Acute lymphoblastic leukemia (ALL) is the most common pediatric malignancy, accounting for almost one-third of all childhood cancers worldwide, with an incidence of 20-35 per million children under 15 years (1). Mexico City has one of the highest childhood leukemia incidence rates in the world, with 49.5 cases per million children under 15 years of age (2). With the advent of multimodal therapy, the long-term survival rate of children with ALL has improved dramatically and exceeds 90% (3). However, these patients have a higher risk of presenting metabolic alterations during and after treatment, including obesity, dyslipidemia (hypertriglyceridemia, reduced levels of high-density lipoprotein cholesterol (HDL-C), and to a lesser extent, altered levels of total cholesterol and small-dense low-density lipoprotein (LDL-C), hypertension (4), increased adiposity and insulin resistance (5), which suggest an early risk of atherosclerosis and cardiovascular disease (6). These lipemic alterations are a common side effect of treatment with corticosteroids and L-asparaginase in pediatric patients with ALL (7). The side effects of L-asparaginase may be explained by the increase in the endogenous synthesis of very low-density lipoprotein (VLDL-C). In addition, corticosteroid therapy alters lipid and lipoprotein metabolism by increasing hepatic cholesterol synthesis (8). Mexico has the highest prevalence of overweight and obesity in the world (9) and an increased risk of developing metabolic syndrome (MS). Furthermore, several studies have reported that survivors of ALL are at increased risk of MS characterized by obesity (4, 10, 11). Additionally, our group of researchers reported that insulin resistance and body fat were predictive factors of developing MS in survivors of childhood cancer (12). On the other hand, recently, the atherogenic index of plasma (AIP) value has been used not only as an optimal indicator of dyslipidemia but also as a strong novel index for the risk of atherosclerosis and CVD (13).

Different authors have found associations between android fat (abdominal fat located around the trunk of the body) and gynoid fat (gluteal-femoral fat deposited around the hips and thighs) and/or the android/gynoid ratio (A/GR) and different risk factors for cardiovascular disease in children and adolescents (14). Although the etiology of these complications is not completely understood, it has been reported that drug administration, such as doxorubicin, glucocorticoids, and L-asparaginase, is associated with these alterations (5, 6, 15, 16).

Different studies have shown that patients with ALL presents a proinflammatory state at the time of diagnosis and during and after chemotherapy for up to 5 years after the start of treatment, characterized by increased levels of cytokines (IL-1β, IL-6, and TNF-α) (17). In this regard, Sadurska et al. indicated that survivors of childhood ALL are at high risk of developing early atherosclerosis, a multifactorial physiological process that develops over the long term in which dyslipidemia and inflammation are relevant (18).

On the other hand, several studies suggest that dietary supplementation with ω3-LCPUFAs, such as DHA and EPA, can be beneficial for cancer treatment, as it decreases metabolic risk; modulates several aspects of the inflammatory response; decreases inflammatory markers, plasma levels of TGs and LDL-C; and increases HDL-C (19). Nevertheless, studies using ω3-LCPUFAs supplementation in pediatric malignancies are limited (7, 20–22) Some studies have analyzed the effect of fatty acids on weight loss (23) and arm muscle circumference (24) or as adjuvant therapy (22). Previous studies investigating the ω3-LCPUFA effect on hyperlipidemia in children with ALL have reported dramatically reduced TG levels (7, 20, 21)

However, to our knowledge, there are no randomized controlled clinical trials comparing the direct changes in the lipid profile and inflammation markers induced by ω3-LCPUFA supplementation and assessing adherence to treatment by gas chromatography (gold standard) in ALL patients.

Therefore, we present results from a secondary analysis of data obtained in a randomized clinical trial that was previously conducted to evaluate the effect of supplementation with ω3-LCPUFAs on body composition in children with leukemia (under review).

The aim of the present analysis was to examine the effect of supplementation with ω3-LCPUFAs on several cardiometabolic factors in children undergoing treatment for ALL with the hypothesis that ω3-LCPUFAs reduce inflammatory cytokine and TGs levels and increase HDL-C in these patients.

We summarize the Consolidated Standards of Reporting Trials followed in this study in Figure 1 . The baseline characteristics of the children who participated in this study were similar across the treatment and control groups, Table 1 .

