The 15-Country Collaborative Study of Cancer Risk among Radiation Workers in the Nuclear Industry: estimates of radiation-related cancer risks

A 15-Country collaborative cohort study was conducted to provide direct estimates of cancer risk following protracted low doses of ionizing radiation. Analyses included 407,391 nuclear industry workers monitored individually for external radiation and 5.2 million person-years of follow-up. A significant association was seen between radiation dose and all-cause mortality [excess relative risk (ERR) 0.42 per Sv, 90% CI 0.07, 0.79; 18,993 deaths]. This was mainly attributable to a dose-related increase in all cancer mortality (ERR/Sv 0.97, 90% CI 0.28, 1.77; 5233 deaths). Among 31 specific types of malignancies studied, a significant association was found for lung cancer (ERR/Sv 1.86, 90% CI 0.49, 3.63; 1457 deaths) and a borderline significant (P = 0.06) association for multiple myeloma (ERR/Sv 6.15, 90% CI <0, 20.6; 83 deaths) and ill-defined and secondary cancers (ERR/Sv 1.96, 90% CI -0.26, 5.90; 328 deaths). Stratification on duration of employment had a large effect on the ERR/Sv, reflecting a strong healthy worker survivor effect in these cohorts. This is the largest analytical epidemiological study of the effects of low-dose protracted exposures to ionizing radiation to date. Further studies will be important to better assess the role of tobacco and other occupational exposures in our risk estimates.

Risk of cancer after low doses of ionising radiation: retrospective cohort study in 15 countries

OBJECTIVES

To provide direct estimates of risk of cancer after protracted low doses of ionising radiation and to strengthen the scientific basis of radiation protection standards for environmental, occupational, and medical diagnostic exposures.

DESIGN

Multinational retrospective cohort study of cancer mortality.

SETTING

Cohorts of workers in the nuclear industry in 15 countries.

PARTICIPANTS

407 391 workers individually monitored for external radiation with a total follow-up of 5.2 million person years.

MAIN OUTCOME MEASUREMENTS

Estimates of excess relative risks per sievert (Sv) of radiation dose for mortality from cancers other than leukaemia and from leukaemia excluding chronic lymphocytic leukaemia, the main causes of death considered by radiation protection authorities.

RESULTS

The excess relative risk for cancers other than leukaemia was 0.97 per Sv, 95% confidence interval 0.14 to 1.97. Analyses of causes of death related or unrelated to smoking indicate that, although confounding by smoking may be present, it is unlikely to explain all of this increased risk. The excess relative risk for leukaemia excluding chronic lymphocytic leukaemia was 1.93 per Sv (< 0 to 8.47). On the basis of these estimates, 1-2% of deaths from cancer among workers in this cohort may be attributable to radiation.

CONCLUSIONS

These estimates, from the largest study of nuclear workers ever conducted, are higher than, but statistically compatible with, the risk estimates used for current radiation protection standards. The results suggest that there is a small excess risk of cancer, even at the low doses and dose rates typically received by nuclear workers in this study.

An empirical approach to the statistical analysis of mutagenesis data from the Salmonella test

A number of recent papers have suggested basing the statistical analysis of Salmonella (Ames) mutagenicity test results on a mathematical model of the complete dose-response curve. For most mutagens at low doses the curve increases linearly; then, as the dose increases, the curve may flatten and finally turn downwards due primarily to effects of toxicity. The exact mechanism underlying this shape is, however, not well understood and is likely to vary for different chemicals. A different approach is to assume that the initial part of the curve is linear and to base the statistical analysis solely on this region, reasoning that it contains most of the interpretable information about the mutagenesis dose response. In this paper a formal method of deciding which points are on the initial linear part of the curve is described, and a statistical method is proposed for analyzing these points. Computer simulations are used to examine the properties of the procedure and comparisons are made with a previously proposed mathematical model of the whole curve. It is concluded that the method suggested here provides a very satisfactory, robust method for the standard analysis of Salmonella data.

