High Serum Alpha-fetoprotein Level Research Articles

Establishment and characterization of primary canine hepatocellular carcinoma cell lines producing alpha-fetoprotein

A primary cultured cell line named CHKS was established from a hepatocellular carcinoma (HCC) of a dog showing a high level of serum alpha-fetoprotein (AFP). CHKS secreted a 66 KDD AFP into the growth medium regardless of the presence or absence of fetal bovine serum (FBS). Cloning CHKS with limiting dilution produced 4 clones, CHKS-1, -2, -3, and -4, which secreted 826, 471, 70, and less than 10 ng/ml, respectively, of AFP into the culture medium. In culture, these cell lines were similar in morphology and proliferation pattern to epithelial cells and positive to periodic acid–Schiff (PAS) staining. The presence of mRNA for canine albumin was demonstrated by nested PCR. The doubling times of the clone cell lines were 21, 45, 36, and 35 h, saturation densities 34, 18, 22, and 24 × 10 4/cm 2, and plating efficiencies 18, 45, 46, and 45%, respectively. Chromosome analysis of these cell lines showed near triploidy. These results show that CHKS and its clones have hepatic cell functions and are useful for carcinogenetic and clinical studies of canine HCC.

Ataxia with oculomotor apraxia type 2

Ataxia with oculomotor apraxia type 2 (AOA2) is characterized by onset between age 10 and 22 years, cerebellar atrophy, peripheral neuropathy, oculomotor apraxia (OMA), and elevated serum alpha-fetoprotein (AFP) levels. Recessive mutations in SETX have been described in AOA2 patients. To describe the clinical features of AOA2 and to identify the SETX mutations in 10 patients from four Italian families. The patients underwent clinical examination, routine laboratory tests, nerve conduction studies, sural nerve biopsy, and brain MRI. All were screened for SETX mutations. All the patients had cerebellar features, including limb and truncal ataxia, and slurred speech. OMA was observed in two patients, extrapyramidal symptoms in two, and mental impairment in three. High serum AFP levels, motor and sensory axonal neuropathy, and marked cerebellar atrophy on MRI were detected in all the patients who underwent these examinations. Sural nerve biopsy revealed a severe depletion of large myelinated fibers in one patient, and both large and small myelinated fibers in another. Postmortem findings are also reported in one of the patients. Four different homozygous SETX mutations were found (a large-scale deletion, a missense change, a single-base deletion, and a splice-site mutation). The clinical phenotype of oculomotor apraxia type 2 is fairly homogeneous, showing only subtle intrafamilial variability. OMA is an inconstant finding. The identification of new mutations expands the array of SETX variants, and the finding of a missense change outside the helicase domain suggests the existence of at least one more functional region in the N-terminus of senataxin.

A Rare Case of Recurrent Alpha-fetoprotein-producing Gastric Cancer without Re-elevation of Serum AFP

We report an extremely rare case of recurrent alpha-fetoprotein (AFP)-producing gastric cancer without re-elevation of serum AFP. The patient was a 78-year-old woman with AFP-producing gastric cancer, a rare type of gastric adenocarcinoma. A Borrmann III gastric tumour was surgically resected and AFP-producing gastric cancer was diagnosed based on high levels of serum AFP (705.44 ng/ml) and immunohistochemical examination of the tumour. The serum AFP level decreased to the normal range after resection without any sign of recurrence by imaging, but the patient developed local recurrence of the cancer and died 13 months after surgery. No re-elevation of serum AFP levels was observed after recurrence. Although serum AFP levels are believed to be useful for follow-up in the post-operative period, the possibility that serum AFP levels do not always correlate with the extent of the cancer should be kept in mind.

Quantitation of alpha-fetoprotein messenger RNA for early detection of recurrent hepatocellular carcinoma: A prospective pilot study

