Galina Shamayeva

Decreased Cancer Risk After Iron Reduction in Patients With Peripheral Arterial Disease: Results From a Randomized Trial

BACKGROUND Excess iron has been implicated in cancer risk through increased iron-catalyzed free radical-mediated oxidative stress. METHODS A multicenter randomized, controlled, single-blinded clinical trial (VA Cooperative Study #410) tested the hypothesis that reducing iron stores by phlebotomy would influence vascular outcomes in patients with peripheral arterial disease. Patients without a visceral malignancy in the last 5 years (n = 1277) were randomly assigned to control (n = 641) or iron reduction (n = 636). Occurrence of new visceral malignancy and cause-specific mortality data were collected prospectively. Cancer and mortality outcomes in the two arms were compared using intent-to-treat analysis with a Cox proportional hazards regression model. Statistical tests were two-sided. RESULTS Patients were followed up for an average of 4.5 years. Ferritin levels were similar in both groups at baseline but were lower in iron reduction patients than control patients across all 6-month visits (mean = 79.7 ng/mL, 95% confidence interval [CI] = 73.8 to 85.5 ng/mL vs 122.5 ng/mL, 95% CI = 115.5 to 129.5 ng/mL; P < .001). Risk of new visceral malignancy was lower in the iron reduction group than in the control group (38 vs 60, hazard ratio [HR] = 0.65, 95% CI = 0.43 to 0.97; P = .036), and, among patients with new cancers, those in the iron reduction group had lower cancer-specific and all-cause mortality (HR = 0.39, 95% CI = 0.21 to 0.72; P = .003; and HR = 0.49, 95% CI = 0.29 to 0.83; P = .009, respectively) than those in the control group. Mean ferritin levels across all 6-monthly visits were similar in patients in the iron reduction and control groups who developed cancer but were lower among all patients who did not develop cancer than among those who did (76.4 ng/mL, 95% CI = 71.4 to 81.4 ng/mL, vs 127.1 ng/mL, 95% CI = 71.2 to 183.0 ng/mL; P = .017). CONCLUSIONS Iron reduction was associated with lower cancer risk and mortality. Further studies are needed to define the role of body iron in cancer risk.

Ferritin levels, inflammatory biomarkers, and mortality in peripheral arterial disease: A substudy of the Iron (Fe) and Atherosclerosis Study (FeAST) Trial

BACKGROUND This study delineated correlations between ferritin, inflammatory biomarkers, and mortality in a cohort of 100 cancer-free patients with peripheral arterial disease (PAD) participating in the Veterans Affairs (VA) Cooperative Study #410, the Iron (Fe) and Atherosclerosis Study (FeAST). FeAST, a prospective, randomized, single-blind clinical trial, tested the hypothesis that reduction of iron stores using phlebotomy would influence clinical outcomes in 1227 PAD patients randomized to iron reduction or control groups. The effects of statin administration were also examined in the Sierra Nevada Health Care (SNHC) cohort by measuring serum ferritin levels at entry and during the 6-year study period. No difference was documented between treatment groups in all-cause mortality and secondary outcomes of death plus nonfatal myocardial infarction and stroke. Iron reduction in the main study caused a significant age-related improvement in cardiovascular disease outcomes, new cancer diagnoses, and cancer-specific death. METHODS Tumor necrosis factor (TNF)-alpha, TNF-alpha receptors 1 and 2, interleukin (IL)-2, IL-6, IL-10, and high-sensitivity C reactive protein (hs-CRP) were measured at entry and at 6-month intervals for 6 years. Average levels of ferritin and lipids at entry and at the end of the study were compared. The clinical course and ferritin levels of 23 participants who died during the study were reviewed. RESULTS At entry, mean age of entry was 67 +/- 9 years for the SNHCS cohort, comparable to FeAST and clinical and laboratory parameters were equivalent in substudy participants randomized to iron reduction (n = 51) or control (n = 49). At baseline, 53 participants on statins had slightly lower mean entry-level ferritin values (114.06 ng/mL; 95% confidence interval [CI] 93.43-134.69) vs the 47 off statins (127.62 ng/mL; 95% CI, 103.21-152.02). Longitudinal analysis of follow-up data, after adjusting for the phlebotomy treatment effect, showed that statin use was associated with significantly lower ferritin levels (-29.78 ng/mL; Cohen effect size, -0.47 [t(df, 134) = 2.33, P = .02]). Mean follow-up average ferritin levels were higher in 23 participants who died (132.5 ng/mL; 95% CI, 79.36-185.66) vs 77 survivors (83.6 ng/mL; 95% CI, 70.34-96.90; Wilcoxon P = .05). Mean follow-up IL-6 levels were higher in dead participants (21.68 ng/mL; 95% CI, 13.71-29.66) vs survivors (12.61 ng/mL; 95% CI, 10.72-14.50; Wilcoxon P = .018). Ferritin levels correlated (Pearson) with average IL-6 levels (r = 0.1845; P = .002) and hsCRP levels (r = .1175; P = .04) during the study. CONCLUSION These data demonstrate statistical correlations between levels of ferritin, inflammatory biomarkers, and mortality in this subset of patients with PAD.