Nutritional factors in colorectal cancer risk: a case-control study in Majorca

The relationship between energy intake, selected nutrients and colorectal cancer was investigated in the population of Majorca, a Spanish island in the Mediterranean basin. A population-based case-control study using food frequency questionnaires was conducted during the period 1984-1988 and included 286 cases of colorectal cancer, 295 population controls and 203 hospital controls. Food composition tables and ad-hoc estimates of portion sizes were used to derive intake estimates of 29 nutrients and of total calories. Relative risks were calculated for quartiles of consumption of each specific nutrient after adjustment for total calorie intake. Colorectal cancer was found associated with dietary intake of total calories (RRs = 1.0, 1.6, 1.6, 2.6) and cholesterol (RRs = 1.0, 0.9, 1.7, 1.7) and a protective effect was associated with the intake of fibre from legumes (pulses) and folic acid. The associations and the trends were statistically significant. Among the main energy-supplying nutrients, after adjustment for calories from other sources, increased risks were found for protein (RRs = 1.0, 1.1, 1.7, 2.5), notably animal protein, and carbohydrates (RRs = 1.0, 1.5, 1.4, 2.2), whereas no effects were found for increased consumption of lipids or saturated fats.

Surgical treatment and risk of sporadic Creutzfeldt-Jakob disease: a case-control study

BACKGROUND

Apart from the small number of iatrogenic and familial cases, the cause of most cases of Creutzfeldt-Jakob disease (CJD) is not known. We aimed to identify risk factors for sporadic CJD.

METHODS

In a case-control study, we compared the medical history and selected demographic characteristics of 241 definite (neuropathologically confirmed) and probable (clinically likely) patients with CJD, ascertained from the Australian National Creutzfeldt-Jakob Disease Registry between Jan 1, 1970, and October 31, 1997, and of 784 controls, recruited from the community by random telephone interview in August, 1997. Standard logistic regression was used for the comparisons.

FINDINGS

Surgical procedures were significantly associated with the development of sporadic CJD. This risk progressively increased with the number of surgical treatments to a maximum for three procedures (odds ratio 2.13 [95% Cl 1.34-3.41], p=0.002). There was also a significant association between risk of CJD and residence or employment on a farm (p<0.001) or market garden (p=0.002) for longer than 10 years. We found no significant risk associated with a history of blood transfusion, organ transplantation, major dental work, or occupation.

INTERPRETATION

Our findings accord with the hypothesis that a range of surgical treatments may serve as unrecognised contamination events and account for a proportion of cases of sporadic CJD. Possible biases in different methods and times for the acquisition of data on cases and controls suggest our findings need to be replicated in independent studies with community controls.

Long-term symptomless HIV-1 infection in recipients of blood products from a single donor

There have been reported cases of long-term symptomless human immunodeficiency virus type 1 (HIV-1) infection, but it is not clear whether the benign course of infection was due to host, viral, or other unknown factors. During follow-up of subjects with transfusion-acquired HIV-1 infection in New South Wales, Australia, we identified a group of 6 subjects who had been infected through a single common donor. We were therefore able to study the contributions of various factors to the course of infection. Throughout follow-up (range 6.8-10.1 years after infection), 5 of the recipients and the donor (last follow-up 10.2 years after infection of the first recipient) remained clinically free of symptoms, with normal CD4 cell counts and no p24 antigenaemia. HIV-1 was isolated from only 1 recipient; the isolate did not induce syncytia in a SUPT1 co-culture assay and had a limited in-vitro host range. 1 infected recipient (who had received extensive immunosuppressive treatment for systemic lupus erythematosus) developed Pneumocystis carinii pneumonia and died 4.3 years after infection. The frequency of progression to AIDS or a CD4 cell count below 0.50 x 10(9)/l was significantly lower among the 6 subjects with a common donor (1/6) than among 101 other HIV-infected transfusion recipients for whom data from 7 years of follow-up were available (94/101; p less than 0.0001). These findings suggest that the subjects were infected by a less virulent strain of HIV-1. The identification of this group of subjects should stimulate a search for other similar groups, which will provide important information on the immunopathogenesis of HIV-1 disease.