Background: Alpha-fetoprotein (AFP) messenger RNA (mRNA) may be a potential marker of the dissemination of hepatocellular carcinoma (HCC) cells into the circulation. The aim of this prospective pilot study was to assess the prognostic value of quantitative levels of AFP mRNA in patients undergoing ablative treatment for HCC. Methods: Peripheral blood samples were taken from seven patients before and after treatment for measurement of AFP mRNA levels by reverse-transcriptase polymerase chain reaction (RT-PCR). Patients were treated with percutaneous radiofrequency thermal ablation ( n = 3) or transarterial chemoembolization ( n = 4). The level of AFP mRNA in blood was serially determined, and the time course was related to the clinical course and disease outcome. The median duration of follow-up was 14 months (range, 9–16 months). Results: HCC recurred locally in four patients, and lung metastases developed in two of them. Patients were divided into three groups on the basis of the pre- and post-treatment AFP mRNA status. Group 1 included four patients with consistently high serum AFP and AFP mRNA levels (pre- and post-treatment). These patients developed distant and local recurrence. Group 2 included a patient with serum-negative AFP mRNA and normal AFP levels at entry. Although serum AFP remained within normal range, mean AFP mRNA increased from 10 to 95 copies/μg RNA. This patient had no distant metastases, but his tumor markedly increased in size. In Group 3, AFP mRNA and serum AFP remained within normal range before and after treatment. These two patients did not develop either local or distant metastases during the follow-up period. Conclusions: Although this is a small sample size pilot study these findings imply that quantitative measurement of AFP-expressing cells in peripheral blood may serve as a marker of HCC recurrence.

Mixed germ cell tumor of the ovary mimicking unruptured ectopic pregnancy presenting with unusually high serum alpha-fetoprotein level

Malignant germ cell tumors of the ovary constitute fewer than 5% of all ovarian cancers. Malignant mixed germ cell tumors (MMGCTs) may secrete tumor markers including α-fetoprotein (AFP) and β-human chorionic gonadotropin (β-hCG) depending on the type of tumor cells. Because these tumors are almost always seen in the reproductive period, their differential diagnosis with β-hCG secreting ectopic pregnancy is of importance. The patient with MMGCT may present with abdominal pain, vaginal bleeding and pelvic mass similar to an ectopic pregnancy. Here, we present a case of MMGCT, which was referred to our clinic with the admission diagnosis of ectopic pregnancy. However, serum AFP level was exceedingly high (2,172 IU/ml), and transvaginal ultrasonography demonstrated an atypical solid mass 6 cm in diameter. As a result, a hormonally active germ cell tumor of the ovary needed to be considered in the differential diagnosis of ectopic pregnancy.

A tumor in the medulla oblongata producing beta-HCG and AFP

A 23 year-old woman presented with dysarthria, hoarseness, dysphasia, ataxia and dyspnoea. MRI showed a mass of heterogeneous intensity at the dorsal medulla oblongata. Laboratory studies revealed high serum alpha-fetoprotein (AFP) and beta-subunit human chorionic gonadotropin (beta-HCG) levels. No other tumours were found on systemic investigation. An intracranial non-germinomatous germ cell tumour (NGGCT) was strongly suspected. The patient received combination chemotherapy using ifosfamide, cisplatin, and etoposide and local irradiation to a total of 52 Gy. Serum AFP and beta-HCG levels normalized after four cycles of chemotherapy and she became asymptomatic apart from mild postural hypotension. A follow-up MRI showed only a tiny residual lesion in the medulla oblongata, which has been stable for more than three years. Surgical resection should be carefully considered in patients with brainstem tumours with elevation of serum tumour markers as chemo- and radiotherapy may be effective for brainstem NGGCT.

Time-Varying Predictors for Clinical Surveillance of Small Hepatocellular Carcinoma

Prognosis of small hepatocellular carcinoma depends on a constellation of time-varying predictors in association with liver function. We aimed to elucidate the impact of these time-dependent predictors on survival. A total of 108 patients with hepatocellular carcinoma smaller than 5 cm in diameter were recruited. Series of laboratory data and clinical assessments were retrieved from medical records. The time-dependent scoring system for the prediction of death was developed in accordance with a time-dependent Cox regression model. Time trends for biologic predictors parallel cumulative survival of small hepatocellular carcinoma cases. Higher serum alpha-fetoprotein level was identified as the most significant time-dependent predictor. Other significant predictors included aspartate transaminase, bilirubin, alkaline phosphatase, and albumin levels and prothrombin time. Time-dependent surveillance scoring system shows the cutoff points of scores at 6 months, 1 year, 2 years, and 3 years were 42, 21, 19, and 31, respectively; the estimates of sensitivity, 100%, 100%, 100%, and 87.5%, respectively; and the estimates of specificity, 91.26%, 67.02%, 60.27%, and 78.26%, respectively. Predictive validity for this time-dependent Cox regression model, particularly within 1-year of follow-up, is good. The dynamic relationships between time-dependent predictors and risk of death were illustrated. A time-dependent predictive scoring system using these dynamic relationships was developed for real-time surveillance.