In this secondary analysis, we confirmed the effect of ω3-LCPUFA supplementation at a rate of 0.100 g/kg/day on the lipid profile, specifically on the TGs and VLDL-C concentrations during the first 3 months of ALL treatment. We observed a significantly lower concentration of TGs and VLDL-C in the ω3-LCPUFA group than in the placebo group. We found that 82.4% (28/34) of the children had hypertriglyceridemia and low levels of HDL at the time of ALL diagnoses. These results are consistent with previous findings from ALL studies (30–32). In addition, we reported a significantly decreased AIP ratio and IL-6 concentrations between the time of diagnosis and at 3 months in both groups. In contrast, the A/GR increased in both groups over time; the number of children classified in the > 95^th percentile was significantly lower in the ω3-LCPUFA group than in the placebo group during the administration of ω3-LCPUFAs. These results confirm that the intervention was effective because of the variation in the rate of change in erythrocyte membranes after supplementation with ω3-LCPUFAs.

There is considerable evidence that EPA and DHA have independent effects on multiple cardiometabolic risk factors, including blood pressure and cardiac function and lipids, as well as anti-platelet, anti-inflammatory, pro-resolving, and antioxidative actions (33). To our knowledge, as we mentioned before, there is a limited amount of information about the effects of ω3-LCPUFAs in a pediatric hematologic population. In addition, neither of these previous studies included the evaluation of the effect of ω3-LCPUFAs on cardiovascular risk factors, such as the VLDL-C levels, AIP, A/GR, and adiposity (body fat percentage), and not just the lipid profile. In this regard, only two studies have evaluated the effect of ω3-LCPUFAs on TGs and total cholesterol in children with ALL (7, 20). Laumann et al., in a pilot study in seven children with ALL (2-10 years), showed beneficial effects on TGs and total cholesterol levels of fish oil capsules containing 2.4 g - 4.8 g of EPA + DHA after the induction phase for six months. The authors reported a decrease in TGs concentrations at days 106 (p = 0.025) and 113 (p = 0.016) and in the total cholesterol concentration at day 113 (p = 0.027) in the intervention group compared to 22 historical controls. Nevertheless, when the authors corrected for one extra PEG-asparaginase dose, the level of significance in both lipid levels was reduced. In this study, the authors did not discuss the bias that the results could present in the intervention group because three patients presented a percentage of compliance of less than 80% (52%, 58%, and 78%). However, they recognized their limited sample size and the disadvantage of using historical controls, and the fact that it was not a randomized parallel-group trial. In our study, both groups were randomized, and the sample size, although small, was higher than that in Lauman’s study.

On the other hand, in a retrospective study, Salvador et al. (7) evaluated the effect of ω3-LCPUFAs (1000-3000 mg/day) in combination with acipimox (250 mg) in 9 patients with ALL with hypercholesterolemia and they observed a decrease in TGs and total cholesterol; however, one patient continued to present hypertriglyceridemia, so Bezalip 200 mg tablets (1 tablet/d) were added to his treatment. Under this therapy, TG levels dropped to the normal range. However, this study had the objective of demonstrating the effectiveness of the combination of omega-3 fatty acids with acipimox as a therapeutic alternative for hypertriglyceridemia and comparing its effectiveness in comparison with the side effects associated with the use of fibrates.

In contrast, we found differences in the total cholesterol between the groups at 3 months of supplementation; however, unexpectedly, the ω3-LCPUFA group presented a higher total cholesterol concentration (p = 0.009). These results contrast with those reported by Laumann and Salvador (7, 20). This difference is probably due in part to the maximum doses received of EPA + DHA in Laumann’s and Salvador’s studies (4.8 g and 2.5 g, respectively). Additionally, this result could be partly explained by using “Frebini Plus” milkshakes in both groups, which provided 15.7 g of lipids, and although we did not observe a difference in the groups at the basal time point, we show a tendency for the ω3-LCPUFA group to have a higher level of total cholesterol than that of the placebo group.

On the other hand, we did not find significant differences in HDL-C and LDL-C levels between the groups. In our study, we probably did not find differences since the shake provided in both groups contained 4.3 g of saturated fatty acids which might have influenced the result.

The AIP is a biomarker of atherogenic dyslipidemia that, through non-HDL-C and/or the TG/HDL-C ratio, can predict the risk of a future atherogenic cardiometabolic event from an early age (13, 34–36). Evidence in adults has shown that ω3-LCPUFA administration reduces the AIP. Golzari et al. (37) performed a randomized, double-blind, placebo-controlled clinical trial involving healthy controls and T2DM patients. The AIP was calculated as a proxy measure of atherosclerosis. The baseline AIP value was 0.97 vs. 0.64 after the trial (p =.009). In a longitudinal study (38) with 32 overweight and/or obese patients diagnosed with diabetes and hypertriglyceridemia who received fish oil (4.0 g/d) for eight weeks, Souza showed that fish oil supplementation effectively decreased the plasma atherogenic index. In this sense, we found that the omega group had a decrease in the AIP (0.75 vs. 0.27, p = 0.002) and in the percentage of patients with a high index (> 0.24) after finishing 3 months of follow-up.