Effect of controlled reduction of body iron stores on clinical outcomes in peripheral arterial disease.

BACKGROUND Published results from a controlled clinical trial in patients with peripheral arterial disease found improved outcomes with iron (ferritin) reduction among middle-aged subjects but not the entire cohort. The mechanism of the age-specific effect was explored. METHODS Randomization to iron reduction (phlebotomy, n = 636) or control (n = 641) stratified by prognostic variables permitted analysis of effects of age and ferritin on primary (all-cause mortality) and secondary (death, nonfatal myocardial infarction, and stroke) outcomes. RESULTS Iron reduction improved outcomes in youngest age quartile patients (primary outcome hazard ratio [HR] 0.44, 95% CI 0.21-0.92, P = .028; secondary outcome HR 0.34, 95% CI 0.19-0.61, P < .001). Mean follow-up ferritin levels (MFFL) declined with increasing entry age in controls. Older age (P = .035) and higher ferritin (P < .001) at entry predicted poorer compliance with phlebotomy and rising MFFL in iron-reduction patients. Intervention produced greater ferritin reduction in younger patients. Improved outcomes with lower MFFL were found in iron-reduction patients (primary outcome HR 1.11, 95% CI 1.01-1.23, P = .028; secondary outcome HR 1.10, 95% CI 1.0-1.20, P = .044) and the entire cohort (primary outcome HR 1.11, 95% CI 1.01-1.23, P = .037). Improved outcomes occurred with MFFL below versus above the median of the entire cohort means (primary outcome HR 1.48, 95% CI 1.14-1.92, P = .003; secondary outcome HR 1.22, 95% CI 0.99-1.50, P = .067). CONCLUSIONS Lower iron burden predicted improved outcomes overall and was enhanced by phlebotomy. Controlling iron burden may improve survival and prevent or delay nonfatal myocardial infarction and stroke.

The Statin–Iron Nexus: Anti-Inflammatory Intervention for Arterial Disease Prevention

OBJECTIVES We postulated the existence of a statin-iron nexus by which statins improve cardiovascular disease outcomes at least partially by countering proinflammatory effects of excess iron stores. METHODS Using data from a clinical trial of iron (ferritin) reduction in advanced peripheral arterial disease, the Iron and Atherosclerosis Study, we compared effects of ferritin levels versus high-density lipoprotein to low-density lipoprotein ratios (both were randomization variables) on clinical outcomes in participants receiving and not receiving statins. RESULTS Statins increased high-density lipoprotein to low-density lipoprotein ratios and reduced ferritin levels by noninteracting mechanisms. Improved clinical outcomes were associated with lower ferritin levels but not with improved lipid status. CONCLUSIONS There are commonalities between the clinical benefits of statins and the maintenance of physiologic iron levels. Iron reduction may be a safe and low-cost alternative to statins.

Statins and biomarkers in claudicants with peripheral arterial disease: cross-sectional study.

