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Habu D, Shiomi S, Tamori A, et al. Role of Vitamin K2 in the Development of Hepatocellular Carcinoma in Women With Viral Cirrhosis of the Liver. JAMA. 2004;292(3):358–361. doi:10.1001/jama.292.3.358
Author Affiliations: Departments of Hepatology (Drs Habu, Tamori, Takeda, and Nishiguchi), Nuclear Medicine (Dr Shiomi), Public Health (Dr Tanaka), and Surgery (Dr Kubo), Graduate School of Medicine, Osaka City University, Osaka, Japan.
Context Previous findings indicate that vitamin K2 (menaquinone)
may play a role in controlling cell growth.
Objective To determine whether vitamin K2has preventive effects on
the development of hepatocellular carcinoma in women with viral cirrhosis
of the liver.
Design, Setting, and Participants Forty women diagnosed as having viral liver cirrhosis were admitted
to a university hospital between 1996 and 1998 and were randomly assigned
to the treatment or control group. The original goal of the trial was to assess
the long-term effects of vitamin K2 on bone loss in women with
viral liver cirrhosis. However, study participants also satisfied criteria
required for examination of the effects of such treatment on the development
of hepatocellular carcinoma.
Interventions The treatment group received 45 mg/d of vitamin K2 (n = 21).
Participants in the treatment and control groups received symptomatic therapy
to treat ascites, if necessary, and dietary advice.
Main Outcome Measure Cumulative proportion of patients with hepatocellular carcinoma.
Results Hepatocellular carcinoma was detected in 2 of the 21 women given vitamin
K2 and 9 of the 19 women in the control group. The cumulative proportion
of patients with hepatocellular carcinoma was smaller in the treatment group
(log-rank test, P = .02). On univariate analysis,
the risk ratio for the development of hepatocellular carcinoma in the treatment
group compared with the control group was 0.20 (95% confidence interval [CI],
0.04-0.91; P = .04). On multivariate analysis with
adjustment for age, alanine aminotransferase activity, serum albumin, total
bilirubin, platelet count, α-fetoprotein, and history of treatment with
interferon alfa, the risk ratio for the development of hepatocellular carcinoma
in patients given vitamin K2 was 0.13 (95% CI, 0.02-0.99; P = .05).
Conclusion There is a possible role for vitamin K2 in the prevention
of hepatocellular carcinoma in women with viral cirrhosis.
We previously reported a 2-year study showing that vitamin K2 (menaquinone)
helps to prevent bone loss in women with viral cirrhosis of the liver.1 Most of the women agreed to participate in a longer
study to clarify the long-term effects of vitamin K2on bone loss
associated with cirrhosis. The incidence of hepatocellular carcinoma was found
to differ between women who received vitamin K2 and those who did
The participants in this study were 50 women with viral liver cirrhosis
who were admitted to a university hospital between 1996 and 1998. When the
results of abdominal dynamic computed tomography and abdominal ultrasonography
suggested the presence of hepatocellular carcinoma, abdominal angiography
or needle biopsy was performed to confirm the diagnosis. The diagnosis of
cirrhosis was based on histological examination of liver specimens obtained
by laparoscopy or needle biopsy performed under ultrasonic guidance.
Hepatocellular carcinoma was cofirmed in 3 women in the treatment group
and 4 in the control group. These 7 women were excluded from further study.
The remaining 43 women were randomly assigned using sealed envelopes to a
treatment or control group. The treatment group received 45 mg/d of vitamin
K2 (Glakay, Eisai Co, Tokyo, Japan). At the end of the first study,
21 women in the treatment group and 19 in the control group consented to participate
in a longer trial. All but 1 woman in each group had hepatitis C virus infection;
the other 2 women had hepatitis B infection. Seven women, 4 in the control
group and 3 in the treated group, had previously received interferon alfa
for their hepatitis C virus infections, but hepatitis C virus was not eradicated.
No one was given interferon therapy after study entry.
Surveillance for hepatocellular carcinoma was performed according to
detailed procedures recommended for follow-up of patients with liver cirrhosis
in Japan.2 Abdominal ultrasonography or abdominal
dynamic computed tomography was performed and serum α-fetoprotein levels
measured tumors at 3-month intervals. Any abnormality was followed up by tumor
biopsy or abdominal angiography to confirm a diagnosis of hepatocellular carcinoma.
Diagnosed cases of hepatocellular carcinoma were classified according
to the primary tumor, regional lymph nodes, and distant metastasis (TNM) system
of the International Union Against Cancer.3 Histopathologic
diagnosis of hepatocellular carcinoma was performed according to the criteria
proposed by Edmondson and Steiner.4 Compliance
with vitamin K2 in the treatment group was good; no patient had
adverse reactions or dropped out of the study. This trial was conducted in
accordance with the Declaration of Helsinki and was approved by the ethics
committee at the Osaka City University Medical School. Written informed consent
was obtained from each participant.
