The past is prologue: use of serum banks in cancer research.

In this paper, we emphasize the uses of serum banks in cancer research. These include not only case/control studies but also prospective seroepidemiological studies in which the development of a serological marker, such as a viral antibody or viral antigen, can be correlated with the subsequent development of cancer in either an active surveillance program or the use of cancer registries or hospital records. Several different methods of application of the cohort technique are illustrated by studies of hepatitis B antigen and hepatocellular carcinoma and of Epstein-Barr virus in relation to African Burkitt's lymphoma, Hodgkin's lymphoma, and non-Hodgkin's lymphoma. Collections of sera done for one purpose can often be utilized for another purpose, if properly stored and documented. Two examples are tests for human T-cell leukemia virus, type 1, antibody from sera done for a health survey in Barbados approximately 8 years earlier and the use of data determined for a prospective study of the incidence of Epstein-Barr virus infection and infectious mononucleosis in West Point Cadets for psychological factors affecting the development of clinical illness among those infected. Archival materials, such as frozen tissues and paraffin sections, may also now be utilized for identifying genomes of potential oncogenic viruses by the polymerase chain reaction.

Viruses other than HIV and non-Hodgkin's lymphoma.

There are several viral infections which are known to cause lymphoma among animals; all establish latency in lymphoid cells. The human T-lymphotropic virus type I is a human virus which causes lymphomas among a subset of carriers. However, this virus is very restricted in its distribution and as such, is unlikely to play a role in the increase of non-Hodgkin's lymphoma (NHL). A highly prevalent infection, the Epstein-Barr virus (EBV) is known to play a role in the etiology of NHL among persons with acquired or inherited immune suppression. However, whether it is involved with "spontaneous" NHL is unknown. We have found evidence that among a group of 104 NHL patients with blood samples taken several years before diagnosis, there was an alteration in the antibody profile against the EBV which is quite similar to that seen for immune-suppressed patients prior to their diagnosis. This pattern is most evident in the oldest patients. This suggests that there may be an age-related subclinical immune suppression leading to chronic activation of EBV. If a viral infection is a major factor in the recent increase in NHL in the world, then we should consider the role of immune-suppressive exposures which have become widespread in recent decades.

Changes in hematologic parameters among Japanese HTLV-I carriers.

Hematologic data from 1,039 persons who participated in the Miyazaki Cohort study on human T-cell lymphotropic virus type-I (HTLV-I) infection were analyzed. Individuals were classified by HTLV-I antibody status and the presence of abnormal lymphocytes (Ably). We identified several differences in selected leukocyte populations: lymphocyte percent was higher among the HTLV-I carriers with Ably (36.5 +/- 2.0%, n = 29) compared with the carriers without Ably (33.1 +/- 0.6%, n = 299) and the seronegatives 36.4 +/- 0.4%, n = 711) (p = 0.04). Conversely, there was a trend of decreasing eosinophil percent among both carrier groups with the lowest percent among carriers with Ably (1.8 +/- 0.5%) compared with the seronegatives (2.8 +/- 0.1%) (p = 0.05). Mean basophil percent was decreased among both carriers groups (p = 0.09). Additionally, red cell count was elevated among the carriers with Ably (461 +/- 7 x 10(4)/mm3) compared with the seronegatives (446 +/- 2 x 10(4)/mm3) (p = 0.03). The HTLV-I carriers with Ably had lower serum albumin (4.39 +/- 0.05 g%) compared with the seronegatives (4.47 +/- 0.01 g%) (p = 0.10). These alterations may be a consequence of HTLV-I infection, with the greatest changes among carriers with Ably, a subset thought to be at risk for developing adult T-cell leukemia.

HIV-1 seropositivity and behavioral and sociological risks among homosexual and bisexual men in six Mexican cities.

