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Departments of Preventive Medicine [K. T.] and Disaster and Emergency Medicine [M. H.], Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582; Division of Gastroenterology, National Kyushu Medical Center Hospital, Fukuoka 810-0065 [H. S.]; and Nakamura Gakuen University, Fukuoka 814-0198 [T. H.], Japan
| ABSTRACT |
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| INTRODUCTION |
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Numerous animal experiments have underscored a promoting role of testosterone in murine hepatocarcinogenesis (8, 9, 10, 11, 12, 13) , although the role of estrogens remains in dispute (13, 14, 15, 16, 17, 18) . In contrast, analytic epidemiological data on sex hormones and HCC have been sparse and controversial, except for the link between oral contraceptive use and HCC (19) . Yu and Chen (20) first described a positive association between serum testosterone level and risk of HCC in a nested case-control study in Taiwan, where hepatitis B virus represents a major causative agent. This positive association was replicated in a subsequent nested case-control study in Shanghai (21) , but the association was confounded by chronic hepatitis B virus infection, which was positively related to serum testosterone level. In a French follow-up study of male patients with LC mostly attributable to alcohol abuse (22) , neither testosterone nor estradiol level in serum was predictive of HCC occurrence. Because of the clear need for further studies on this issue, we performed a follow-up study of male cirrhotic patients mainly of hepatitis C virus origin, taking into account the effects of other clinicobiological measurements that are possibly associated with both serum hormone levels and HCC risk.
| MATERIALS AND METHODS |
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-fetoprotein level; (b) 4069 years of age;
(c) residents in Fukuoka or Saga prefecture (adjacent to
Fukuoka prefecture); and (d) of Japanese nationality. In
addition, patients with special forms of LC (primary or secondary
biliary cirrhosis and cirrhosis attributable to autoimmune hepatitis,
parasitosis, congestive heart failure, or metabolic disorders) were
excluded. Patients were regarded as having been enrolled when an
interview survey on their life styles, including a past history of
alcohol drinking, was successfully conducted by a trained interviewer.
Among the 100 patients, sera from 75 patients (48 men and 27 women)
were collected on the date of enrollment for outpatients or during
admission for inpatients. Of the 75 patients, 48 men were followed in
this study. In data analysis, we further eliminated 2 men whose
follow-up period was
6 months as described below, leaving 46 patients
(27 patients from the medicine department and 19 patients from the
surgery department; 35 outpatients and 11 inpatients; 44 residents in
Fukuoka prefecture and 2 residents in Saga prefecture). The median age
was 56 years. The diagnosis of LC was based on histology for 17
patients (37%), laparoscopy for 8 patients (17%), and evident
clinical signs (e.g., ascites and esophageal varices) and
laboratory/imaging findings for 21 patients (46%). The causes of LC
were considered to be hepatitis C virus infection
(n = 26), both hepatitis C virus infection
and alcohol (ethanol use
80 ml/day for
10 years;
n = 8), hepatitis B virus infection
(n = 4), both viral infections
(n = 1), alcohol (n = 4), and cryptogenic (n = 3). According
to the Child-Turcotte stage, 23 patients (50%) were classified as
stage A at enrollment, 18 patients (39%) as stage B, and 5 patients
(11%) as stage C. None of the 46 patients had received IFN therapy
during follow-up.
Follow-Up.
The end point in this study was defined as the development of HCC as a
final diagnosis >6 months after enrollment. The follow-up began on the
date of enrollment and finished upon the diagnosis of the end point,
death from other causes, loss to follow-up, or December 31, 1995,
whichever came first. For 33 patients who had been attending the
cooperating departments or relevant hospitals until the last date of
follow-up, serum
-fetoprotein level had been measured every month,
and ultrasound and/or computed tomography examination of the liver had
been performed every 36 months, followed by arteriography and/or
liver biopsy if HCC occurrence had been highly suspected. For the
remaining 15 patients, we investigated the vital status as of December
31, 1995 through municipal public offices retaining permanent address
records ("koseki" in Japanese). Nine patients were dead, and we
retrospectively determined whether they had developed HCC by contacting
attending physicians or their colleagues. For five of six survivors, we
could locate current attending physicians to obtain follow-up data. One
patient who had not been attending any hospital visited the cooperating
medicine department after telephone contact, and ultrasonography
revealed no evidence of HCC. Consequently, complete follow-up
information was obtained for all 48 patients. According to the
definition of the end point, 2 patients who had died or developed HCC
within the initial 6 months were excluded. Of the 46 patients used in
this study, 20 (43%) had developed HCC as the end point; 4 were
diagnosed from histology, 12 from angiography, and 4 from computed
tomography and/or ultrasonography; all of the last 4 patients had
subsequently died of the disease. The average (or median) follow-up
period was 5.1 (4.4) years, with the 5- and 10-year cumulative survival
rates of 61 and 17%, respectively.
Laboratory Tests.