Gender difference in clinicopathologic features and survival of patients with hepatocellular carcinoma.

To determine the influence of gender on the clinicopathologic characteristics and survival of patients with hepatocellular carcinoma (HCC). A retrospective analysis of medical records was performed in 299 patients with HCC and their clinicopathologic features and survival were compared in relation to gender. There were 260 male (87%) and 39 female patients (13%), with a male-to-female ratio of 6.7:1. Female patients had lower mean serum bilirubin levels (P=0.03), lower proportion of alcohol abuse (P=0.002), smaller mean tumor size (P=0.02), more frequent nodular type but less frequent massive and diffuse types of HCC (P=0.01), were less advanced in Okuda's staging (P=0.04), and less frequently associated with venous invasion (P=0.03). The median survivals in females (14 mo) were significantly longer than that of male patients (4 mo) (P=0.004, log-rank test). Multivariate analysis demonstrated that high serum alpha-fetoprotein levels, venous invasion, extrahepatic metastasis and lack of therapy were independent factors related to unfavorable prognosis. However, gender did not constitute a predictive variable associated with patient survival. Female patients tend to have higher survival rates than males. These differences were probably due to more favorable pathologic features of HCC at initial diagnosis and greater likelihood to undergo curative therapy in female patients.

Serum and cerebrospinal fluid human chorionic gonadotropin (hCG) and alpha-fetoprotein (AFP) in intracranial germ cell tumors.

We report a retrospective study on serum and cerebrospinal fluid (CSF) alpha-fetoprotein (AFP) and beta-human chorionic gonadotropin (betahCG) determination in a series of 30 patients bearing intracranial germ cell tumors. At diagnosis five patients had high serum and CSF AFP levels. No patient had positive serum AFP and negative CSF AFP or vice versa. Twelve of 30 patients had serum betahCG levels above 5 mlU/mL, eight had high betahCG only in CSF, and ten were completely negative. During treatment and follow-up both markers were accurate indicators of the response to therapy, decreasing rapidly and often becoming normal already after the first phase of treatment. We conclude that these two markers, and mostly betahCG, may be useful in the diagnosis and monitoring of the response to therapy of patients with intracranial germ cell tumors.

Serum and cerebrospinal fluid human chorionic gonadotropin (hCG) and alpha-fetoprotein (AFP) in intracranial germ cell tumors

We report a retrospective study on serum and cerebrospinal fluid (CSF) alpha-fetoprotein (AFP) and beta-human chorionic gonadotropin (betahCG) determination in a series of 30 patients bearing intracranial germ cell tumors. At diagnosis five patients had high serum and CSF AFP levels. No patient had positive serum AFP and negative CSF AFP or vice versa. Twelve of 30 patients had serum betahCG levels above 5 mlU/mL, eight had high betahCG only in CSF, and ten were completely negative. During treatment and follow-up both markers were accurate indicators of the response to therapy, decreasing rapidly and often becoming normal already after the first phase of treatment. We conclude that these two markers, and mostly betahCG, may be useful in the diagnosis and monitoring of the response to therapy of patients with intracranial germ cell tumors.

Association between insulin-like growth factor-2 and metastases after transcatheter arterial chemoembolization in patients with hepatocellular carcinoma

Hypoxia up-regulates insulin-like growth factor-2 (IGF-2) and thus stimulates the growth of hepatocellular carcinoma (HCC) cells. In the current study, the authors prospectively evaluated changes in plasma IGF-2 levels in HCC patients after transcatheter arterial chemoembolization (TACE), which usually results in hypoxic insult to liver tissue. The authors also examined the association between changes in plasma IGF-2 levels after TACE and HCC progression, especially in relation to metastasis. Plasma IGF-2 levels were measured before and 4 weeks after TACE in 46 patients with HCC. Three months after TACE, the patients were evaluated for the occurrence of metastatic HCC. In 13 of the 46 patients, post-TACE plasma IGF-2 levels decreased by > 20% (Group 1) compared with their basal levels; in 18 patients, the IGF-2 levels changed within 20% (Group 2) and in 15 patients the IGF-2 levels increased by > 20% (Group 3). Plasma IGF-2 levels had a tendency to increase in patients with large-sized tumors, high serum alpha-fetoprotein (AFP) levels, and the heterogeneous uptake of iodized oil. Metastatic foci were found in 9 patients in Group 3 (60%), in contrast to only 3 patients in Group 2 (17%) and in none of the patients in Group 1 (P = 0.001). On multivariate analysis, higher Child-Pugh scores and increased plasma IGF-2 levels (Group 3) were found to be independent risk factors for metastasis. Increased plasma IGF-2 levels after TACE, which are common in patients with large-sized tumors and high serum AFP levels, appear to be associated with the occurrence of metastatic HCC after TACE.