We report on the epidemiology of sexual behaviors, HIV-1 seroprevalence, and condom use in gay and bisexual men in six Mexican cities in 1988 and test the extent to which variations in sexual behavior and sociological risks are responsible for variations in prevalence. Seroprevalence rates among samples in six cities ranged from 2% to 25%. In multiple logistic regression models controlling for city, insertive/receptive behavior (IRB), and meeting partners in bathhouses, the following were independently related to seropositivity (p less than 0.05): city, IRB, syphilis, sex with a person with AIDS, and meeting partners in bathouses. The independent risks associated with categories of IRB were no or almost no activity (odds ratio 1.0), only insertive (3.0), mostly insertive (4.9), mixed (6.0), mostly receptive (3.3), and only receptive (0.9). The condom use rate on last sexual encounter was 30%. The main sexual risk for HIV-1 infection is not exclusively receptive anal sex, but rather mixed behavior. This association may be explained by the infectious state of the partner pools. The sociologic risk variables (national and local partner pools) are better predictors of seroprevalence than behavioral variables, such as the number of partners or use of condoms. These results imply that more effective individual strategies for risk reduction are needed, including better knowledge concerning the risk status of partners.

The distribution of T-cell subsets among HTLV-I carriers in Japan.

Data on T-cell subsets from 89 human T-cell lymphotropic virus-I (HTLV-I) carriers and 25 seronegative people were analyzed to identify differences in T-cell subset values among three subgroups: HTLV-I carriers with abnormal lymphocytes (Ably; n = 24), carriers without Ably (n = 65), and HTLV-I seronegatives (n = 25). Estimates of mean values were adjusted for age, sex, smoking, and alcohol drinking, as appropriate. The percentage of CD25+ T cells was elevated in carriers with Ably (mean, 16.7 +/- 1.0) compared with the seronegatives (11.4 +/- 1.4; p = 0.0002); individuals with CD25 T-cell percentages above the median for the seronegatives had a corresponding 5.4-fold risk for being a carrier with Ably. Similarly, the percentage of CD4 T cells was elevated in carriers with Ably. Conversely, the percentage of CD8 T cells was lower among both groups of HTLV-I carriers than in the seronegatives. There was a corresponding significant increase (p = 0.0004) of the CD4/CD8 ratio among carriers with Ably (1.57 +/- 0.12) compared with the seronegatives (1.22 +/- 0.12). Among subjects with CD4/CD8 ratios above the median for the seronegatives, there were 6.8- and 4.5-fold risks for being carriers with or without Ably, respectively. The percentage of CD7 was lower among carriers with Ably (75.6 +/- 1.6) than among seronegatives (78.9 +/- 1.5; p = 0.13). The percentage of beta-interleukin-2-receptor-positive T cells did not vary among the three subgroups.(ABSTRACT TRUNCATED AT 250 WORDS)

Viruses and cancer. Causal associations.

This review first considered some general problems in establishing causal links between a virus and a human cancer and offered some guidelines in the pursuit of this objective. Second, it reviewed the current causal associations for several candidate oncogenic viruses in relation to the tumors with which they are associated. These include Epstein-Barr virus in relation to Burkitt's lymphoma, nasopharyngeal carcinoma, Hodgkin's disease, and non-Hodgkin's lymphoma; hepatitis B and C viruses in relation to hepatocellular carcinoma; human T-cell leukemia/lymphoma virus type 1 and atypical leukemia/lymphoma; and human papilloma viruses in relation to cervical carcinoma. For some, the causal relationship is strong: hepatitis B virus with hepatocellular carcinoma, and human T-cell leukemia/lymphoma virus with adult T-cell leukemia/lymphoma. For one, the causal relationship is moderate: Epstein-Barr virus with African Burkitt's lymphoma. For others it is incomplete or inconclusive: Epstein-Barr virus with Hodgkin's disease and non-Hodgkin's lymphoma, and hepatitis C virus with hepatocellular carcinoma. Current techniques do not permit an answer for some: human papilloma virus with cervical carcinoma.

The minimum number of clones necessary to sequence in order to obtain the maximum information about hepatitis C virus quasispecies: a comparison of subjects with and without liver cancer.

