Diffuse large B-cell lymphoma (DLBCL) is the most common non-Hodgkin lymphoma (NHL), making up to about 30%-40% of NHL in the U.S. PET-CT scan is recommended as the most accurate imaging technique in DLBCL for staging and response assessment. Pretreatment assessment of PET-CT scan derived metrics such as total metabolic tumor volume (TMTV) has been shown to correlate with progression-free survival (PFS) and overall survival (OS) in DLBCL. In our study, we evaluated the prognostic significance of pretreatment TMTV on event-free survival (EFS) at 24-months. We also evaluated the correlation between pretreatment TMTV, total lesion glycolysis (TLG) and cell of origin (COO). TMTV was calculated using a threshold of 41% of the max pixel value (based on prior studies) to draw the volume of interest (VOI) for a lesion. A pooled t-test was performed to compare TMTV, TLG and COO with EFS at 24 months. Chi-Square test compared TMTV with COO. The median age was 58 years, with a median duration of follow up of 26 months. The mean pretreatment TMTV and pretreatment TLG was 295 cm3 and 4519 units, respectively. Amongst all patients, 19.2% had an event within 24 months. When TMTV was compared to EFS at 24 months, the mean TMTV was 304 cm3 for those who had an event versus 294 cm3 without (p=0.95). TLG, compared to EFS at 24 months showed a mean TLG of 3391 for those who had an event versus 4914 without (P=0.40). COO, when compared with TLG, had means of 4365 and 4933 for germinal center (GCB) and non-germinal center (non-GCB) subtypes, respectively with a p=0.79. This study demonstrates a lack of prognostic significance of pretreatment PET scan on EFS at 24 months in DLBCL and lack of correlation between pretreatment TMTV, TLG, COO and EFS at 24. Higher TMTV correlated with inferior PFS and retains its prognostic significance as determined by prior studies. Larger sample size is required to determine the validity of our findings.
Diffuse Large B-cell Lymphoma, Positron-Emission Tomography scan, Tumor Burden, Total Metabolic Tumor Volume, Total Lesional Glycolysis, Prognosis, Event-free survival, Cell of Origin