Contraceptive steroids as a risk factor for hepatocellular carcinoma: a case/control study in South African black women

Oral Contraceptives Use and Liver Cancer Risk: A Dose-Response Meta-Analysis of Observational Studies

Studies about the association between oral contraceptives use and liver cancer risk have generated controversial results. Therefore, a meta-analysis of cohort and case-control studies was performed to quantitatively summarize the existing evidence.Eligible studies were identified by a computer search of PubMed and Embase databases and handed-search of reference lists, without any limitations. Study-specific risk estimates (RRs) with 95% confidence intervals (CIs) were combined with random-effects model.A total of 17 articles were included in this meta-analysis. Overall, there was no statistically significant association between oral contraceptives use and liver cancer risk (RR: 1.23, 95% CI: 0.93-1.63). In a dose-analysis of meta-analysis, a linear relationship between oral contraceptives use and liver cancer risk (P for linearity = 0.391) was found, although this correlation was not statistically significant.Oral contraceptives use was not positively associated with the risk of liver cancer.

Risk factors of hepatocellular carcinoma--current status and perspectives

Hepatocellular carcinoma is a common disorder worldwide which ranks 5th and 7th most common cancer among men and women. In recent years, different incidence trends have been observed in various regions, but the reasons are not completely understood. However, due to the great public efforts in HCC prevention and alternation of lifestyle, the roles of some well documented risk factors played in hepatocarcinogenesis might have changed. This paper summarizes both the environmental and host related risk factors of hepatocellular carcinoma including well established risk factors such as hepatitis virus infection, aflatoxin and alcohol, as well as possible risk factors such as coffee drinking and other dietary agents.

Parity, age at first birth, and risk of death from liver cancer: Evidence from a cohort in Taiwan

BACKGROUND AND AIM

The present study was undertaken to examine whether there is an association between parity and age at first birth and risk of liver cancer.

METHODS

The study cohort consisted of 1,292,462 women who had a first and singleton childbirth between 1 January 1978 and 31 December 1987. We tracked each woman from the time of their first childbirth to 31 December 2007, and their vital status was ascertained by linking records with the computerized mortality database. Cox proportional hazard regression models were used to estimate the relative risks (RR) of death from liver cancer associated with parity and age at first birth.

RESULTS

There were 826 liver cancer deaths during 32,464,186.58 person-years of follow-up. The mortality rate of liver cancer was 2.54 cases per 100,000 person-years. The adjusted RR was 1.59 (95% confidence interval [CI] = 1.36-1.86) for women who gave birth between 26 and 30, 2.41 (95% CI = 1.81-3.20) for women who gave birth between 31 and 35, and 6.26 (95% CI = 4.27-9.19) for women who gave birth after 35 years of age, respectively, when compared with women who gave birth at less than 25 years of age. The adjusted RR was 0.72 (95% CI = 0.59-0.87) for women who had two to three children, and 0.63 (95% CI = 0.47-0.84) for women with four or more births, respectively, when compared with women who had given birth to only one child.

CONCLUSIONS

The present study suggests that reproductive factors (parity and early age at first birth) may confer a protective effect on the risk of liver cancer.

Meta-analysis of epidemiologic studies on cigarette smoking and liver cancer

BACKGROUND

Whereas the International Agency for Research on Cancer (IARC) Monograph concluded that the evidence for the relationship between cigarette smoking and liver cancer is sufficient, the US Surgeon General's report summarized the data as suggestive but not sufficient.

METHODS

A meta-analysis of previous epidemiologic studies may help to clarify the potential association. We identified 38 cohort studies and 58 case-control studies in a systematic literature search for studies on liver cancer and cigarette smoking. The meta-relative risk (mRR) of liver cancer and dose-response trends were calculated. Tests for heterogeneity, publication bias assessment and influence analyses were performed.