Most studies of hepatitis C virus (HCV) quasispecies have reported the results of sequencing only three to five clones per sample. The possibility that sequencing so few clones might not provide a representative picture of the quasispecies present in a sample has never been evaluated. The present study was conducted to evaluate whether sequencing greater numbers of clones results in better information about the HCV quasispecies number and distribution, and to compare the HCV quasispecies in liver cancer cases and controls. RNA was extracted from serial serum samples from six subjects with HCV-associated liver cancer and 11 age- and sex-matched HCV-infected controls without liver cancer. The hypervariable region 1 (HVR1) of the HCV genome was amplified, cloned, and sequenced. For further studies of 12 serum samples from two liver cancer cases and two matched controls, successive groups of 10 additional clones were sequenced up to a total of 50 clones per serum sample. When only 10 clones were sequenced from each specimen, no consistent differences were seen between the number of HCV quasispecies in the six liver cancer cases and the 11 controls. However, sequencing 40 clones from each of 12 samples from two liver cancer cases and two controls revealed a greater number of quasispecies in liver cancer cases than in controls. Testing an additional 10 clones (50 clones per sample) did not significantly increase the number of quasispecies detected.

Methods for inference on transmission in seroprevalence data for multiple infections.

When risk factors for an infectious disease are unknown, a method commonly employed is to investigate parallels with known infections (covariate infections). Data sets of value here are those for specified populations in which the seroprevalence of antibodies for multiple infections has been ascertained. The use of markers of covariate infections in multivariable analyses is problematic when the covariate infection is not itself an independent risk factor for the outcome of interest. In the performance of these analyses, the authors recommend the following strategy: 1) For estimates of the effects of measured risk factors on the outcome, adjustment for the covariate infection should not be done; this will avoid problems of overadjustment. 2) After control for the measured risk factors, an estimate of the "effect" of the covariate infection may be used as an indicator of the presence of unmeasured shared risk factors. 3) When shared, measured risk factors exist, the authors propose the use of methods developed for analysis of repeated measures of categorical variables to assist in inference about shared mechanisms of action of these risk factors. This analytic strategy takes advantage of the method of analogy for building understanding of transmission of new agents through their parallels with better known ones and is useful in the development of hypotheses.

Evaluation of morbidity among human T lymphotropic virus type 1 carriers in Miyazaki, Japan.

Morbidity associated with human T lymphotropic virus type I (HTLV-I) infection was investigated in a Japanese population within an area in which HTLV-I infection is endemic. Of 1824 subjects enrolled in the Miyazaki Cohort Study between November 1984 and May 1991, 500 (27.4%) were seropositive for HTLV-I antibodies. As expected from previous studies, HTLV-I positively appeared to be associated with baseline history of anemia (adjusted odds ratio [OR]= 1.3; 95% confidence interval [CI]= 0.99-1.7) and kidney disease (OR=1.6; 95% CI= 0.91-2.9); a positive association also was noted for asthma in men (OR=3.4; 95% CI=1.2-9.8). Unanticipated findings included a relationship between HTLV-I infection and cardiac disease history (OR=1.4; 95% CI=0.94-2.2; HTLV-I carriers also were more likely to have an abnormal electrocardiogram at baseline (OR=1.5; 95% CI=1.2-1.9). Furthermore, an apparent protective effect for ulcers (OR=0.62; 95% CI=0.40-0.95) and diabetes (OR=0.49;95% CI=0.22-1.1) was observed. HTLV-I infection may modify the risk of specific disease outcomes by altering host immune function.

Evaluation of a population roster as a source of population controls: the Massachusetts Resident Lists.

Published population rosters can serve as a convenient source of population controls. The authors evaluated one such roster, the Massachusetts Resident Lists, by estimating the completeness of the Lists and by describing the differences between persons included and not included on the Lists. The subjects were cases from three case-control studies of ovarian cancer conducted in eastern Massachusetts between 1978 and 1996. For each of the three case series, more than 90% of the cases were located on the Resident Lists. Age was one of the primary differences to emerge between cases included and not included; in the most recent case series, cases younger than age 40 years were less likely than older cases to be included on the Lists.

HCV infection and liver cancer mortality in a Japanese population with HTLV-I.