Mean arterial pressure, pregnancy induced hypertension, and preeclampsia: Evaluation as independent risk factors and as surrogates for high maternal serum alpha-protein in estimating breast cancer risk.

PURPOSE: Data from a nested case-control study were analyzed to examine high mean arterial pressure (MAP), hypertension of pregnancy and preeclampsia as independent predictors, and as surrogate markers for elevated Alpha-fetoprotein (AFP) levels in evaluating breast cancer risk.METHODS: Cases (n = 205) were identified by the California Cancer Registry from a cohort of pregnant women who were part of the Kaiser Health Plan and took part in the Child Health and Development Studies initiated by the University of California, Berkeley, from June 1959 to September 1966. Controls (n = 337) were selected by randomized recruitment from the same cohort probability matched to cases by distribution of birth dates of cases.RESULTS: High MAP was associated with breast cancer risk, and was different across quartiles of age at first full term pregnancy. Odds Ratios across quartiles were 0.24 (95% CI = 0.08–0.71), 0.84 (95% CI = 0.39–1.66), 1.00 (referent), and 2.50 (95% CI = 1.21–5.13). Neither diagnosed preeclampsia nor hypertension of pregnancy showed any association with breast cancer risk. When both high Alpha-fetoprotein and high mean arterial pressure were entered into the same analysis neither changed the odds ratio for the other more than eight percent. Additionally, AFP level was not a linear function of MAP.CONCLUSIONS: Although the pattern of odds ratios across quartiles of age at first full term pregnancy were similar for the two variables it can not be concluded that high MAP is an adequate surrogate for high levels of maternal serum AFP, but rather represents some related process which is in and of itself a risk factor for breast cancer.

Alpha-fetoprotein levels in maternal serum during pregnancy and maternal breast cancer incidence.

A full-term pregnancy is associated with a reduced risk of breast cancer, but the underlying biologic mechanism has not been elucidated. During pregnancy, maternal serum levels of alpha-fetoprotein, an estradiol-binding protein, rise sharply. In culture, alpha-fetoprotein inhibits the growth of estrogen-sensitive cells, including estrogen-sensitive breast cancer cells. Thus, we investigated whether a high level of alpha-fetoprotein in maternal serum during pregnancy is associated with a reduced risk of breast cancer. From a population-based cohort of 42057 pregnant women in Denmark, enrolled in an alpha-fetoprotein-screening program from 1978 through 1996, we obtained a complete reproductive history, vital status, and a possible diagnosis of breast cancer (in 117 women) to the end of follow-up on September 1, 1998. During pregnancy, women with an alpha-fetoprotein level greater than or equal to the median value had a 41% lower risk of breast cancer than women with an alpha-fetoprotein level below the median value (relative risk [RR] = 0.59; 95% confidence interval [CI] = 0.41-0. 85). RRs for breast cancer by mother's age at childbirth were as follows: 29 years or younger, RR = 0.21 (95% CI = 0.08-0.56); 30-34 years, RR = 0.61 (95% CI = 0.32-1.14); 35-37 years, RR = 0.96 (95% CI = 0.49-1.89); and 38 years or older, RR = 0.71 (95% CI = 0.29-1. 75) (P for trend =.02). Further analyses suggested that high levels of alpha-fetoprotein were associated with a reduced incidence of aggressive disease. The most striking finding was that women with high levels of serum alpha-fetoprotein, compared with women with low levels of serum alpha-fetoprotein, showed a particularly reduced incidence of large tumors (>2 cm; RR = 0.24 [95% CI = 0.11-0.50]). A high level of alpha-fetoprotein in maternal serum during any pregnancy is associated with a low overall incidence of breast cancer and, in particular, with a low incidence of advanced breast cancer at diagnosis. This association appears particularly strong for a pregnancy occurring at a young age.