This exploratory substudy of The Iron (Fe) and Atherosclerosis Study (FeAST) compared baseline inflammatory markers, including cytokines, C-reactive protein (CRP), and ferritin, in subjects with peripheral arterial disease (PAD) taking statins with subjects with PAD who were not taking statins. Inflammatory markers in the serum of 47 subjects with PAD not taking statins and a healthy cohort of 21 medication-free men were compared with 53 PAD subjects taking statins at entry to the FeAST. Healthy subjects demonstrated lower levels of tumor necrosis factor (TNF)-R1, interleukin-6 (IL-6), and CRP. TNF-α R1 averaged 2.28 ng/mL versus 3.52 ng/mL, p  =  .0025; IL-6 averaged 4.24 pg/mL versus16.61 pg/mL, p  =  .0008; and CRP averaged 0.58 mg/dL versus 0.92 mg/dL, p  =  .0192. A higher level of IL-6 was observed in PAD statin takers versus PAD subjects not taking statins: 19.47 pg/mL versus 13.24 pg/mL, p  =  .0455. As expected, total cholesterol and low-density lipoprotein levels were lower in the statin-treated group, p  =  .0006 and p  =  .0001, respectively. No significant differences in inflammatory cytokines were detected for varying doses of simvastatin. Additionally, no significant differences in inflammatory biomedical markers were found in subjects with PAD alone compared with those with concomitant coronary artery disease (CAD). Unexpectedly, serum inflammatory cytokine IL-6 levels were significantly higher in PAD subjects receiving statins. There was no difference in measured inflammatory markers in PAD subjects with concomitant CAD.

Reduction of iron stores and clinical outcomes in peripheral arterial disease: outcome comparisons in smokers and non-smokers.

A prospective randomized trial suggested that iron (ferritin) reduction improved outcomes in smokers. The present study reanalyzed the trial results in smokers compared with non-smokers. Randomization of 1262 men with peripheral arterial disease (540 smokers and 722 non-smokers) to iron reduction (phlebotomy) or control groups permitted analysis of the effects of iron reduction and smoking on primary (all-cause mortality) and secondary (death plus non-fatal myocardial infarction or stroke) endpoints. Iron reduction resulted in significant improvement in the primary (hazard ratio [HR] 0.661, 95% confidence interval [CI] 0.45, 0.97; P = 0.036) and secondary (HR 0.64, 95% CI 0.46, 0.88; P = 0.006) endpoints compared with controls in smokers but not in non-smokers. Smokers required removal of a greater volume of blood to attain targeted ferritin reduction as compared with non-smokers (P = 0.003) and also exhibited differing characteristics from non-smokers, including significantly less statin use. Phlebotomy-related outcomes favored smokers over non-smokers. Biological linkages responsible for this unique effect offer promising lines for future iron reduction studies (ClinicalTrial.Gov Identifier: NCT00032357).

Racial Health Disparities, and Variant Red Cell and Iron Homeostasis

Oxidative stress from excess iron may contribute to racial health disparities. Previously we reported improved clinical outcomes with lower ferritin and higher percent transferrin saturation (%TS) levels in White but not Black participants with peripheral arterial disease entered to a clinical trial. This report demonstrates racially variant interactions between hemoglobin, ferritin, and %TS levels. Lower hemoglobin and %TS levels, and higher ferritin levels were documented in Black compared with White participants within cardiovascular disease risk categories. Ferritin levels near 80 ng/mL related to higher hemoglobin levels in White but not Black participants. Higher %TS levels with ferritin levels above 80 ng/mL in White participants were blunted in Black participants. Ferritin/%TS ratios were significantly higher in Black than White participants. Iron incorporation into hemoglobin and scavenging by transferrin may buffer iron toxicity more effectively in White than in Black individuals. Metabolic vulnerability to iron excess may explain, in part, racial health disparities.

Racial Differences in Iron Measures and Outcomes Observed during an Iron Reduction Trial in Peripheral Arterial Disease

Elevated body iron (ferritin) levels may contribute to adverse health outcomes. Racial differences in iron measures and clinical outcomes were observed during an iron reduction trial in peripheral arterial disease. At entry, Black compared with White participants had higher ferritin and lower red cell measures, as well as differing ferritin and percent transferrin saturation (%TS) responses, and HDL/LDL ratios associated with statin use. Lower hematocrit levels during follow-up resulted in fewer phlebotomies, less iron unloading (ferritin reduction, p=.035) and 32% less iron removed in Black compared with White participants randomized to iron reduction. Improved primary (all-cause mortality) and secondary (death plus non-fatal myocardial infarction and stroke) outcomes among White participants correlated with lower ferritin levels (p=.005 and p=.053, respectively) and higher %TS levels (p<.001 and p=.001 respectively), associations not observed in Black participants. Variant iron homeostasis contributory to racial health disparities warrants personalized intervention strategies and race-specific clinical trial design.