RESULTS

Compared with never smokers, the adjusted mRR was 1.51 [95% confidence interval (CI) 1.37-1.67] for current smokers and 1.12 (95% CI 0.78-1.60) for former smokers. The increased liver cancer risk among current smokers appeared to be consistent in strata of different regions, study designs, study sample sizes and publication periods.

CONCLUSION

The results of our meta-analysis show that tobacco smoking is associated with liver cancer development, which supports the conclusion by the IARC Monograph. This conclusion has an important public health message for areas with high smoking prevalence and high liver cancer incidence such as China.

Oral contraception and the risk of hepatocellular carcinoma

BACKGROUNDS/AIMS

We performed a meta-analysis of observational epidemiological studies to examine the association between oral contraceptives (OC) and hepatocellular carcinoma (HCC).

METHODS

Two independent researchers conducted PubMed searches followed by systematic abstraction of studies that compared OC use between patients with HCC and a group of controls. Pooling of ORs was conducted using a random effects model. Heterogeneity and publication bias among studies were examined.

RESULTS

Twelve case-control studies that included 739 cases and 5223 controls met the inclusion and exclusion criteria. The pooled estimate of ORs (age- and sex-matched only) from all 12 studies was 1.57 (95% CI=0.96-2.54, p=0.07) with a heterogeneity of I(2)=39.9. Exclusion of one large multi-national European study decreased the heterogeneity to I(2)=16.9 and increased the pooled OR to 1.70 (95% CI=1.12-2.59, p=0.01). Eight studies reported adjusted ORs (in addition to age and sex); the pooled estimate was 1.45 (95% CI=0.93-2.27, p=0.11) with a heterogeneity of I(2)=20.4. Only few studies identified or adjusted for other HCC risk factors. Six studies showed a significant 2- to 20-fold increase in HCC risk with longer durations of OC use; however, the reporting was too inconsistent to allow meta-analysis.

CONCLUSIONS

The evidence is inconclusive to establish a relation between oral contraceptives and the risk of hepatocellular carcinoma. Future studies should focus on the duration, intermittency, and recency of OC use.

Occupational exposures and risks of liver cancer among Shanghai female textile workers--a case-cohort study

BACKGROUND

Liver cancer is the fifth most frequent malignancy worldwide. Viral hepatitis B and C, alcohol, and aflatoxin are the major established risk factors. Little is known about the aetiological contributions of occupational exposures, as previous occupational epidemiological studies of liver cancer suggest few agent-specific associations. We investigated associations of occupational exposures to dusts and chemicals in a cohort of female textile workers.

METHODS

Cancer incidence was determined among 267,400 female textile workers in Shanghai, China, who had been enrolled in an intervention trial of breast self-exam efficacy during 1989-98. Subjects were interviewed at baseline regarding basic demographics, smoking habits, alcohol consumption, and contraceptive practices. A case-cohort study of 360 liver cancer cases and 3,186 age-stratified randomly chosen subcohort subjects was conducted within this cohort. Exposures to workplace dusts and chemicals were reconstructed from complete work history data, historical exposure monitoring data for selected agents, and a specially designed job-exposure matrix for the textile industry. Relative risks and dose-response trends were estimated by Cox proportional hazards modelling, adapted for the case-cohort design. Latency analyses with different lag years were also applied.

RESULTS

2,095,904 person-years were contributed by this female cohort. The results of the case-cohort analysis revealed a protective effect of cotton fibre exposure years [adjusted hazards ratio (HR) = 0.64; 95% confidence interval (95% CI) 0.44-0.92] or endotoxin exposure (adjusted HR = 0.60; 95% CI 0.41-0.88) for the fourth quartile with significant trends for 20 year exposure lags.

CONCLUSIONS

This study suggests that chronic exposure to endotoxin or some other component of cotton dust exposure may have reduced liver cancer risk in this population.

