Cancer mortality in a cohort of male agricultural workers from northern Italy

A cohort study of banana plantation workers in the French West Indies: first mortality analysis (2000-2015)

Chlordecone, an organochlorine insecticide, was widely used in the French West Indies banana plantations. We set up a cohort of banana plantation workers who worked between 1973 and 1993, the period of authorized use of chlordecone. Vital status and causes of death were collected from French national registries. Workers were followed up from 1 January 2000 to 31 December 2015. Cause-specific mortality in the cohort was compared to that of the general population of the French West Indies by computing standardized mortality ratios (SMRs). A total of 11,112 workers (149,526 person-years, 77% men) were included in the mortality analysis, and 3647 deaths occurred over the study period. There was a slight deficit in all-cause mortality, which was statistically significant in men (SMR = 0.93, 95% CI 0.89-0.96), but not in women (SMR = 0.96, 95% CI 0.89-1.04). All-cancer mortality did not differ significantly from that of the general population (men: SMR = 0.96, 95% CI 0.90-1.03; women: SMR = 1.04, 95% CI 0.89-1.21). Significant excesses of deaths were observed for stomach cancer in women (SMR = 1.94, 95% CI 1.24-2.89) and pancreatic cancer in women farm owners (SMR = 2.31, 95% CI 1.06-4.39). Mortality from prostate cancer was similar to that of the general population in the whole cohort (SMR = 1.00; 95% CI 0.89-1.13) and non-significantly elevated among farm workers (SMR = 1.10, 95% CI 0.87-1.36). Non-significant increases in mortality were also observed for lung cancer in women, leukemia in men, and non-Hodgkin lymphoma in both genders.

Occupational Risk Factors for Prostate Cancer: A Meta-analysis

Prostate cancer is the second most common cancer in men worldwide. There are many occupational factors that have been suggested to cause prostate cancer. Our aim was to evaluate the evidence for causality by a literature review of occupational factors. We searched literature in Medline and SCOPUS from 1966 to June 30, 2015 to identify occupational risk factors for prostate cancer. The following risk factors were selected: farmers/agricultural workers, pesticides - whole group, and separately organophosphate and organochlorine pesticides, carbamates and triazines, cadmium, chromium, cutting fluids, acrylonitrile, rubber manufacturing, whole body vibration, shift work, flight personnel, ionizing radiation, and occupational physical activity. For each factor a literature search was performed and presented as meta-analysis of relative risk and heterogeneity (Q and I2 index). A total of 168 original studies met the inclusion criteria with 90,688 prostate cancer cases. Significantly increased risks were observed for the following occupational exposures: pesticides (metaRR = 1.15, 95% confidence interval [CI] = 1.01-1.32; I2 = 84%), and specifically group of organochlorine pesticides (meta relative risk [metaRR] = 1.08, 95% CI = 1.03-1.14; I2 = 0%), chromium (metaRR = 1.19, 95% CI = 1.07-1.34; I2 = 31%), shift work (metaRR = 1.25, 95% CI = 1.05-1.49; I2 = 78%) and pilots (metaRR = 1.41, 95% CI = 1.02-1.94; I2 = 63%) and occupational physical activity in cohort studies (metaRR = 0.87, 95% CI = 0.81-0.94; I2 = 0%). The literature review supports a causal association for a few of the previously suggested factors.

Cancer incidence in the AGRICAN cohort study (2005-2011)

BACKGROUND

Numerous studies have been conducted among farmers, but very few of them have involved large prospective cohorts, and few have included a significant proportion of women and farm workers. Our aim was to compare cancer incidence in the cohort (overall, by sex, and by work on farm, occupational status and pesticide use) within the general population.

METHODS

More than 180,000 participants in the AGRICAN cohort were matched to cancer registries to identify cancer cases diagnosed from enrolment (2005-2007) to 31st December 2011. We calculated standardized incidence ratios (SIRs) and 95% confidence intervals (95%CIs).

RESULTS

Over the period, 11,067 incident cancer cases were identified (7304 men and 3763 women). Overall cancer incidence did not differ between the cohort and the general population. Moreover, SIRs were significantly higher for prostate cancer (SIR=1.07, 95%CI 1.03-1.11) and non-Hodgkin lymphoma (SIR=1.09, 95%CI 1.01-1.18) among men, skin melanoma among women (SIR=1.23, 95%CI 1.05-1.43) and multiple myeloma (men: SIR=1.38, 95%CI 1.18-1.62; women: SIR=1.26, 95%CI 1.02-1.54). In contrast, SIRs were lower for upper aerodigestive tract and respiratory cancers. Increase in risk was greater in male farm workers for prostate and lip cancer, in female farm workers for skin melanoma, and in male farm owners for multiple myeloma. Moreover, incidence of multiple myeloma and skin melanoma was higher among male and female pesticide users respectively.

CONCLUSION

We found a decreased incidence for tobacco-related cancers and an increased incidence of prostate cancers, skin melanoma and multiple myeloma. Specific subgroups had a higher cancer incidence related to occupational status and pesticide use.