A population-based case-control study of colorectal cancer in Majorca. I. Dietary factors

A population-based case-control study was conducted between July 1984 and February 1988 in the Spanish island of Majorca; 286 incident colorectal cancer cases, 295 population controls and 203 hospital controls were interviewed using a food frequency questionnaire. In a multivariate analysis, an increased risk of colon cancer was found for high consumption of fresh meats (RR = 2.87) while a high consumption of cruciferous vegetables afforded protection (RR = 0.48). For rectal cancer an increased risk was associated with dairy products (RR = 3.08) while a protection was afforded by consumption of cruciferae (RR = 0.50). For colorectal cancer, the cereal food group also showed an increase in risk (RR = 1.92). When cases were compared to hospital controls, the effects of cruciferae in colon and rectum and those of dairy products in rectal cancer remained. The magnitude of the RR estimates was decreased for most comparisons, although in general terms the direction of the associations was the same. In addition, univariate analyses of food groups also suggested significant increases in risk of colorectal cancer for increasing consumption of cereals, potatoes, pastry, eggs and number of meals per day. An indication was found of a reduction in risk for consumers of coffee. An analysis based on risk scores was also conducted and a 4-fold increase in the risk of colorectal cancer and a highly significant statistical trend was found for high consumption of fresh meat, dairy products and cereals combined with low consumption of cruciferae.

Guillain-Barré syndrome and Campylobacter jejuni: a serological study

The association between Campylobacter jejuni infection and Guillain-Barré syndrome was investigated serologically in a retrospective study of 56 patients admitted to this hospital over four years. Evidence of preceding C jejuni infection was found in 21 (38%) of these patients, indicating that C jejuni was the most common single identifiable pathogen precipitating the disease. Among those patients who had presented with preceding diarrhoea the serum antibody response was similar to that in uncomplicated C jejuni enteritis. Patients with serological evidence of preceding C jejuni infection manifested a significantly more severe form of the disease. In cerebrospinal fluid the predominant specific antibody class was IgG, and this was closely related to the serum titres of specific IgG. IgA and IgM specific antibodies were found only in the cerebrospinal fluid of patients with recent C jejuni infection. These findings support the possibility that humoral immune factors are responsible for the neural damage and demyelination seen in Guillain-Barré syndrome.

Aflatoxin exposure, hepatitis B virus infection and liver cancer in Swaziland

A study was carried out in Swaziland to assess the relationship between aflatoxin exposure, hepatitis B infection, and the incidence of liver-cell carcinoma, which is the most commonly occurring malignancy among males in Swaziland. Levels of aflatoxin intake were evaluated in dietary samples from households across the country, and crop samples taken from representative farms. Prevalence of hepatitis B markers was estimated from the serum of blood donors, and liver cancer incidence was recorded for the years 1979-83 through a national system of cancer registration. Across 4 broad geographic regions, there was a more than 5-fold variation in the estimated daily intake of aflatoxin, ranging from 3.1 to 17.5 micrograms. The proportion of HBV-exposed individuals was very high (86% in men), but varied relatively little by geographic region; the prevalence of carriers of the surface antigen was 23% in men, and varied from 21 to 28%. Liver cancer incidence varied over a 5-fold range, and was strongly associated with estimated levels of aflatoxin. In an analysis involving 10 smaller subregions, aflatoxin exposure emerged as a more important determinant of the variation in liver cancer incidence than the prevalence of hepatitis infection. Aflatoxin estimates from crop samples appeared to be a reasonable surrogate for dietary measurements. A comparison with dietary aflatoxin levels measured in an earlier survey in Swaziland suggested that programmes aimed at reducing contamination levels had had some success.

HIV lipodystrophy: prevalence, severity and correlates of risk in Australia

OBJECTIVE

To establish the prevalence, severity and factors associated with the HIV lipodystrophy syndrome.

METHODS

Cross-sectional study of lipodystrophy conducted in high HIV caseload primary care sites and HIV outpatient clinics. A subset of patients was examined using dual energy X-ray absorptiometry (DEXA) and single cut abdominal computerized tomography (CT) at the L4 vertebral level to quantify regional and total body fat. Factors associated with lipodystrophy, lipoatrophy and lipohypertrophy were assessed using multiple logistic regression based on assignment of cases and non-cases.

