Prognostic impact of DNA ploidy pattern, S-phase fraction (SPF), and proliferating cell nuclear antigen (PCNA) in patients with primary gastric lymphoma

Abstract

Background: DNA ploidy, S-phase fraction (SPF), and proliferating cell nuclear antigen (PCNA) are considered to be significant prognostic factors in non-Hodgkin lymphomas. However, reports on their prognostic importance in gastric lymphoma patients are relatively lacking.

Methods: In the present study, we retrospectively studied the above-mentioned parameters in 29 patients with primary gastric lymphoma; 11/29 had B-low grade mucosa associated lymphoid tissue lymphoma (B-MALT), while 18/29 had diffuse large B-cell lymphoma (DLBCL), according to WHO classification. Proliferative activity was studied by staining against PCNA; in addition, the prognostic significance of DNA ploidy and SPF, as determined by flow cytometry, were investigated and compared to the results of the PCNA stainings.

Results: Seven out of 29 patients were found to have aneuploid tumors; DNA index values were >1 for all aneuploid lymphomas. There was no difference in DNA aneuploidy in MALT vs. DLBCL. The mean percentage of SPF was 11.4. SPF was found significantly lower in MALT vs. DLBCL (P < 0.05). The mean percentage of PCNA positive tumor cells was 52.6. PCNA protein expression was significantly lower in MALT vs. DLBCL (P < 0.0001). There was a significant positive correlation between PCNA score and SPF (P < 0.01, by Spearman analysis). DNA ploidy had no impact on survival in the present study. Both SPF and PCNA expression were important prognostic factors in the univariate analysis; however, in the multivariate analysis, the only independent prognostic factor for survival was PCNA expression.

Conclusions: These findings indicate that SPF and PCNA are significant prognostic factors in patients with primary gastric lymphomas. However, in the present study, DNA ploidy had no impact on survival in patients with primary gastric lymphomas.