Levels of maternal serum alpha-fetoprotein (AFP) in pregnant women and subsequent breast cancer risk.

High maternal serum alpha-fetoprotein (AFP) levels during pregnancy may be instrumental in reducing the subsequent risk of breast cancer. This hypothesis was tested in a nested case-control study using stored frozen sera accrued between 1959 and 1966 by the University of California at Berkeley Child Health and Development Studies (CHDS) group from a cohort of pregnant women. Cases with histologically confirmed breast cancer were identified from California Cancer Registry files covering their date of enrollment in the CHDS until 1994. Controls were selected from the CHDS cohort by using randomized recruitment. Third-trimester maternal serum AFP levels were analyzed by using both a radioimmunoassay and an immunoenzymatic method. After controlling for multiple confounders in logistic regression models, the authors found an inverse association between high levels of maternal serum AFP (top quartile) during the index pregnancy and the risk of breast cancer. The protective effect of high levels of maternal serum AFP varied by age at first full-term pregnancy (age 20 years or less: odds ratio (OR) = 0.43, 95% confidence interval (CI) 0.28-0.65; age 21-23 years: OR = 0.62, 95% CI 0.41-0.92). After age 27 years, the estimated risk exceeded unity (OR = 1.67, 95% CI 1.14-2.45). These study findings suggest that some of the protection against breast cancer conferred by early first full-term pregnancy may result from high levels of maternal serum AFP. After age 27 years, a high maternal serum AFP level is not protective and may increase risk.

Flavonoids inhibit estrogen binding to rat alpha-fetoprotein.

There is considerable interest in the role(s) of plant-derived compounds such as bioflavonoids in regulating steroid hormone action in mammals, and in particular, the possible effects of the bioflavonoids on the growth of steroid-dependent breast and prostate tumors and on possible abnormal development of steroid-sensitive tissues. Studies of the hormone-like actions of bioflavonoids often use fetal or neonatal rats, which contain high levels of serum alpha-fetoprotein (AFP), a protein that binds estradiol with a Kd approximately 5 x 10(-9) M. Interaction of bioflavonoids with AFP could affect the availability of estrogens to estrogen-responsive cells, as well as the actions of bioflavonoids. These considerations motivated us to study the effect of several flavonoids (quercetin, rutin, naringenin, chrysin, apigenin, kaempferol, myricetin, morin, fisetin) and isoflavonoids (daidzein, genistein) on estrogen binding to rat AFP. We found that naringenin, a flavanone, and quercetin and kaempferol, flavonols, inhibit estrogen binding to AFP with apparent Kds of about 5 x 10(-7) M. To our surprise, the two isoflavonoids, daidzein and genistein, have Kds of about 5 x 10(-6) M for AFP. This 10-fold [correction of 1Q-fold] difference in affinity for AFP between flavonoids and isoflavonoids suggests that AFP has a specificity for the flavonoid structure. Moreover, the affinities of bioflavonoids for rat AFP are sufficiently high to suggest that flavonoids and isoflavonoids could modulate estradiol and estrone binding to rat AFP in vivo, when present at dietary levels. Additionally, the potency of the plant estrogens may be altered by binding to AFP. The flavonoids that we tested have different hydroxyl and glucoside substituents on the A, B, and C rings, which allows us to define some of the spatial requirements for binding to AFP. We find that 5,7-hydroxyl groups in ring A and a 4'-hydroxyl group in ring B are important for binding to AFP. This information, combined with molecular modeling studies, may elucidate the molecular basis for recognition of flavonoids and estrogens by AFP. Also, these findings indicate that the flavonoid levels in the diet need to be considered in studies of the effects of various xenobiotics and endocrine manipulations on experimental animals, particularly during development when serum estrogen binding protein concentrations are often elevated. Finally, bioflavonoids should be useful tools for understanding the variety of estrogen actions initiated by different structural classes of estrogens.