In a cohort study of human T-lymphotropic virus type I (HTLV-I) infection in Japan, 10 cases of liver cancer death occurred from 1984 through 1993. To analyze the role of hepatitis C virus (HCV), which has been associated with an increasing incidence of hepatocellular carcinoma (HCC) in Japan, a nested case-control study was performed. Five of the 10 liver cancer cases were positive for antibody to HTLV-I (anti-HTLV-I). The possible interaction between HCV and HTLV-I infections in the etiology of HCC was investigated, with each liver cancer case matched to 5 cohort controls by gender, age, serum sample date and anti-HTLV-I status. Using a matched analysis odds ratio (OR) were generated for the relationship between HCV serologic status and death liver cancer. Based on second-generation enzyme immunoassay with confirmation by recombinant immunoblot assay, 8 of 9 cases with adequate serum available (89%) and 9 of 50 (18%) controls were found to be positive for antibody to HCV (anti-HCV). Liver cancer death was highly associated with anti-HCV (matched OR = infinity; p < 0.001). Anti-HTLV-I seroprevalence was some what correlated with HCV infection. However, the high risk of liver cancer death observed for anti-HCV-positive Individuals in this population did not vary with respect to whether or not the subjects were also infected with HTLV-I.

Gender difference in skin reactivity to purified protein derivative among carriers of HTLV-I in Japan.

The incidence of malignancies due to oncogenic virus infections tends to be higher in men than in women. Gender-related differences in cell-mediated immunity, which plays a role in viral pathogenesis, may explain this observation. To explore this possibility in the context of HTLV-I infection, we examined skin reactivity to purified protein derivative (PPD) among 128 residents of an HTLV-I endemic area in Japan, who were born before 1921 and are assumed to have been exposed to M. tuberculosis bacilli. The odds ratio (OR) for reduced PPD reactivity (erythema <10 mm in diameter) was calculated by multiple logistic regression analysis. Men were significantly less likely than women to have reduced PPD reactivity among HTLV-I-negative individuals (26% versus 59%; p < .01); whereas this gender difference was not apparent among HTLV-I carriers (63% versus 62%; p = .87). HTLV-I positivity was strongly associated with reduced PPD reactivity in men, but not in women (odds ratio [OR], 7.3 versus 1.2; p = .05). Although this observation may be due, in part, to a longer average duration of HTLV-I infection in men compared with women, the finding also raises the possibility that men may be inherently more susceptible to loss of PPD reactivity by HTLV-I infection.

Sex-specific mortality from adult T-cell leukemia among carriers of human T-lymphotropic virus type I.

Perinatal infection with human T-lymphotropic virus type I (HTLV-I) is considered a risk factor for adult T-cell leukemia (ATL). Incidence of ATL in Japan is generally higher in males compared with females, perhaps partly due to an earlier average age of infection among males. We estimated sex-specific ATL mortality among perinatally-infected HTLV-I carriers in the prospective Miyazaki Cohort Study in Japan. Based on the approximated proportion of perinatally-infected carriers, the relative risk (RR) of ATL for males compared with females was calculated. Six ATL deaths (4 males, 2 females) occurred among the 550 HTLV-I carriers in the cohort during 13 years of follow-up. The overall ATL mortality was 190.5 (95% CI 51.9-487.7) per 10(5) person-years for males and 51.7 (6.3-186.8) per 10(5) person-years for females (age-standardized RR = 3.9, p=0.02). By approximating the number of persons who acquired infection perinatally, the estimated mortality among those perinatally-infected HTLV-I carriers was 209.1 (57.0-535.2) per 10(5) person-years for males and 60.9 (7.4-219.9) per 10(5) person-years for females (age-standardized RR = 3.7, p=0.02). The adjusted RR changed minimally from the unadjusted RR, suggesting that earlier age of infection alone is unlikely the explanation for the male predominance in ATL. Based on the small number of cases available for analysis, aspects of gender itself appear to play a role in the development of this malignancy.

Heterosexual transmission of human T cell leukemia/lymphoma virus type I among married couples in southwestern Japan: an initial report from the Miyazaki Cohort Study.