Serum levels of albumin, aspartate aminotransferase, and
-fetoprotein at enrollment or, if unavailable, within 1 month before
or after enrollment, as well as the serostatus of hepatitis B surface
antigen determined by a reverse passive hemagglutination method
(Auscell; Abbott, Chicago, IL) were abstracted from medical records.
Serum specimens were frozen at -70°C until tested for hepatitis C virus markers and hormonal measurements. Antibodies to hepatitis C virus were determined by a second generation immunoradiometric assay (Ortho, Raritan, NJ). Positive results in this assay were further confirmed by a second generation recombinant immunoblot assay (Chiron, Emeryville, CA). In addition, all sera were tested for the presence of hepatitis C virus-RNA by reverse transcription polymerase reaction (Amplicor HCV; Roche Diagnostic Systems, Basel, Switzerland). Reactive results by the immunoblot assay, or indeterminate results by the assay with the presence of hepatitis C virus-RNA, were regarded as positive for antibodies to hepatitis C virus. Serum concentrations of testosterone, free testosterone, and estradiol were determined by specific 125I-radioimmunoassays (Coat-A-Count; DPC, Los Angeles, LA). SHBG was examined by a time-resolved fluoroimmunoassay (Delfia SHBG; Wallac Oy, Turku, Finland).
Statistical Analysis.
Serum T:E2 ratio was calculated as testosterone in ng/ml divided by
estradiol in ng/ml, although otherwise the estradiol level was
expressed in pg/ml. Each hormone-related variable was categorized at
tertiles. The cumulative incidence of HCC was calculated by the method
of Kaplan and Meier (24)
. The difference among the
incidence curves was evaluated by a log-rank test. Cox proportional
hazards models were used to estimate the HRs and their 95% CIs of
developing HCC for each hormonal variable with adjustment for potential
confounders including age (in years), years since LC diagnosis (<2
versus
2), department (internal medicine versus
surgery), hospitalization status (inpatient versus
outpatient), heavy drinking history (alcohol consumption
80 ml/day
for
10 years versus less), serum levels of albumin (g/dl),
aspartate aminotransferase [<72.5 units/l (median value among the
study subjects) versus
72.5 units/l], and
-fetoprotein
[<20 ng/ml (upper normal limit) versus
20 ng/ml], the
serostatus of hepatitis B surface antigen and antibodies to hepatitis C
virus, and other hormonal parameters (tertile classification; Ref.
25
). The Ps quoted were two-tailed, and those
<0.05 were considered statistically significant. Statistical analyses
were performed with the SAS (SAS Institute Inc., Cary, NC) and Stata
(StataCorp., College Station, TX) statistical packages.
| RESULTS |
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Table 1
shows the cumulative 5-year HCC incidence and the crude HRs according
to the tertile classification of each hormonal measurement. Raised
levels of testosterone and T:E2 ratio were associated with increased
risk (P = 0.03 and 0.06, respectively, by
log-rank tests), and the dose-response relation was clearest for T:E2
ratio (Table 1
and Fig. 1
); increased risk was observed both for patients with less than the
median length (4.4 years) of follow-up [HR (and 95% CI) in the upper
tertile relative to the middle and lower tertiles: 2.2 (0.76.8) for
testosterone and 2.0 (0.76.0) for T:E2 ratio] and for patients with
4.4 years of follow-up [corresponding HRs: 4.1 (0.820.5) for
testosterone and 3.5 (0.717.3) for T:E2 ratio]. Elevated risk was
also noted for SHBG, yet the association did not reach statistical
significance. Unlike testosterone, free testosterone was associated
with insignificantly decreased risk. The estradiol level was not
predictive of HCC risk in univariate analysis.
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A subgroup analysis of patients who tested seropositive for antibody to
hepatitis C virus but seronegative for hepatitis B surface antigen
(n = 34) gave similar HRs for serum
testosterone and T:E2 ratio as those in Tables 1
and 2
. For example,
the age- and albumin-adjusted HRs (and 95% CI) in the middle and upper
tertiles as compared with the lower tertile were 1.3 (0.26.6) and 4.2
(0.919.5) for testosterone (P for trend = 0.04) and 3.1 (0.812.6) and 5.5 (1.323.0) for T:E2 ratio
(P for trend = 0.02). For other etiological
categories, the sample size (5 patients seropositive for hepatitis B
surface antigen and 7 patients seronegative for both viral markers) was
too small to perform separate analyses.
| DISCUSSION |
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Analytic epidemiological data on androgens in causation of HCC remain scanty, although several HCC cases after anabolic androgenic steroid administration (31, 32, 33, 34) have been documented. In a nested case-control study in Taiwan where hepatitis B virus infection is a major cause of HCC, Yu and Chen (20) observed that the adjusted relative risk for HCC among men in the upper tertile of serum testosterone was 4.1 (95% CI, 1.313.2) compared with those in the middle and lower tertiles. A subsequent nested case-control study in Shanghai confirmed a similar positive association, but the association became no more evident after adjustment for serum hepatitis B surface antigen status (21) . Both studies evaluated serum testosterone alone, and no consideration was given to estrogens, free testosterone, or SHBG. Among our cirrhotic patients predominantly of hepatitis C virus origin (76%), increased risk was observed for elevated serum testosterone levels but more evidently for raised T:E2 ratio. It remains to be elucidated whether our finding holds true in other settings where hepatitis B virus or alcohol represents a predominant cause of LC. In a French follow-up study of 101 male cirrhotic patients (22) , serum SHBG, but neither testosterone nor estradiol, had a predictive value for HCC occurrence. The authors mentioned that the results in the first Chinese study (20) could not be extrapolated to older Western patients with cirrhosis mainly from alcoholic origin similar to those included in their study. In this study, SHBG appeared to be associated with increased risk in univariate analysis but not in fully adjusted analysis.
