prostate cells in the blood. After five years the absolute lymphocyte count decreased in Group B patients. A low absolute lymphocyte count one-month post-surgery or a decrease during follow-up was associated with an increased risk of treatment failure.
Conclusions: the absolute lymphocyte count is an important prognostic factor, it may change with time, a decrease is associated with pending biochemical failure and later appearance of circulating prostate cells.