Epidemiology of hepatocellular carcinoma

Year 2000 estimates of the incidence of cancer indicate that primary liver cancer remains the fifth most common malignancy in men and the eighth in women. The number of new cases has been predicted as 564,000, corresponding to 398,000 in men and 166,000 in women. The geographic areas at highest risk are located in Eastern Asia, Middle Africa, and some countries of Western Africa. Changes in incidence among migrant populations underline the predominant role of environmental factors in the etiology of primary liver cancer. In high-risk countries, the early cases of primary liver cancer occur already at ages 20 and above, underlying the impact of viral exposures early in life. In countries at low risk, primary liver cancer is rare before the 50s, translating the impact of late exposures with moderate risks and long latency intervals. Sex ratios are typically between 2 and 4. The incidence of primary liver cancer is increasing in several developed countries including the United States, and the increase will likely continue for several decades. The trend has a dominant cohort effect related to exposures to hepatitis B and C viruses. The variability of primary liver cancer incidence is largely explained by the distribution and the natural history of the hepatitis B and C viruses. The attributable risk estimates for the combined effects of these infections account for well over 80% of liver cancer cases worldwide. Primary liver cancer is the first human cancer largely amenable to prevention using hepatitis B virus vaccines and screening of blood and blood products for hepatitis B and C viruses.

Environmental factors and risk for hepatocellular carcinoma

Chronic infections with hepatitis B virus (HBV) and hepatitis C virus (HCV) are the most important risk factors for the development of hepatocellular carcinoma (HCC) in humans. HBV is the primary cause of HCC in high-risk areas including China and Africa, whereas in developed countries such as the United States, HCV plays a more prominent role and is at least partially responsible for the increase in HCC incidence in this country. Humans are exposed to hepatocarcinogenic aflatoxins through ingestion of moldy foods, a consequence of poor storage of susceptible grains. Highly exposed populations are primarily in sub-Sahara Africa and Asia, where dietary aflatoxins significantly enhance the carcinogenic effects of viral hepatitis. Heavy, long-term alcohol use is a risk factor for HCC, whereas moderate use (1-3 drinks/day) is not. Constituents of cigarette smoke are hepatic carcinogens in animals, and there is mounting evidence that the liver is an organ susceptible to tobacco carcinogenicity. Diabetic patients are at risk for HCC probably as a result of the hepatic injury, fibrosis, and eventual cirrhosis resulting from fatty liver disease. Given the current epidemic of obesity and diabetes in the United States, this risk factor will be increasingly important. Increased risk for HCC is evident in young noncirrhotic users of oral contraceptives in the United States and Europe. In summary, risk factors for HCC are identifiable in most patients and primarily are associated with chronic hepatic injury.

Primary liver cancer: worldwide incidence and trends

Estimates from the year 2000 indicate that liver cancer remains the fifth most common malignancy in men and the eighth in women worldwide. The number of new cases is estimated to be 564,000 per year, including 398,000 in men and 166,000 in women. In high-risk countries, liver cancer can arise before the age of 20 years, whereas, in countries at low risk, liver cancer is rare before the age of 50 years. Rates of liver cancer in men are typically 2 to 4 times higher than in women. The incidence of primary liver cancer is increasing in several developed countries, including the United States, and the increase will likely continue for some decades. The trend is a result of a cohort effect related to infection with hepatitis B and C viruses, the incidence of which peaked in the 1950s to 1980s. In selected areas of some developing countries, the incidence of primary liver cancer has decreased, possibly as a result of the introduction of hepatitis B virus vaccine. The geographic variability in incidence of primary liver cancer is largely explained by the distribution and the natural history of the hepatitis B and C viruses. The attributable risk estimates for the combined effects of these infections account for well over 80% of liver cancer cases worldwide. Primary liver cancer is the first human cancer largely amenable to prevention using hepatitis B virus vaccines and screening of blood and blood products for hepatitis B and C viruses.