Data on the potential effects of ω3-LCPUFAs on anti-inflammatory actions and cardiometabolic factors in children with ALL are scarce. Nevertheless, there is evidence that ω3-LCPUFAs, reduce inflammatory markers in adult oncology patients (39–41), as explained, n-3 PUFAs reduce promoting cytokines such as IL-1, TNF- α and IL-6 (42). Guo et al. (43), through a meta-analysis on ω3-LCPUFA supplementation and circulating levels of IL-6 and TNF-α in cancer patients, reported that ω3-LCPUFAs can reduce IL-6 and TNF-α levels. We observed significantly lower concentrations of IL-6 in the ω3-LCPUFA group than in the placebo group, additionally a reduction in TNF-α and IL-6 concentrations in both groups between diagnosis and at 3 months.

Based on these results, we should discuss the strengths and limitations of our work. A strength of the study was the use of a prospective cohort, which improved the accuracy of data collection. Another added benefit was the use of controls. In addition, supplementation at a rate of 0.100 g/kg/d (like Bayram et al.) (23) during early phase treatment of ω3-LCPUFAs was effective, and the adherence was measured through the fatty acid profile in erythrocytes (gold standard). On the other hand, body fat mass measurements were obtained using the DXA technique, which is an accurate and reliable measurement in children. A limitation of the study was the small sample size. Although this study has a significantly larger sample than the previous studies by Salvador et al. and Lauman et al. (7, 20),. In addition, in this study, we did not analyze what kinds of food they were eating. An additional limitation was lack of other predictors of atherogenesis such as the measurement of the intimal layer, apo B, etc., as the study was not initially intended for this purpose.

Although ω3-LCPUFAs have a positive effect on cancer patients, in ALL pediatric patients there is no sufficient data for recommendations. As we stated above, available studies from randomized placebo-controlled trials the supplements evaluated have varied in dose, source, time of intervention and kind of supplements used in these of ω3-LCPUFAs (7, 20, 23, 24, 44).

Dyslipidemia and inflammation have some common pathological links, such as obesity and cancer. Recent literature mentions that lipids have a fundamental role in the activation of inflammatory pathways, thus increasing the production of inflammatory cytokines (TNF-α, IL-6 and IL-1), which can promote the interruption of lipid metabolism, especially the reverse transport of cholesterol; this is related to a decrease in HDL-C, which could stimulate compensatory changes, such as the synthesis and accumulation of VLDL-C and hypertriglyceridemia, and ultimately increase cardiometabolic risk (45). On the other hand, the presence of metabolic syndrome in this population increases cardiovascular risk and vascular brain disease as a consequence of premature changes in the arterial wall, including endothelial cell damage (12, 46, 47).

These findings support the use of omega-3 fatty acids to reduce some adverse cardiometabolic and inflammatory risk factors in children with ALL. Our findings show that an ω3-LCPUFA intervention is feasible, and the results suggest that ω3-LCPUFA supplementation in these patients could help prevent, delay, and/or mitigate the development of dyslipidemia and cardiometabolic conditions that can have a negative impact on them. It is unknown if the effect of omega-3 may last longer than 3 months. We consider that large-scale trials are needed in children with cancer to confirm these results.

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

This study was approved by the Research and Ethics Committee of the Pediatric Hospital at the Mexican Social Security Institute (2009-785-107). We obtained written informed consent from parents and informed assent from children. Written informed consent to participate in this study was provided by the participants’ legal guardian/next of kin.

LB-C, designed the study, analyzed data, obtained funding, and prepared the manuscript; SA-M, EJ-A, JM-T and FM-B, contributed to the analysis and interpretation of data and helped prepare the manuscript; ML-A, JM-A performed the analysis and interpretation of data, and helped prepare the manuscript; SD-P, BG, JD-P, AA-B, human resource management, contributed to the analysis and interpretation of data, S-LK, BB-M, AJ-M, ZH-P, EJ-H, LE-H, NN-V, RP-C contributed to the acquisition of data. All authors contributed to the article and approved the submitted version.