Statistical analysis was performed using SAS statistical software (version
8.12, SAS Institute Inc, Cary, NC). The χ2 test was used to
assess homogeneity between the groups. Cumulative incidences were plotted
using the Kaplan-Meier method and the statistical significance of differences
was analyzed using the log-rank test. Cox regression analysis was used for
univariate and multivariate analyses. P<.05 was
The 2 groups were similar with respect to age, virus type, platelets,
alanine aminotransferase, α-fetoprotein, and other clinical findings
(Table 1). Risk factors for hepatocellular
carcinoma5,6 were also similar
between the groups. After the first study commenced, hepatocellular carcinoma
was detected in 2 of the 21 patients given vitamin K2 and in 9
of the 19 patients in the control group (Figure 1). The cumulative proportion of women with hepatocellular
carcinoma was smaller in the treatment group compared with the control group
(log-rank test, P = .02; Figure 2). The clinical characteristics of the women in whom hepatocellular
carcinoma was detected during surveillance are shown in Table 2. All newly diagnosed cases of hepatocellular carcinoma were
stage I or II according to the International Union Against Cancer classification
and were given aggressive anticancer therapy. On univariate analysis, the
risk ratio for the development of hepatocellular carcinoma in the treatment
group compared with the control group was 0.20 (95% confidence interval, 0.04-0.91; P = .04; Table 3).
On multivariate analysis with adjustment for age, alanine aminotransferase
activity, serum albumin, total bilirubin, platelet count, α-fetoprotein,
and history of treatment with interferon alfa, the risk ratio for the development
of hepatocellular carcinoma in women given vitamin K2 was 0.13
(95% confidence interval, 0.02-0.99; P = .05; Table 4).
Vitamin K is a cofactor for the enzyme γ-glutamyl-carboxylase,
which converts glutamate residues into γ-carboxy-glutamate. Vitamin
K–dependent proteins include prothrombin II and the coagulation factors
VII, IX, X, proteins C and S, osteocalcin, surfactant-associated proteins,
and bone matrix protein. The vitamin K family of molecules comprises the natural
forms vitamin K1 (phylloquinone) and vitamin K2 (menaquinones)
and the synthetic form of vitamin K3 (menadione). These naphthoquinone-containing
molecules inhibit tumor cell growth in culture, with vitamin K3 being
more potent than either vitamin K1 or K2. Vitamin K2 inhibits growth of human cancer cell lines and induction of differentiation
in various human myeloid leukemia cell lines.7,8 Clinically,
vitamin K2 has successfully treated myelodysplastic syndrome.9
A number of findings indicate that vitamin K may play a role in controlling
cell growth. Underlying mechanisms possibly involve (1) cycling of oxidation
and reduction (as known for vitamin K3), (2) proteins with growth-inhibitory
properties induced by vitamin K, such as prothrombin,10 (3)
previously unidentified pathways involving arylation,11 (4)
or growth arrest genes such as gas 6.12 Geranylgeraniol,
which is a side chain of vitamin K2, strongly induces apoptosis
of tumor cells, suggesting that geranylgeraniol might play an important role
in inhibiting cell growth.13 The mechanisms
responsible for the inhibition of cell growth mediated by vitamin K2remain unexplained. These or other hypothetical mechanisms may have
contributed to the reduced hepatocellular carcinoma incidence among patients
receiving vitamin K2. Indeed, the annual incidence of hepatocellular
carcinoma in the control group was 8.8%, which is similar to the incidence
of hepatocellular carcinoma (7.9%; 32/107) in cirrhotic patients in Japan5 compared with 1.6% in the treatment group.
As shown in Table 4, the
albumin level showed the highest odds ratio for the development of hepatocellular
carcinoma. The serum albumin level is considered an important prognostic factor
in liver cirrhosis.14-17 Low
serum albumin levels in patients with liver cirrhosis are associated with
disease progression, poor nutritional status, and compromised immunity, which
increases the risk of carcinogenesis. The importance of low serum albumin
levels as a risk factor for hepatocellular carcinoma should be confirmed in
The original goal of our trial was to assess the long-term effects of
vitamin K2on bone loss in women with viral liver cirrhosis. Our
trial had several important limitations when the data were used to assess
the value of vitamin K2 for the primary prevention of hepatocellular
carcinoma in patients with liver cirrhosis, resulting from the small study
group, the inclusion of only women, and the participation of only 1 center.
However, similar to previously reported randomized controlled studies of cirrhosis
in which the primary end point was the development of hepatocellular carcinoma,
patients with evidence of hepatocellular carcinoma on highly sensitive imaging
studies were excluded, and the 2 study groups were similar with respect to
risk factors for hepatocellular carcinoma, such as age, severity of cirrhosis,
history of interferon therapy, and type of hepatitis virus infection. The
procedures used for the surveillance and diagnosis of hepatocellular carcinoma
were also similar to those used in our study. The sensitivity of these procedures
for the detection of hepatocellular carcinoma was underscored by the fact
that all of the detected cases of hepatocellular carcinoma were stage I or
stage II. Our results must also be tempered by the fact that 3 cases of hepatocellular
carcinoma were diagnosed in the control group within a year of enrollment.
These patients may have harbored occult disease at the time of enrollment.
Nonetheless, despite its small size, our study indicates that vitamin K2 decreases the risk of hepatocellular carcinoma to about 20% compared
with the control group, suggesting that vitamin K2 may delay the
onset of hepatocarcinogenesis. Moreover, the safety, relatively low cost,
and ease of use of vitamin K2 led to good compliance with treatment.
The results of this preliminary trial are intriguing and suggest that a potential
role for vitamin K2 to prevent hepatocarcinogenesis in patients
with liver cirrhosis. These results must be confirmed by multicenter randomized
controlled studies with the prevention of hepatocellular carcinoma by vitamin
K2 as the primary end point.