Role of reproductive factors in hepatocellular carcinoma: Impact on hepatitis B- and C-related risk

Hepatocellular carcinoma (HCC) is more prevalent in men than in women. Estrogen may play some role in the development of HCC. We conducted a multicenter case-control study to evaluate the effects of reproductive factors on HCC risk, and to assess whether the association between each factor and HCC differs between hepatitis B surface antigen (HBsAg)-positive and -negative women, in which hepatitis C virus (HCV) is the major cause of HCC. The study included 218 women with HCC and 729 control women selected from nonbiological and first-degree female relatives of patients with HCC. The risk of HCC was inversely related to the number of full-term pregnancies (FTP) (P(trend) =.0216) and age at natural menopause (P(trend) =.0251 among women aged 45-55 without prior surgical menopause). Oophorectomy at age <or=50 during premenopausal years was also a risk factor (multivariate-adjusted OR, 2.57; 95% CI, 1.42-4.63). Use of hormone replacement therapy (HRT) (multivariate-adjusted OR, 0.46; 95% CI, 0.27-0.79) was associated with a lower risk of HCC, and there was a trend in the risk with increasing duration of HRT (P(trend) = 0.0013). All reproductive factors had a similar impact on HBsAg-positive and -negative women except for an early menarche (<or=12 vs. >or=16 years), which increased HCC risk in HBsAg carriers (multivariate-adjusted OR, 6.96; 95% CI, 2.52-19.18) but posed no increased risk in noncarriers (P(interaction) =.0053). In conclusion, increased exposure to estrogen during adulthood may provide a protective effect against HCC. Nevertheless, an early menarche, which results in early estrogen exposure, does not confer protection for HBsAg carriers.

Age at menarche and age at menopause in relation to hepatocellular carcinoma in women

OBJECTIVES

To assess whether age at menarche, age at menopause, parity, and selected blood hormones are associated with risk of hepatocellular carcinoma among women.

DESIGN

Case-control.

SAMPLE

and setting Data collected from 50 cases of hepatocellular carcinoma among women and 62 female controls with minor trauma or surgical conditions who attended one of three hospitals in Athens, Greece between 1995 and 1998.

METHODS

Researchers collected information on Reproductive variables and assayed sera samples for blood hormone levels and for chronic infection with Hepatitis B and C viruses. RESULTS Individuals with hepatocellular carcinoma had a lower mean age at menarche and a significantly higher mean age at menopause. After adjusting for potential confounding, age at menopause remained an important and significant predictor, increasing the risk of hepatocellular carcinoma 24% for each later year of menopause (P < 0.001). For each year that menarche was delayed, risk of hepatocellular carcinoma declined 21% (P = 0.100). Mean levels of insulin-like growth factor-1 and its binding protein were significantly reduced in cases compared with controls, while levels of oestradiol, testosterone and sex hormone binding globulin were somewhat higher among the cases.

CONCLUSIONS

This study provides indirect, but converging evidence that steroid hormones in general, and oestrogens in particular, play an important role in the aetiology of hepatocellular carcinoma among women.

Hepatocellular carcinoma

Hepatitis C infection is associated with the development of hepatocellular carcinoma, and progress has been made in a number of areas. Transgenic mice lines expressing the hepatitis C core protein develop hepatic steatosis, adenomas, and hepatocellular carcinomas, with no significant hepatitis or fibrosis. This implies that hepatitis C can lead directly to malignant transformation. A new lesion, irregular regeneration, has been described in chronic hepatitis C infection and is associated with a 15-fold increase in the relative risk of developing hepatocellular carcinoma. A minority of patients with hepatitis C-related hepatocellular carcinoma have intense lymphocytic infiltration of the cancer, a feature associated with a better prognosis. Several studies have confirmed the association between large cell dysplasia and hepatocellular carcinoma. However, large cell dysplasia may not be a premalignant lesion and instead may be a marker for premalignant alterations elsewhere in the liver. Oral contraceptives previously have been linked to an increased risk of hepatocellular carcinoma. A large multicenter European case-control study has shown minimal increased risk of hepatocellular carcinoma with use of steroidal contraception. Tamoxifen had shown promise in the management of advanced hepatocellular carcinoma. However, a randomized placebo-controlled study of 477 patients with hepatocellular carcinoma found no benefit from tamoxifen. In a preliminary study, however, octreotide has shown improved survival and quality of life in patients with advanced hepatocellular carcinoma. Finally, interferon treatment continues to be linked to a reduced risk of hepatocellular carcinoma in patients with hepatitis C. These studies generally are not randomized, and a randomized prospective study is required to address this issue.

