Тhe effect of metabolic variables on the duration of disease-free survival in patients with lymphomas who have 3 points on the PET scale after treatment: a retrospective study

INTRODUCTION : According to international and domestic clinical guidelines for assessing the response to treatment in patients with lymphomas according to PET/CT with FDG uses a 5-point PET scale based on changes in the level of uptake of RFLP in tumor masses. Of particular interest when using this scale are 3 points due to the difficulties in interpreting the data obtained in patients when assessing the prognosis of the disease. OBJECTIVE : Тo calculate and compare such metabolic quantities as the level of FDH absorption and tumor volume in patients with different periods of ED who had 3 points on the PET scale after treatment. Statistics: The MTV was determined using specialized software installed on the AW 4.7 (GE) workstation. The algorithm is an iterative mechanism for classifying the tumor/background within a selected area, applying a tissue weighting coefficient (w) to the SUV MAX values, set by default at 0.5 damage. Logistic regression was used to perform multifactorial analysis and build diagnostic models. The significance of regression coefficients was analyzed, and the odds ratio (OR) and the 95% confidence interval for it were estimated for significant regressors. A ROC analysis was performed to compare the quality of the forecast and select the best models. MATERIALS AND METHODS : The study included 97 patients with a score of 3 on the PET scale after treatment. In all patients, the tumor volume and the level of RF absorption were calculated in order to compare them. The Kruskal–Wallis test was used for comparative evaluation. The differences were considered statistically significant at the level of p < 0.05. RESULTS : As a result, the calculation and comparison of the averages of these values were carried out. In patients who underwent PFS for more than two years (n=69), the minimum average value of RF absorption was recorded when comparing the indicators before and during treatment, the difference was 6.5; the maximum average value of RF absorption was observed when comparing the indicators after and during treatment, the difference was 10.8, which is equivalent to 77.1% and 42.3% accordingly. The indicators of RF absorption and tumor volume differ statistically significantly depending on the following pairs of variables: %SUVperv/prom and %SUVperv/otv (p=0.016); %SUVperv/prom and %SUVprom/otv (p=0.045); %MTVperv/prom and % ΔMTVperv/rel (p=0.05). DISCUSSION : The main differences and at the same time advantages of our study from those presented above are a wider range of included types of lymphomas, in the study of S. Semary et al. (2024) this is only Hodgkin’s lymphoma, in the study of X. Li et al. (2020), David Z. Ng et al. (2022) this is only diffuse B-cell lymphoma, and in the study of H. Y. Yhim et al. (2018) this is peripheral T-cell lymphoma, at the same time, our study includes not only these types, but also follicular lymphoma and mantle zone lymphoma, which blurs the boundaries for expanding the scope of the results. In addition, these studies are based either on an assessment of the prognostic value of the scale itself, that is, on an assessment of only the result — 3 points, or on the use of the result — 3 points and the level of accumulation of RFLP, which distinguishes our study by using and evaluating not only the level of accumulation of RFLP, but also the tumor volume, which, according to X. Li et al. (2020), along with other quantitative values, will not only be more easily reproducible and comparable compared to the 5-point PET scale, but also more effective. In addition, in his opinion, they may turn out to be more accurate. I would also like to note that in our study we did not evaluate the three–year PFS or OS in patients with 3 and 4 points, but drew attention to a shorter period — two-year PFS and only in patients with 3 points on the PET scale, which, in our opinion, is also no less relevant. CONCLUSION : As a result, it was found that patients with a period of PFS of more than 24 months have statistically significant differences in both parameters, which can be used as an additional factor in predicting the disease.