Refining histopathological growth pattern-based risk group discrimination in nodular lymphocyte-predominant Hodgkin lymphoma: an analysis from the German Hodgkin Study Group.

Histopathological growth patterns (GP) in nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) have previously been divided into GP AB (typical) vs CDEF (variant). However, it is unclear whether this division is optimal. We thus investigated alternative GP grouping approaches (GP ABC vs DEF; GP ABCF vs DE). Overall, 583 NLPHL patients who had first-line treatment within GHSG trials were included in the analysis. Median age was 39 years; 74% of patients were male; 76% presented with early-stage and 24% with advanced-stage disease. The 5-year and 10-year progression-free survival (PFS) estimates for all patients were 85.9% and 76.6%; overall survival (OS) estimates were 95.8% and 94.5%. Significant PFS and OS differences were detected for the comparison GP ABCF vs DE with worse outcomes for the GP DE group (HR: 1.7; 95%-CI: 1.1-2.7; HR: 2.5; 95%-CI: 1.1-5.7). No PFS and OS differences were observed for the comparisons GP AB vs CDEF and GP ABC vs DEF. Median time to death was shorter and death more often due to NLPHL in the GP DE (13 months; 66.7%) than in the GP ABCF (31 months; 5.6%) group. Hence, the division of GP into GP ABCF vs DE allows an optimized GP-based risk group discrimination in NLPHL.