Oral contraceptives and liver cancer. Results of the Multicentre International Liver Tumor Study (MILTS)

Many, but not all, previous epidemiological studies indicated a greater risk of hepatocellular cancer (HCC) in women who have used combined oral contraceptives for a long period of time, but no one has analyzed this risk based upon use of different formulations. It was decided to analyze specifically the risk of OC containing cyproterone acetate (CPA) after toxicological experiments in animals found hints for a potential genotoxicity. This report describes the risk associated with ever having used combined oral contraceptives (OC) among 317 cases of primary hepatocellular cancer (HCC) in women under age 65, compared with 1060 age-matched hospital and 719 population controls in a case-control study, which was conducted in six European countries. The adjusted odds ratio (unconditional logistic regression) for ever having used any OC was found to be 0.75 (0.54 to 1.03) when all cases were compared with all controls, and compared to hospital and population controls separately: 1.13 (0.86 to 1.48) and 0.78 (0.59 to 1.03), respectively. The adjusted odds ratios for OC containing all progestins of the CPA group were 0.89 (0.49 to 1.61); and 0.89 (0.37 to 2.18) for OC containing only CPA. There was no increase in risk for HCC with increasing duration of OC use among the different groups of OCs in the total group of cases with pooled controls. The risk estimates were not related to time since first or last use of any of the types of OCs considered. The most important risk factors for HCC were confirmed as a prior history of hepatitis B and C (adjusted odds ratio 3.1 (2.2; 4.3) and 37.9 (20.2; 70.9) for HBV and HCV, respectively). In the small subgroup of HCC cases without liver cirrhosis and with negative serology for HBV and HCV, there was evidence of an association with duration of OC use. No such trend was observed for the CPA group of OCs. Altogether, there is no evidence for an increased risk of HCC associated with CPA or CPA-like OCs. Oral contraceptives in the aggregate may enhance the risk of liver carcinomas not associated with HBV or HCV infection, but if so, this is an extremely rare adverse effect of their use.

Epidemiological characteristics and risk factors of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the major cancers in the world. There is a striking variation in HCC incidence rates between various countries, with a highest-to-lowest ratio of 112.5 for males and 54.7 for females. The high-risk populations are clustered in sub-Saharan Africa and eastern Asia. The male-to-female ratio for HCC ranges from < 1 to 6.4 and mostly from 2 to 4. There exist significant variations in the incidence of HCC among different ethnic groups living in the same area and among migrants of the same ethnic groups living in different areas. The age curves of HCC are significantly different in various countries, suggesting variability in exposure to risk factors. Chronic carriers of hepatitis B and C viruses (HBV and HCV, respectively) have an increased risk of HCC. The relative and attributable HCC risk of HBV and HCV carrier status varies in different countries. There exists a synergistic interaction on HCC between the two viruses. Aflatoxin exposure, cigarette smoking, heavy alcohol consumption, low vegetable intake, inorganic arsenic ingestion, radioactive thorium dioxide exposure, iron overload and the use of oral contraceptives and anabolic steroids have been documented as HCC risk factors. Recent molecular epidemiological studies have shown that low serum retinol levels as well as elevated serum levels of testosterone, neu oncoprotein and aflatoxin B1-albumin adduct are associated with an increased HCC risk. There is a synergistic interaction on HCC between chronic HBV infection and aflatoxin exposure. Familial aggregation of HCC exists and a major susceptibility gene of HCC has been hypothesized. Patients of some genetic diseases are at an increased risk of HCC. The genetic polymorphisms of cytochrome P450 2E1 and 2D6 and arylamine N-acetyltransferase 2 are associated with the development of HCC. A dose-response relationship between aflatoxin exposure and HCC has been observed among chronic HBV carriers who have null genotypes of glutathione S-transferase M1 or T1, but not among those who have non-null genotypes. Human hepatocarcinogenesis is a multistage process with the involvement of a multifactorial aetiology. Gene-environment interactions are involved in the development of HCC in humans.