To identify factors that may modify the heterosexual transmission of human T cell leukemia/lymphoma virus type I (HTLV-I), 534 married couples enrolled in the Miyazaki Cohort Study between November 1984 and April 1989 were studied: 95 husband HTLV-I-seropositive (H+)/wife seropositive (W+), 33 H+/W-, 64 H-/W+, and 342 H-/W-. After 5 years of follow-up, seven seroconversions occurred and clustered significantly among serodiscordant pairs (relative risk [RR] = 41.2); the rate of transmission was 3.9 times higher if the carrier spouse was male (P = .19). Among H+/W- couples, husband's age > or = 60 years strongly predicted seroconversion in the wives (RR = 11.5). All 4 carrier husbands whose wives seroconverted had HTLV-I titers > or = 1:1024 (P = .04) and were anti-tax antibody positive (P = .06). In cross-sectional analysis, total parity also was independently associated with wife's serostatus but only length of marriage with husband's. Overall, sexual transmission of HTLV-I was primarily from older infected husbands to their wives, with husbands' viral status being an important factor.

Human immunodeficiency virus infection in Mexico City. Rectal bleeding and anal warts as risk factors among men reporting sex with men.

The objectives of this study were to evaluate the frequency and determinants of rectal bleeding and the association between rectal bleeding and risk of human immunodeficiency virus (HIV) infection among homosexual/ bisexual men in Mexico City. Men who requested anonymous HIV testing at a public clinic in Mexico City and who reported engaging in any homosexual behavior were eligible to participate in this study. Trained staff collected information on demographic factors, sexual behavior, psychological states, and HIV serostatus from all consenting, eligible clients. Logistic regression modeling was used to investigate the independent effect of risk factors among 2,758 men who were tested between June 1991 and December 1992. Bleeding during anal intercourse was a common occurrence: More than one third of the men in the study reported some bleeding, and 8% reported bleeding in half or more of their intercourse episodes. The prevalence of HIV infection among bleeders was 42% as compared with 28% in nonbleeders (p < 0.0001), and the adjusted odds ratio was 1.8 (95% confidence interval (CI) 1.1-2.8) for men who bled in more than half of their anal intercourse episodes relative to nonbleeders. There was a trend of increasing HIV seroprevalence with increasing frequency of rectal bleeding (p = 0.001). Nine percent of all HIV infections and 42% of infections among frequent bleeders were attributable to rectal bleeding. Men who reported both rectal bleeding and anal warts were 3.5 (95% CI 2.1-5.8) times more likely to be HIV-infected in multivariate analysis than men reporting neither rectal bleeding nor anal warts. Determinants of rectal bleeding included older age, more education, more receptive anal intercourse than insertive intercourse, receptive digital-anal contact, anal warts, and genital ulcers. Among men reporting sex with men in Mexico City, rectal bleeding is common. It is an independent risk factor for HIV infection, and warrants attention in acquired immunodeficiency syndrome prevention efforts. Rectal bleeding that results from rupture of anal warts may be an especially effective portal of HIV transmission.

PIP: During June 1991 to December 1992, 68.8% of all men who gave informed consent for HIV testing at a public health clinic in Mexico City and for participation in this study had ever had sexual intercourse with men. The final sample size was 2758 men. The study examined the reported frequency of rectal bleeding, the determinants of rectal bleeding, and the interactions between rectal bleeding and other risk factors with HIV infection among homosexual/bisexual men. It also aimed to determine whether rectal bleeding is an independent risk factor for HIV transmission. 32.8% had HIV infection. 39% reported some rectal bleeding during anal intercourse. 8% experienced rectal bleeding during at least 50% of intercourse episodes. Overall, bleeders were more likely to be HIV infected than nonbleeders (42% vs. 28%; p 0.0001; adjusted odds ratio [AOR] = 1.8 for men who bled in more than 50% of anal intercourse episodes; AOR = 1.3 for men who sometimes bled). The odds ratios increased as the frequency of reported rectal bleeding increased (p = 0.001). Condom use during receptive anal intercourse did not affect the association between rectal bleeding and HIV infection. 9% of all HIV infections were attributable to rectal bleeding. 42% of HIV infections among bleeders were attributable to rectal bleeding. In the multivariate analysis, men with both rectal bleeding and anal warts were more likely to have HIV infection than men who had neither (67.9% vs. 27.2%; AOR = 3.5). Significant predictors of rectal bleeding were older age (i.e., =or 30) (AOR = 1.5), more education (AOR = 1.4-1.5), more receptive anal intercourse than insertive intercourse (AOR = 5.3-16.1), receptive digital-anal contact (AOR = 1.6), anal warts (AOR = 1.9), and genital ulcers (AOR = 2). These findings show that rectal bleeding is an independent risk factor for HIV infection. Rupture of anal warts is an especially effective portal of HIV transmission.