A CASE OF ALPHA-FETOPROTEIN PRODUCING GASTRIC CANCER SUGGESTIVE OF MULTIPLE DIFFERENTIATION

A case of gastric cancer with high preoperatie serum alpha-fetoprotein (AFP) level was immunohistochemically studied. This study suggested that AFP producing gastric cancer might have an ability to differentiate into various forms. A 60-year-old male with Borrmann type 2 gastric cancer in the antrum showed a markedly high serum AFP level (1610ng/ml). Immunohistochemical study showed the localization of AFP in biopsy specimen, and a subtotal gastrectomy was performed. Further study of the resected specimen revealed the localization of carcinoembryonic antigen (CEA), human chorionic gonadotropin (HCG), endocrine cells (gastrin producing cells) and also AFP in tumor tissue. This study suggested that AFP producing gastric cancer might have an ability to differentiate into various forms. AFP producing gastric cancers are frequently found in advanced cases and most of these cases are accompanied with liver metastasis. The importance of aggressive therapy for the AFP producing gastric cancer must be emphasized.

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The association between maternal serum alpha-fetoprotein and preterm birth, small for gestational age infants, preeclampsia, and placental complications

To determine whether high levels of serum alpha-fetoprotein (AFP) predict increased risk of adverse pregnancy outcomes, including preterm birth (before 37 weeks), preterm birth occurring at or before 28 weeks, small for gestational age (SGA) infant, preeclampsia, and placental abnormalities, and to determine whether low levels of serum AFP predict increased or decreased risk of these outcomes. Using the mother's first name, last name, and zip code, we linked the records of 51,008 women who participated in the California Alpha-Fetoprotein Screening Program between June 15, 1986, and October 31, 1987, with California birth certificates for singleton infants born in 1987. The accuracy of the data linkage was confirmed by manually examining complete names, mother's ethnicity, and mother's age for a sample of 500 of the mother-infant linkages. Blood samples were obtained at 15-19 weeks. A strong gradient of increasing risk of preterm birth with increasing levels of serum AFP was observed (test for trend, P < .01). Among women with high levels of serum AFP (at least 2.5 multiples of the median [MoM]), 24.3% had preterm births, compared with 3.8% of women with low levels of serum AFP (0.81 MoM or less), odds ratio 8.7, 95% confidence interval 7.1-10.7). This gradient persisted when preterm infants of 28 weeks or less were examined separately. Similar gradients were observed for the risk of preeclampsia and placental abnormalities. There was a weaker U-shaped relation between serum AFP level and the risk of an SGA infant. Low levels of second-trimester maternal serum AFP are associated with a very low risk of preterm birth, preeclampsia, and placental complications. High levels of serum AFP are strongly associated with preterm birth, preeclampsia, and placental abnormalities. There is a modest association between AFP levels (both low and high) and SGA birth.

Alpha-fetoprotein-producing adenocarcinoma of the lung

We herein present a case of metachronous primary lung cancers, the first of which was adenosquamous cell carcinoma and the second of which was poorly differentiated adenocarcinoma. At the time the second lung cancer was detected 5 years after being operated on for the first cancer, a high level of serum alpha-fetoprotein (AFP) was noticed, but no elevation of other tumor markers was observed. In addition, no liver metastases, chronic liver diseases or other systemic abnormalities were seen either. The serum AFP level was 696 ng/ml, and the profile of lectin affinity showed a tumor-derived pattern. Two weeks after the operation, the serum AFP level decreased to a normal level. An immunohistochemical analysis confirmed that the exact origin of AFP was the tumor tissue. A specimen taken from the first lung cancer was not stained by the same procedures, which thus indicated this case to be a double primary lung cancer.

Alpha-Fetoprotein

Beginning in 1977, numerous studies have reported an association between high levels of maternal serum alpha-fetoprotein, measured in early pregnancy, and low birthweight and perinatal death. It has been suggested, however, that these findings may be explained by bias. We reviewed 21 studies and found that they were unanimous in reporting this association and that the association cannot be explained by any of the proposed biases. Comparing women whose alpha-fetoprotein levels were 2.5 times the median or more with all other women, the highest relative risk of fetal death was 21.0, with a 95% confidence interval of 8.4-52.2, and the lowest relative risk of fetal death was 4.4, with a 95% confidence interval of 2.8-7.0. For low birthweight (< 2,500 grams), the highest relative risk was 6.4 (95% confidence interval = 3.1-13.1) and the lowest relative risk was 1.9 (95% confidence interval = 1.5-2.5).