Rationale and objectives: Phosphoethanolamine and phosphocholine, shown to be elevated in tumors and possibly related to apoptotic signaling, have the potential to be prognostic variables of cancer treatment.
Materials and methods: The sum of phosphoethanolamine and phosphocholine normalized by nucleotide-triphosphates was determined in tumors of non-Hodgkin's lymphoma (NHL) patients via in vivo 31P MR spectroscopy.
Results: The normalized sum of phosphoethanolamine and phosphocholine showed significant differences in tumors of patients who had a complete response to treatment against those who did not (t-test: 1.45 +/- 0.15, mean +/- standard error, n = 10 vs. 2.28 +/- 0.15, n = 17, P < .001; Fisher test: P < .04; sensitivity and specificity approximately equal to 70%). This parameter also showed significant differences among treatment responses in the previously untreated and aggressive subgroups and in the low and low-intermediate-risk subgroups determined by the international prognostic index (IPI). Further, distinctly different treatment response cutoffs for the parameter were found in different risk groups. When these risk-dependent cutoffs were used, the Fisher test of the whole group improved (P < .0002, sensitivity 80%, specificity 94%). The normalized sum of phosphoethanolamine and phosphocholine and the IPI were better predictor covariates for time to treatment failure when fitted interactively in a Cox regression (P < .0003) than when fitted independently. When time to treatment failure was used as a surrogate of survival in Kaplan-Meier analysis, the interaction of both covariates segregated the cases significantly (P < .008). There was no significance with each covariate independently.
Conclusion: The normalized sum of phosphoethanolamine and phosphocholine measured before treatment successfully predicts long-term response to treatment and time to treatment failure in non-Hodgkin's lymphoma, particularly when combined with the IPI.