Risk factors for adult T-cell leukemia among carriers of human T-lymphotropic virus type I.

The presence of circulating "flower cells" and a low prevalence of antibody to Tax regulatory protein of human T-lymphotropic virus type I (HTLV-I) are characteristics of adult T-cell leukemia (ATL). To examine the predictability of levels of HTLV-I antibodies and of flower cell-like abnormal lymphocytes (Ably) for the risk of ATL among asymptomatic HTLV-I carriers, we prospectively evaluated the levels of viral markers of five HTLV-I carriers who developed ATL and 38 age-, sex-, and screen-matched HTLV-I-positive controls in the Miyazaki Cohort Study. After accounting for matching factors, Ably level was slightly, but not significantly, higher among cases than among controls (P =.13). Anti-HTLV-I (odds ratio [OR] = 1.6 per twofold dilution; 95% confidence interval [CI] 0.94, 3.8) was associated with ATL diagnosis, but antibody to Tax regulatory protein (anti-Tax) was not (OR = 0.78; 95% CI 0.26, 1.7). Anti-Tax level was low for all ATL cases for up to 10 years preceding their diagnosis, independent of the level of anti-HTLV-I titer. HTLV-I carriers with a higher anti-HTLV-I titer and a lower anti-Tax reactivity may be at greatest risk of ATL.

Predictors of level of circulating abnormal lymphocytes among human T-lymphotropic virus type I carriers in Japan.

Human T-lymphotropic virus type I (HTLV-I) carriers often have abnormal lymphocytes (Ably) that resemble malignant cells of adult T-cell leukemia (ATL). To identify predictors of the level of Ably in a longitudinal study of asymptomatic HTLV-I carriers, we analyzed data from 215 subjects (67 men and 148 women) with multiple Ably measurements on blood smears. Ably+ (those having Ably > 0.6% of leukocytes counted on a blood smear at least once) was strongly associated with a high proviral load (OR 8.9; 95% CI 4.1, 19.5). The association among those defined as Ably++ (Ably > 0.6% at all screens or Ably > 1.6% at least once) was higher (19.7; 6.9, 56.1). Ably++ was also significantly associated with male gender (2.8; 1.0, 7.8). Multivariate analysis of Ably level indicates that men with a high proviral load, high anti-HTLV-I titer and low anti-Tax reactivity have the highest Ably level.

Occupational exposure to human immunodeficiency virus (HIV) and hepatitis B virus (HBV) among embalmers: a pilot seroprevalence study.

We performed a serosurvey of 133 embalmers in an urban area where human immunodeficiency virus (HIV) infection is prevalent. Although we found histories of needlesticks to be common, and the seropositivity rate of hepatitis B virus (HBV) (13%) was approximately twice that of a blood donor comparison group, HIV antibody was uniformly absent in 129 embalmers who denied HIV risk factors, and present in one of four with self-described risk behaviors. The risk of HBV infection was higher among embalmers who have worked more than 10 years, relative risk (RR) 16.2 (95% confidence interval 2.1, 126.5), did not routinely wear gloves, RR 9.8 (CI 3.4, 28.5), or are employed in the city of Boston, RR 4.7 (CI 1.8, 12.0).