Oral contraceptives and cancer. A review of the evidence

The following review considers epidemiological data published from 1990 onwards on oral contraceptives (OCs) and the risk of cancers of the breast, cervix uteri, endometrium, ovary, liver and skin. In several studies, breast cancer risk was seen to be elevated among women who were current users of an OC, or had recently stopped using an OC, whereas there was no residual risk 5 or more years after stopping OC use. No interaction was observed between type of OC, or with any recognised risk factor for breast cancer, or time-factor, except for some potential excess risk for women who started OC use at a young age. Most studies have confirmed that OCs moderately increase the risk of cervical cancer, particularly in human papilloma virus (HPV)-positive women, thus suggesting that OCs may act as a promoter for HPV-induced carcinogenesis. Recent epidemiological studies have confirmed that combined OCs provide substantial protection against endometrial and ovarian cancers, and results suggest that such protection is long-lasting, and may persist for 15 years or more after stopping OC use. Most case-control studies have shown a relationship between OC use and hepatocellular carcinoma. However, data from cohort studies or analysis of vital statistics indicate that the public health impact of such an association is modest, if not negligible. No association was observed between combined OC use and the incidence of skin melanoma, or any other common skin neoplasm. In terms of clinical and public health implications, the most relevant points regarding OC use are: (i) recent data confirm that OCs confer presistent protection against ovarian cancer; and (ii) any increased risk of breast cancer in OC users is moderate and is restricted to current/recent users. This is reassuring for younger women, whose baseline risk of this disease is extremely low.

Tamoxifen inhibits hepatoma cell growth through an estrogen receptor independent mechanism

BACKGROUND/AIMS

Tamoxifen has previously been shown to prolong the survival of patients with advanced stages of hepatocellular carcinoma and it has been suggested that it inhibits the growth of hepatoma cells through an estrogen receptor-dependent mechanism. We have studied the effects of the synthetic estrogen, mestranol, and the antiestrogen, tamoxifen, on the growth regulation of hepatoma cells in vitro.

METHODS

Cells were maintained under fully estrogenized conditions and were deprived of estrogen shortly before conducting experiments.

RESULTS

In the human hepatoma cell line Hep 3B, tamoxifen inhibited cell growth in a concentration and time-dependent manner with effective concentrations ranging from 0.1 microM to 10 microM. Mestranol inhibited cell growth at a concentration of 10 microM and had an additive effect with tamoxifen on growth inhibition. Expression of estrogen receptors in hepatoma cells was not detected by enzyme immunoassay, Northern blot analysis or reporter gene expression assay. Furthermore, the introduction of estrogen receptors into Hep 3B cells did not alter the effect of tamoxifen and mestranol on cell growth.

CONCLUSIONS

This study suggests that tamoxifen inhibits the growth of Hep 3B hepatoma cells through an estrogen receptor-independent mechanism.

Trends in mortality from primary liver cancer in England and Wales 1975-92: influence of oral contraceptives

Numerous case-control studies have suggested a link between the oral contraceptive pill and liver cancer. The secular trends in liver cancer mortality rates for England and Wales from 1975 to 1992 were examined to determine whether an effect of the pill was apparent. Liver cancer mortality has remained constant in women in the age groups that have had major exposure to the pill.

