Long-Term Vitamin K Antagonists and Cancer Risk: A Systematic Review and Meta-Analysis

Vitamin K1 inhibits ferroptosis and counteracts a detrimental effect of phenprocoumon in experimental acute kidney injury

Ferroptosis, a type of iron-dependent programmed cell death distinct from apoptosis, necroptosis, and other types of cell death, is characterized by lipid peroxidation, reactive oxygen species production, and mitochondrial dysfunction. Accumulating evidence has highlighted vital roles for ferroptosis in multiple diseases, including acute kidney injury. Therefore, ferroptosis has become a major focus for translational research. However, despite its involvement in pathological conditions, there are no pharmacologic inhibitors of ferroptosis in clinical use. In the context of drug repurposing, a strategy for identifying new uses for approved drugs outside the original medical application, we discovered that vitamin K1 is an efficient inhibitor of ferroptosis. Our findings are strengthened by the fact that the vitamin K antagonist phenprocoumon significantly exacerbated ferroptotic cell death in vitro and also massively worsened the course of acute kidney injury in vivo, which is of utmost clinical importance. We therefore assign vitamin K1 a novel role in preventing ferroptotic cell death in acute tubular necrosis during acute kidney injury. Since the safety, tolerability, pharmacokinetics, and pharmacodynamics of vitamin K1 formulations are well documented, this drug is primed for clinical application, and provides a new strategy for pharmacological control of ferroptosis and diseases associated with this mode of cell death.

Vitamin K intake and breast cancer incidence and death: results from a prospective cohort study

BACKGROUND & AIMS

Vitamin K prevents growth and metastasis of certain cancers, but there is little evidence regarding the association between dietary vitamin K and breast cancer incidence and death. We sought to examine whether intakes of total vitamin K, phylloquinone (vitamin K1) and menaquinones (MKs) (vitamin K2) may influence risks of breast cancer incidence and death in the US population.

METHODS

Herein, 2286 breast cancer cases and 207 breast cancer deaths were identified during 702,748 person-years of follow-up. Cox regression and competing risk regression were used to estimate multivariable-adjusted hazards ratios (HRs) and 95% confidence intervals (95% CIs) by dietary vitamin K intake quintile (Q) for risk of breast cancer incidence and mortality.

RESULTS

After adjustment for confounders, the total MK intake was associated with an increased risk of breast cancer (HR Q5 vs Q1, 1.26; 95% CI, 1.05 to 1.52; P_trend, 0.01) and death from breast cancer (HR Q5 vs Q1, 1.71; 95% CI, 0.97 to 3.01; P_trend, 0.04). Non-linear positive dose-response associations with risks of breast cancer incidence and death were found for total MKs intake (P_{non-linearity}<0.05). No statistically significant associations were observed between the intake of total vitamin K and phylloquinone and breast cancer.

CONCLUSIONS

The present study suggests that total MK intake was associated with an altered risk of the occurrence and death of breast cancer in the general US population. If our findings are replicated in other epidemiological studies, reducing dietary intake of menaquinones may offer a novel strategy for breast cancer prevention.

Natural Disasters in the Americas, Dialysis Patients, and Implications for Emergency Planning: A Systematic Review

Introduction

Natural hazards are elements of the physical environment caused by forces extraneous to human intervention and may be harmful to human beings. Natural hazards, such as weather events, can lead to natural disasters, which are serious societal disruptions that can disrupt dialysis provision, a life-threatening event for dialysis-dependent people. The adverse outcomes associated with missed dialysis sessions are likely exacerbated in island settings, where health care resources and emergency procedures are limited. The effect of natural disasters on dialysis patients living in geographically vulnerable areas such as the Cayman Islands is largely understudied. To inform predisaster interventions, we systematically reviewed studies examining the effects of disasters on dialysis patients and discussed the implications for emergency preparedness in the Cayman Islands.

Methods

Two reviewers independently screened 434 titles and abstracts from PubMed, Scopus, CINAHL, and Cochrane Library. We included studies if they were original research articles published in English from 2009 to 2019 and conducted in the Americas.

Results

Our search yielded 15 relevant articles, which we included in the final analysis. Results showed that disasters have both direct and indirect effects on dialysis patients. Lack of electricity, clean water, and transportation, and closure of dialysis centers can disrupt dialysis care, lead to missed dialysis sessions, and increase the number of hospitalizations and use of the emergency department. Additionally, disasters can exacerbate depression and lead to posttraumatic stress disorder among dialysis patients.

Conclusion

To our knowledge, this systematic review is the first study that presents a synthesis of the scientific literature on the effects of disasters on dialysis populations. The indirect and direct effects of disasters on dialysis patients highlight the need for predisaster interventions at the patient and health care system levels. Particularly, educating patients about an emergency renal diet and offering early dialysis can help to mitigate the negative effects of disasters.