RESULTS

One thousand, three hundred and forty-eight patients (95% male) were surveyed, 20% had AIDS, the mean CD4 lymphocyte count was 486 cells/microL, and 55% had <500 HIV-1 RNA copies/mL. Most participants (87%) had previously received or were currently receiving combination antiretroviral therapy, 73% with at least one protease inhibitor (PI) and 14% a non-PI-containing regimen. Lipodystrophy prevalence was 53% and of these, 55% reported both peripheral lipoatrophy and central lipohypertrophy, 31% experienced peripheral lipoatrophy only and 14% had central lipohypertrophy only. The prevalence of any body habitus change was 62% in PI-experienced patients, 33% in PI-naive patients and 21% in antiretroviral-naive patients. Lipodystrophy severity was less in antiretroviral-naive patients and most severe in PI-experienced patients. Increasing severity of lipodystrophy was both positively and significantly correlated with elevated liver enzymes, decreased testosterone levels, decreased skin-fold thickness, lower levels of total and peripheral fat (DEXA) and higher levels of visceral fat (CT). Lipodystrophy was also significantly associated with increasing age, symptomatic HIV disease, effective viral suppression, and increasing duration of therapy with both nucleoside reverse transcriptase inhibitors and PIs.

CONCLUSIONS

The prevalence and severity of lipodystrophy reflects both length and type of treatment with antiretroviral therapy and is associated with decreased testosterone, increases in liver enzymes and greater suppression of HIV RNA. The reports of lipodystrophy in a small percentage of antiretroviral-naive patients suggests that factors other than antiretroviral therapy may be involved in the aetiology of this syndrome or that some conditions, such as wasting or age-associated obesity, may mimic lipoatrophy and lipohypertrophy, respectively.

Epidemiology of hepatitis C virus infection among injecting drug users in Australia

STUDY OBJECTIVE

To review the epidemiology of hepatitis C virus (HCV) infection among injecting drug users (IDUs) in Australia, and consider needs for further research and prevention policies and programmes.

DESIGN

(1) Review of the results of surveillance for HCV; (2) review of published literature on prevalence, incidence, and risk factors for HCV among IDUs; and (3) reconstruction of incidence rates from prevalence studies of HCV in IDUs.

SETTING AND PARTICIPANTS

Field and clinic based studies of IDUs in Australia.

MAIN RESULTS

HCV has been present at high prevalences (of the order of 60-70%) in populations of Australian IDUs since at least 1971. Duration of injecting and main drug injected were the main predictors of seropositivity, the latter possibly a surrogate for frequency of injecting and both together as surrogate for cumulative numbers of times injected. Risk of infection begins with first injection and continues as long as injecting does. Current incidence is approximately 15 per 100 person years, and up to 40 per 100 person years in some subpopulations. Incidence may have decreased through the 1980s as a result of behaviour change in relation to HIV, as it has for hepatitis B, but not significantly so.

CONCLUSIONS

Control of HCV infection in Australia will depend on effectiveness of measures to control HCV spread among IDUs. This will be a greater challenge than the control of HIV in this population has been. Needs identified include improved surveillance, especially for recently acquired infection, better understanding of exact transmission modes, and urgent improvement in prevention strategies.

Cultures of sexual adventurism as markers of HIV seroconversion: a case control study in a cohort of Sydney gay men

A case control analysis within an ongoing cohort study was used to examine differences between seroconverters and men who remained HIV-negative. The cases were interviewed within one to 13 months prior to their seroconversion. Their responses to a structured questionnaire were compared with those of HIV-negative controls drawn from the same time period and from the same longitudinal study, Sydney Men and Sexual Health. Data collected from both cases and controls included: demographic and contextual variables, knowledge of HIV transmission, sexual practices, drug and alcohol use and attitudinal factors. The aim was to compare the sexual behaviours, and the social and cultural contexts of such behaviours, of men prior to their HIV seroconversion with men who did not seroconvert. Twenty-three men had seroconverted within the cohort. Cases were identified by a positive HIV antibody test or self-report of positive HIV status following a previous negative HIV test. Three-hundred-and-sixty-nine controls were selected on the basis of being HIV negative at interview in 1994, and having at least one subsequent medically-confirmed negative HIV antibody test. Univariate predictors of seroconversion were: being in a regular relationship with a known HIV-positive partner, drug use, and engaging in a range of anal and esoteric sexual practices. Practices commonly used to enhance sexual pleasure, such as group sex, watching and being watched having sex, the use of sex toys and dressing up/fantasy, were engaged in more frequently by seroconverters. Engaging in these esoteric sexual practices was highly correlated with drug use, involvement in the gay community and engagement in a wide range of anal practices. In the multivariate analysis independent predictors of seroconversion were: younger age; being in a regular relationship with a known HIV-positive partner; believing withdrawal to be safe with regard to HIV transmission; and range of esoteric practices. These results indicate the importance of the social and cultural contexts of particular sexual practices and consequent HIV transmission. Sexually adventurous men may be at increased risk for HIV because they seek sex within particular sexual sub-cultures.