Better survival in female patients with hepatocellular carcinoma. Possible causes from a pathologic approach

BACKGROUND

Hepatocellular carcinoma is notably more prevalent in men than in women.

METHODS

To examine the sex-related characteristics of patients with primary hepatocellular carcinoma, 35 women were compared with 243 men, both groups having undergone surgical resection of the tumor.

RESULTS

Women had a lower incidence of tumor recurrence, with median disease free survival of 19.5 months compared with 4.5 months for men (P < 0.001). Women also had more favorable actuarial survival than men [36.5 months for women compared with 12.4 months for men (P = 0.002)]. Women had a significantly higher incidence (80%) of tumor encapsulation than men (45%) (P < 0.001). Furthermore, the tumors in women were frequently less invasive in terms of lower incidence of tumor microsatellites, liver invasion, and positive histologic margin. Tumor microsatellite formation was present with 16% of tumors in women, compared with 60% for men (P < 0.0001). Liver invasion was found in 37% of tumors in women and 61% in men (P = 0.03). Only 6% of tumors in women had a positive histologic margin, compared to 24% in men (P = 0.04). There was no statistical significance in the incidence of cirrhosis in the nontumorous liver, hepatitis B surface antigen positivity, mean age, or tumor size, between women and men.

CONCLUSIONS

Women who had hepatocellular carcinoma and hepatic resection had better survival rates and a lower rate of tumor recurrence than male patients. The better prognosis in women with hepatocellular carcinoma appeared to be related to the pathobiologic characteristics of the tumor (i.e., frequent encapsulation and lower tumor invasiveness).

Liveborn children and risk of hepatocellular carcinoma

Clinical, animal, and epidemiologic evidence indicates that exogenous steroids influence the risk of hepatocellular carcinoma (HCC) and a recent study suggested that parity also may increase the risk of this tumor in women. The latter hypothesis was evaluated in the data from a case-control study which was carried out in Athens and covered 166 male and 19 female cases of HCC, and 381 male and 51 female hospital controls. Among males, there was no association between the number of liveborn children and risk of HCC, whereas among women, there was a suggestive positive association. Compared with women with one or two children, the relative risk for HCC was 0.6 among nulliparous women, 1.3 among those with three or four children and 1.7 among those with five or more children. The association of parity with risk of HCC was limited to women who were positive for hepatitis-B surface antigen (HBsAg) and was not confounded by hepatitis-C virus infection or tobacco smoking. The small number of HCC cases does not permit firm conclusions. If confirmed, however, these results would provide the foundation for a practical preventive advice that could be given to women who are positive for HBsAg.

Oral contraceptives and primary liver cancer among young women

The association of oral contraceptive use with liver cancer was examined in a study of 76 deaths from primary liver cancer, 22 deaths from cancer of the intrahepatic bile ducts, and 629 controls among women aged 25 to 49 years. The subjects in the study are from the 1986 National Mortality Followback Survey, which included a questionnaire sent or administered to the next-of-kin of almost 20,000 deceased individuals in the United States. Information on a number of lifestyle factors was collected, including questions on oral contraceptive use. Increased risks of primary liver cancer were found for ever-users (odds ratio [OR] = 1.6, 95 percent confidence interval [CI] = 0.9-2.6), and for long-term (greater than or equal to 10 years) users (OR = 2.0, CI = 0.8-4.8) of oral contraceptives. When the analysis was restricted to subjects whose spouse or parent was the respondent, more pronounced risks were seen for ever-users (OR = 2.7, CI = 1.4-5.3) and long-term users (OR = 4.8, CI = 1.7-14.0). No clear excess risk was found for cancer of the intrahepatic bile ducts. This study, the largest to date, adds to the number of investigations demonstrating an increased risk of primary liver cancer with use, particularly long-term use, of oral contraceptives.