Voluminous experimental evidence suggests that androgens have promoting activity in hepatocarcinogenesis. Spontaneous hepatomas or preneoplastic liver lesions occur more frequently in male rodents than in females (8 , 35) . Male mice transgenic for hepatitis B virus (36) or hepatitis C virus (37) are more likely to spontaneously develop HCC than female counterparts. Male rodents are more susceptible to hepatocarcinogens (9 , 11 , 13 , 38, 39, 40) , and castration protects them against liver tumor induction (9 , 10 , 38, 39, 40) or the growth of enzyme-altered hepatic foci (12 , 13) whereas simultaneous administration of testosterone restores the susceptibility (9 , 10 , 12) . In castrated female rodents, testosterone administration also increases the growth of chemically induced preneoplastic liver lesions (11 , 13) . Antiandrogen treatment (e.g., chlormadinone acetate) exerts an inhibitory effect on chemical hepatocarcinogenesis in male rats (41) . Finally, androgen receptors are, more frequently and at a higher concentration, detected in human HCC than in the surrounding cirrhotic parenchyma (42 , 43) .
Conversely, the role of estrogens in the pathogenesis of HCC remains controversial. Initial clinical observations of benign and even malignant hepatocellular tumors in women taking oral contraceptives (44, 45, 46) prompted researchers to perform relevant animal experiments. Early data demonstrated promoting effects of estrogens, such as estradiol-17-phenylpropionate and estradiol benzoate (15) , mestranol (16) , and ethinyl estradiol (17) , on the development of hepatic foci, hepatic nodules, or HCC in rats, following the administration of hepatocarcinogens. However, several subsequent studies provided almost opposite findings. Mishkin et al. (14) observed an unexpected inhibitory effect of 17ß-estradiol and tamoxifen against liver tumor development induced chemically in rats. Yager et al. (18) showed that chronic treatment of ethinyl estradiol to rats caused an inhibition of regenerative liver growth, after an initial transient increase in liver growth. Shimizu et al. (13) also demonstrated a suppressive effect of estradiol valerate on glutathione S-transferase-positive foci in rats. The discrepancy across studies may result partly from the differences in sex steroid compounds used and the administration dose of each compound. Estrogen receptors have been detected in both human HCC and the surrounding liver tissue but usually at a lower concentration in the former (43 , 47, 48, 49) . In addition, estrogen receptors mutated in the hormone-binding domain have been implicated in a carcinogenic process among male cirrhotic patients through the escape from hormonal control (50) .
Although a significant independent association with serum estradiol was not evident in this study, the fully adjusted analysis revealed a risk reduction (HR, 0.4) in the upper tertile of the estradiol level, and the T:E2 ratio was found to be the best predictor of HCC among hormonal measurements. This suggests that elevated serum estradiol may confer a somewhat decreased risk of HCC, although the role of serum testosterone appeared predominant. The causal link between oral contraceptive use and HCC has been established in areas with a low prevalence of hepatitis virus infection (19) , yet such evidence cannot be extrapolated to the situation where the role of endogenous estrogens within almost physiological levels is examined among male patients with LC associated with hepatitis virus infection. It is conceivable that estrogens may exert both promoting and inhibitory effects on human hepatocarcinogenesis, depending on the dose, type, endogenous or exogenous origin, sex, and presence or absence of hepatitis virus infection.
To our knowledge, no other studies have examined serum T:E2 ratio as a predictor of HCC development in cirrhosis. Because this study was small and had less precision to estimate the associated HRs, larger studies are clearly required to consolidate our findings.
| ACKNOWLEDGMENTS |
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| FOOTNOTES |
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1 Supported in part by Grant 08670395 from the
Ministry of Education, Science, Sports and Culture, Japan. ![]()
2 To whom requests for reprints should be
addressed, at the Department of Preventive Medicine, Graduate School of
Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku,
Fukuoka 812-8582, Japan. Phone: 81-92-642-6112; Fax: 81-92-642-6115;
E-mail: ktanaka{at}phealth.med.kyushu-u.ac.jp ![]()
3 The abbreviations used are: HCC, hepatocellular
carcinoma; LC, liver cirrhosis; SHBG, sex hormone binding globulin;
T:E2 ratio, testosterone to estradiol ratio; HR, hazard ratio; CI,
confidence interval. ![]()
Received 1/ 3/00. Accepted 7/20/00.
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