Characterization of three nef-defective human immunodeficiency virus type 1 strains associated with long-term nonprogression. Australian Long-Term Nonprogressor Study Group

Long-term survivors (LTS) of human immunodeficiency virus type 1 (HIV-1) infection provide an opportunity to investigate both viral and host factors that influence the rate of disease progression. We have identified three HIV-1-infected individuals in Australia who have been infected for over 11 years with viruses that contain deletions in the nef and nef-long terminal repeat (nef/LTR) overlap regions. These viruses differ from each other and from other nef-defective strains of HIV-1 previously identified in Australia. One individual, LTS 3, is infected with a virus containing a nef gene with a deletion of 29 bp from the nef/LTR overlap region, resulting in a truncated Nef open reading frame. In addition to the Nef defect, only viruses containing truncated Vif open reading frames of 37 or 69 amino acids could be detected in peripheral blood mononuclear cells isolated from this patient. LTS 3 had a viral load of less than 20 copies of RNA/ml of plasma. The other two long-term survivors, LTS 9 and LTS 11, had loads of less than 200 copies of RNA/ml of plasma and are infected with viruses with larger deletions in both the nef alone and nef/LTR overlap regions. These viruses contain wild-type vif, vpu, and vpr accessory genes. All three strains of virus had envelope sequences characteristic of macrophagetropic viruses. These findings further indicate the reduced pathogenic potential of nef-defective viruses.

The 15-Country Collaborative Study of Cancer Risk Among Radiation Workers in the Nuclear Industry: design, epidemiological methods and descriptive results

Radiation protection standards are based mainly on risk estimates from studies of atomic bomb survivors in Japan. The validity of extrapolations from the relatively high-dose acute exposures in this population to the low-dose, protracted or fractionated environmental and occupational exposures of primary public health concern has long been the subject of controversy. A collaborative retrospective cohort study was conducted to provide direct estimates of cancer risk after low-dose protracted exposures. The study included nearly 600,000 workers employed in 154 facilities in 15 countries. This paper describes the design, methods and results of descriptive analyses of the study. The main analyses included 407,391 nuclear industry workers employed for at least 1 year in a participating facility who were monitored individually for external radiation exposure and whose doses resulted predominantly from exposure to higher-energy photon radiation. The total duration of follow-up was 5,192,710 person-years. There were 24,158 deaths from all causes, including 6,734 deaths from cancer. The total collective dose was 7,892 Sv. The overall average cumulative recorded dose was 19.4 mSv. A strong healthy worker effect was observed in most countries. This study provides the largest body of direct evidence to date on the effects of low-dose protracted exposures to external photon radiation.

Characteristics and treatment outcomes among HIV-infected individuals in the Australian Trial in Acute Hepatitis C

BACKGROUND

The Australian Trial in Acute Hepatitis C (ATAHC) is a National Institutes of Health-funded prospective cohort study of the natural history and efficacy of treatment in individuals with recently acquired hepatitis C. Enrollment is open to both human immunodeficiency virus (HIV)-infected and -uninfected individuals. The aim of this article was to evaluate characteristics and virological outcomes among HIV-infected individuals enrolled in ATAHC.

METHODS

Eligibility criteria included the first positive result of testing for anti-hepatitis C virus (HCV) antibody within 6 months and either clinical hepatitis diagnosed within the past 12 months or documented anti-HCV seroconversion within the past 24 months.

