This retrospective cohort study showed the prognostic utility of the CONUT score in patients with PTCL. The main findings of the study were as follows: first, the CONUT score was an independent prognostic factor for OS in PTCL; second, the Cox proportional hazards model with RCS showed an S-shaped relationship between the CONUT score and OS; and third, no significant interaction was found between the IPI and the CONUT score.
First, the present data showed that the CONUT score was associated with predicting OS across the entire spectrum of PTCL. The CONUT score is an efficient nutritional screening tool for assessing the nutritional status of patients and is useful for early detection of undernutrition 9. Malnutrition is prevalent in cancer patients, and nutritional status has a prognostic impact on disease progression and survival outcome 8. The frequent malnutrition in cancer patients may be due to decreased activity, inadequate intake of food, and abnormal catabolic metabolism. Poor nutritional status is correlated with the toxicity of chemotherapy, resulting in treatment reduction or interruption 17. The present findings were consistent with previous reports in other hematological malignancies, which showed the significant prognostic utility of the CONUT score in adult T-cell leukemia/lymphoma (ATLL) 11, DLBCL 12,13, multiple myeloma 14,15, myelodysplastic syndrome (MDS), and acute myeloid leukemia (AML) 16. This study is the first to confirm the prognostic impact of the CONUT score in patients with PTCL.
Second, the Cox proportional hazards model with RCS showed an S-shaped relationship between the CONUT score and OS. This relationship indicated that patients with a CONUT score ≥ 5 had a log hazard ratio of mortality risk over 0. Similarly, the optimal cut-off value of the CONUT score using the ROC curve for predicting the OS of PTCL was 5, the AUC was 0.629 (95% CI 0.519–0.740), sensitivity was 50.9%, and specificity was 77.3%. Nagata et al. reported the usefulness of the CONUT score in DLBCL; using an ROC curve with a cut-off value of 4, the AUC was 0.71 (95% CI 0.59–0.78), sensitivity was 59.3%, and specificity was 77.8% 12. Sakurai et al. also reported the utility of the CONUT score in MDS and AML; using an ROC curve with a cut-off value of 5, the AUC was 0.71 (95% CI 0.59–0.83), sensitivity was 84.4%, and specificity was 60.9%. The present finding was also supported by previous studies and involved only PTCL patients.
Third, no significant effect modification was found between the IPI and the CONUT score. The IPI was developed to predict outcomes in patients with aggressive non-Hodgkin lymphoma 18, and the usefulness of the IPI for PTCL was assessed in several studies 4,5. PTCL is not a homogeneous disease 19; thus, the modification by the IPI of the impact of the CONUT score on OS was evaluated. Although various prognostic factors for PTCL have been proposed, none has been reported to be superior to the IPI 7. Even patients with a low risk on the IPI have a poor prognosis. Recently, the prognostic importance of malnutrition assessment tools that directly reflect patient frailty independent of the IPI has been recognized 12. The CONUT score was an IPI-independent predictor for PTCL in the present study. Thus, the combination of the IPI with the CONUT score can serve to refine risk stratification further to dictate treatment strategy. Unfortunately, the present results could not provide the optimal treatment, and future study is required to improve the prognosis of patients with PTCL.
PTCL is heterogeneous, and the prediction of chemosensitivity is important to select optimal treatment. Various prognostic factors, such as the IPI and PIT, have been developed and validated for PTCL, but they have not led to stratified treatment 7. For patients with a high CONUT score may not be able to achieve long-term survival with conventional treatment, and it is necessary to establish new treatment methods or consider individualized treatment options in the future.
The present study was a multicentre, cohort study that was able to collect a relatively large number of patients with PTCL and to follow their long-term course. However, there were several limitations to this study. First, the current study was retrospective and could have had selection bias. Second, the study did not provide detailed information on treatment dose intensity or treatment toxicity. Third, the present study could not validate comparisons or combinations with other nutritional indicators or frailty scales. Finally, there is an absence of validation for the cut-off of the CONUT score, and these data warrant external validation in a future study.
In conclusion, the nutritional status evaluated by the CONUT score appears to be a prognostic factor in patients with PTCL, irrespective of IPI categories.