Depot-medroxyprogesterone acetate (DMPA) and risk of liver cancer. The WHO Collaborative Study of Neoplasia and Steroid Contraceptives

A hospital-based case-control study was conducted to assess the possible relationship between use of depot-medroxyprogesterone acetate (DMPA), an injectable progestational contraceptive, and the development of liver cancer in 2 developing countries where hepatitis B is endemic. Information about prior DMPA use and potential confounders was ascertained during personal interviews with 71 cases and 530 controls from 3 hospitals in Thailand and 1 hospital in Kenya. No significant association between liver cancer and DMPA use was observed in Kenya (RR = 1.64, 95% Cl = 0.4-0.6) or Thailand (RR = 0.33, 95% Cl = 0.1-1.0). No consistent changes in risk were observed with duration of use, time since last use, or time since first use. No significant associations were observed between DMPA use and risks of either hepatocellular carcinoma or cholangiocarcinoma. These findings suggest that risk of liver cancer in areas where hepatitis B is endemic is not appreciably altered by the use of DMPA.

The risk of liver neoplasia in relation to combined oral contraceptive use

Benign liver tumors occurring in young women were rarely reported in the medical literature before the introduction of oral contraceptives in the early 1960s. Subsequently, there were numerous case reports from the U.S. and other countries of liver tumors in women who used combined oral contraceptives. These reports, coupled with data from two U.S. case-control studies, indicate that the risk of hepatocellular adenoma increases sharply with increasing duration of oral contraceptive use. Case reports suggest that there may be a similar effect on the risk of focal nodular hyperplasia, but this is not established because there have been no case-control studies of the lesion. The incidence of benign liver disease attributable to oral contraceptive use in the U.S. is small because of the very low incidence of the disease. There have also been numerous case reports of malignant liver tumors in young women who used oral contraceptives. Seven case-control studies have been conducted--two in Great Britain, two in the U.S., one in Italy, one in several developing countries (conducted by the World Health Organization (WHO)), and one in South Africa. Data from the first five studies, all conducted in low risk populations, indicated an association of hepatocellular carcinoma (largely in the absence of liver cirrhosis) with oral contraceptive use. Because of small numbers estimates were unstable, but the risk did not appear to be increased appreciably for durations of use less than about five years. For longer durations, the risk appeared increased by five- to tenfold or more. There was little evidence of hepatitis B infection in the cases, but systematic determinations were not carried out. An increased risk of cholangiocarcinoma was not established, but few of these lesions were studied. Because the incidence of primary liver cancer in Northern Europe and the U.S. is low, the incidence attributable to oral contraceptive use is also likely to be low. The WHO study was carried out in eight countries, most of which have a high incidence of liver cancer and a high prevalence of a predisposing factor, hepatitis B infection. Similarly, the South African study was carried out among black women, and virtually all of the cases had serological evidence of hepatitis B infection. Both studies indicated no association of short-term oral contraceptive use with risk of hepatocellular carcinoma, and the WHO study indicated a lack of association with cholangiocarcinoma.

The WHO Collaborative Study of Neoplasia and Steroid Contraceptives: the influence of combined oral contraceptives on risk of neoplasms in developing and developed countries

A hospital-based case-control study was conducted in eight developing and three developed countries to determine whether use of combined oral contraceptives alters risks of various cancers. An observed trend of increasing risk of invasive cervical cancer with duration of use may not represent a causal relationship and is the subject of further study. Decreased risks of ovarian and endometrial carcinomas in users likely indicate a protective effect of oral contraceptives, the degree of which was similar in developing and developed countries. A small increase in risk of breast cancer in recent and current users was found to be somewhat greater in developing than developed countries. Both causal and non-causal interpretations of this finding have been offered. No associations were found between oral contraceptives and in situ cervical, hepatocellular, cholangio, or gallbladder carcinomas, or uterine sarcomas; but the power of this study to detect alterations in risks of these neoplasms in long-term users was low.