RESULTS

Of the initial 103 patients enrolled, 27 (26%) were HIV infected. HIV-infected patients were more likely to be older, to have HCV genotype 1 infection and high levels of HCV RNA at baseline than were HCV-monoinfected patients. Sexual acquisition accounted for the majority (56%) of HCV infections among HIV-infected patients, compared with only 8% of HCV-monoinfected patients. The median duration from estimated HCV infection to treatment was 30 weeks. Treatment with 24 weeks of pegylated interferon and ribavirin resulted in rates of undetectability of HCV RNA of 95%, 90%, and 80% at weeks 12, 24, and 48, respectively. Undetectability at week 4 was achieved in 44% of patients and yielded positive and negative predictive values for sustained virological response of 100% and 33%, respectively.

CONCLUSIONS

Significant differences were demonstrated between HIV-infected and HIV-uninfected individuals enrolled in ATAHC. Treatment responses among HIV-infected individuals with both acute and early chronic infection are encouraging and support regular HCV screening of high-risk individuals and early treatment for recently acquired HCV infection.

Response of experimental animals to human carcinogens: an analysis based upon the IARC Monographs programme

Only the results of epidemiological studies can be used to establish a causal relationship between an exposure to an agent and human cancer; however, such studies often cannot be carried out due to limitations of population or latent period or to the presence of mixed exposures. It is essential, therefore, that the validity be established of extrapolating to humans the results obtained from long-term carcinogenicity tests in animals. The responses of experimental animals to known and suspected human carcinogens, as evaluated in the IARC Monographs series, were analysed as an indication of the sensitivity of animal tests for predicting human carcinogens. Although the response was high - 84% - it would have been even higher had all the compounds been adequately tested experimentally. An additional finding was that for many exposures causally related to human cancer, there is a target organ in common between humans and at least one animal species, despite many inherent physiological differences. These findings show clearly the importance of experimental carcinogenicity studies in the primary prevention of cancer.

Predictive markers of AIDS dementia complex: CD4 cell count and cerebrospinal fluid concentrations of beta 2-microglobulin and neopterin

A predictive marker for AIDS dementia complex (ADC) in a cohort of neurologically asymptomatic human immunodeficiency virus type 1 (HIV-1)-infected patients with < 200 CD4 cells/microL was sought. Patients were assessed neurologically and neuropsychologically at entry. Blood and cerebrospinal fluid (CSF) were taken for assay of beta 2-microglobulin (beta 2M), and neopterin and T cell subsets were assessed from blood. Patients were evaluated every 4 months. Of 37 patients recruited, 35 had sufficient follow-up data. Seventeen patients progressed to ADC stage > or = 1. In univariate analyses, concentrations of CSF beta 2M and neopterin and CD4 cell count were each significantly associated with ADC development. In a multivariate analysis, concentrations of CSF beta 2M remained significant, with levels > 5 mg/L carrying approximately 17 times the risk of ADC. CSF beta 2M and neopterin levels and CD4 cell count are useful in identifying patients at risk of ADC and as such can be used to target high-risk patients so therapy can be optimized.

Colon cancer in Argentina. I: Risk from intake of dietary items

A case-control study has been conducted to investigate the relationship between dietary components and risk of colon cancer in the La Plata area of Argentina. Cases are 110 patients newly diagnosed with colon cancer in 10 major hospitals between 1985 and 1986. Two neighbourhood controls per case were individually matched by age, sex and place of residence. Personal interviews elicited information on frequency of consumption of 140 food items during the 5-year period up to 6 months prior to interview. Risk is analyzed by quartiles of individual food items and groups of items. Multivariate conditional logistic regression modelling indicates that consumption of eggs is associated with increased risk for colon cancer (odds ratios by quartile: 1.0, 1.58, 2.02, 4.66), as are some dairy products (ORs of 1.93 for the highest quartile of consumption of cheese). Intake of vegetables, fish and poultry is associated with statistically significant decreasing risk (ORs of 0.075, 0.39 and 0.39, for the highest categories of consumption of vegetables, fish and poultry, respectively). The risk for red meat does not consistently increase as consumption increases. Risks are not altered by the inclusion of potential confounders such as education or body mass index. These findings confirm those of several previous studies and are of particular interest, since the Argentinean diet typically includes a high intake of red meat.

