Introduction: To determine if there was an association of the ALC (absolute lymphocyte count) and LCP (lymphocytopenia) with the expression of MMP-2 in bone marrow micro-metastasis, the changes occurring during follow-up and association with biochemical failure.
Methods and patients: One month after surgery blood and bone marrow samples were taken to determine the presence of micro-metastasis, the presence of circulating prostate cells (CPCs) and ALC. CPCs and micro-metastasis were detected using immunocytochemistry and MMP-2 expression determined in micro-metastasis. Only men positive for micro-metastasis participated in the study. At end follow blood was taken for serum PSA, ALC and CPCs, if the ALC decreased by more than 10% bone marrow sampling was repeated and MMP-2 expression determined, similarly for men with BF. Men who had stable ALCs had an end of study evaluation of the bone marrow.
Results: 402 men underwent radical prostatectomy, one month post surgery 79 men were positive for only bone marrow micro-metastasis and formed the study group; of whom 36/79 (45%) underwent BF. Clinical pathological findings were not significantly different between men with or without BF. In men with BF the ALC was significantly lower one-month post surgery. The 5 and 10 year Kaplan-Meier survival was 100% at 5-years and 65% at 10-years for the whole cohort. Men without BF had stable ALCs. A decrease of >10% in the ALC was associated with increasing MMP-2 expression in the micro-metastasis and surrounding stromal tissue, the appearance of CPCs 6-12 months later and BF.
Conclusions: the immune host-tumour cell interaction in the microenvironment is dynamic and changes with time. A decreasing ALC may be a valuable marker in identifying men with high risk of BF and changes in immune mediated dormancy before the PSA rises.
Keywords: Immune function; Prostate Cancer; biochemical failure; lymphocytopenia; minimal residual disease.