Non-melanoma skin cancer: ten years of cancer-registry-based surveillance

The Tasmanian Cancer Registry carried out population-based surveillance of non-melanoma skin cancer (NMSC) from 1978 to 1987. A total of 8,651 NMSC were recorded in 7,160 individuals, representing an age-standardized rate of 161/100,000 per year. Ninety-four percent of cases were based on histological diagnosis. Incidence of basal-cell carcinoma (BCC) was higher than the incidence of squamous-cell carcinoma (SCC). The incidence of NMSC was twice as high in men as in women. Incidence increased substantially with age, more markedly for SCC than BCC. For most body sites, BCC was more frequent, but on highly exposed sites such as the backs of hands, lower limbs in women and ears in men, the incidence of SCC was higher. There was an overall increase of 7% per year in the age-standardized incidence rate of NMSC. The increase was more marked for BCC than for SCC, and was consistent across age groups and both sexes. A first NMSC during the study period was associated with a 12-fold increase among men and a 15-fold increase among women in the risk of development of a new NMSC within 5 years, when compared with the NMSC incidence recorded for the population as a whole.

Occupational exposure to pesticides and risk of non-Hodgkin's lymphoma

Pesticide exposure may be a risk factor for non-Hodgkin's lymphoma, but it is not certain which types of pesticides are involved. A population-based case-control study was undertaken in 2000-2001 using detailed methods of assessing occupational pesticide exposure. Cases with incident non-Hodgkin's lymphoma in two Australian states (n = 694) and controls (n = 694) were chosen from Australian electoral rolls. Logistic regression was used to estimate the risks of non-Hodgkin's lymphoma associated with exposure to subgroups of pesticides after adjustment for age, sex, ethnic origin, and residence. Approximately 10% of cases and controls had incurred pesticide exposure. Substantial exposure to any pesticide was associated with a trebling of the risk of non-Hodgkin's lymphoma (odds ratio = 3.09, 95% confidence interval: 1.42, 6.70). Subjects with substantial exposure to organochlorines, organophosphates, and "other pesticides" (all other pesticides excluding herbicides) and herbicides other than phenoxy herbicides had similarly increased risks, although the increase was statistically significant only for "other pesticides." None of the exposure metrics (probability, level, frequency, duration, or years of exposure) were associated with non-Hodgkin's lymphoma. Analyses of the major World Health Organization subtypes of non-Hodgkin's lymphoma suggested a stronger effect for follicular lymphoma. These increases in risk of non-Hodgkin's lymphoma with substantial occupational pesticide exposure are consistent with previous work.

Does the frequency of HIV and STI testing among men who have sex with men in primary care adhere with Australian guidelines?

OBJECTIVES

Australian guidelines recommend annual testing for HIV and sexually transmitted infections (STIs) for all men who have sex with men (MSM) and 3-6 monthly testing for those at higher risk as defined by behavioural criteria. We assessed HIV/STI re-testing rates among MSM attending primary care clinics.

METHODS

We conducted a retrospective follow-up of HIV negative MSM tested for HIV or STIs (chlamydia or syphilis) at four primary care clinics in the 9-month period: April to December 2006. Re-testing rates for these infections were calculated over 18 months. Logistic regression was undertaken to identify predictors of guideline adherence.

RESULTS

Of the MSM requiring annual HIV testing according to the guidelines, the re-testing rates at 1 y were 35% (762/2163). Among the higher risk MSM, 6-monthly HIV re-testing rates were 15% (283/1862). Within the subgroup who reported 11 or more male sexual partners within the past 6 months, HIV re-testing rates within 6 months were 19%. Independent predictors of HIV re-testing within 6 months in higher-risk MSM were reporting 11 or more male sexual partners in the last 6 months (AOR 3.1, 95% CI 1.8 to 4.8); being born overseas (AOR 2.0, 95% CI 1.2 to 3.4); and previous HIV testing more than 12 months earlier (AOR 3.3, 95% CI 1.9 to 5.5).

CONCLUSION

There is poor adherence to national guidelines that recommend regular re-testing of MSM for STIs, particularly among those at higher risk who require more frequent testing. Clinical strategies are urgently needed to encourage more frequent HIV/STI testing among MSM, especially in the higher risk subgroup.