Prognostic Factors for Survival in Patients with Gastric Cancer using a Random Survival Forest

Background:

Gastric cancer is the fifth most common cancer and the third top cause of cancer related death with about 1 million new cases and 700,000 deaths in 2012. The aim of this investigation was to identify important factors for outcome using a random survival forest (RSF) approach.

Materials and Methods:

Data were collected from 128 gastric cancer patients through a historical cohort study in Hamedan-Iran from 2007 to 2013. The event under consideration was death due to gastric cancer. The random survival forest model in R software was applied to determine the key factors affecting survival. Four split criteria were used to determine importance of the variables in the model including log-rank, conversation?? of events, log-rank score, and randomization. Efficiency of the model was confirmed in terms of Harrell’s concordance index.

Results:

The mean age of diagnosis was 63 ±12.57 and mean and median survival times were 15.2 (95%CI: 13.3, 17.0) and 12.3 (95%CI: 11.0, 13.4) months, respectively. The one-year, two-year, and three-year rates for survival were 51%, 13%, and 5%, respectively. Each RSF approach showed a slightly different ranking order. Very important covariates in nearly all the 4 RSF approaches were metastatic status, age at diagnosis and tumor size. The performance of each RSF approach was in the range of 0.29-0.32 and the best error rate was obtained by the log-rank splitting rule; second, third, and fourth ranks were log-rank score, conservation of events, and the random splitting rule, respectively.

Conclusion:

Low survival rate of gastric cancer patients is an indication of absence of a screening program for early diagnosis of the disease. Timely diagnosis in early phases increases survival and decreases mortality.

Gastric cancer incidence in the Romagna Region of Italy: A spatial and temporal analysis

BACKGROUND

The worldwide decrease in gastric cancer incidence is due to a birth-cohort-dependent decrease in exposure to major risk factors.

METHODS

In an area of northern Italy with a historically strong internal geographical gradient in gastric cancer incidence, variations in rates by municipality and age group between 1987 and 2008 were evaluated. The study period was divided into three nonadjacent periods. End points included: age- and sex-standardised incidence rates; incidence rate ratio between age- and sex-standardised incidence rates; smoothed relative risks of gastric cancer incidence, and posterior probabilities of the relative risk being >1.

RESULTS

In 1987-1990, the estimate of posterior probabilities of relative risk being >1 showed a higher incidence in hilly/mountainous areas. Between 1987-1990 and 2005-2008, a uniform decrease of more than 50% was observed (incidence rate ratio: plain, 0.45 (95% confidence interval 0.40-0.51); hill, 0.44 (0.34-0.58); mountain, 0.48 (0.22-1.02)). The decrease in the mountainous area was weak in the middle time period, with an incidence rate ratio of 0.92 (0.46-1.84), and intensified afterwards. The decrease occurred earlier and was more pronounced among younger people. In 2005-2008, gastric cancer risk was uniform across ages and municipalities.

CONCLUSIONS

The observed changes in gastric cancer incidence is the epilogue of a birth-cohort-dependent decrease in exposure to major risk factors.

A review of prostate cancer incidence and mortality studies of farmers and non-farmers, 2002-2013

OBJECTIVES

To review the recent literature on the incidence and mortality of prostate cancer in farmers compared to non-farmers.

METHODS

Searches were conducted in seven electronic databases for observational studies published from 2002 to 2013. Studies were assessed against eligibility criteria and a narrative summary of findings presented.

RESULTS

Eighteen primary research articles were included in the review. Four of ten mortality studies and two of nine incidence studies reported statistically significant increases in prostate cancer risk in farmers. However, nearly half of all studies reported non-significant reductions in farmers' risk. Additionally, one study reported significantly increased and decreased risk using different outcome measures. Results varied considerably by geographic region, study design and degree of control for confounders, affecting comparability and strength of findings.

CONCLUSIONS

The overall evidence for increased prostate cancer risk in farmers was weak.

The epidemiology of glioma in adults: a "state of the science" review

Gliomas are the most common primary intracranial tumor, representing 81% of malignant brain tumors. Although relatively rare, they cause significant mortality and morbidity. Glioblastoma, the most common glioma histology (∼45% of all gliomas), has a 5-year relative survival of ∼5%. A small portion of these tumors are caused by Mendelian disorders, including neurofibromatosis, tuberous sclerosis, and Li-Fraumeni syndrome. Genomic analyses of glioma have also produced new evidence about risk and prognosis. Recently discovered biomarkers that indicate improved survival include O⁶-methylguanine-DNA methyltransferase methylation, isocitrate dehydrogenase mutation, and a glioma cytosine-phosphate-guanine island methylator phenotype. Genome-wide association studies have identified heritable risk alleles within 7 genes that are associated with increased risk of glioma. Many risk factors have been examined as potential contributors to glioma risk. Most significantly, these include an increase in risk by exposure to ionizing radiation and a decrease in risk by history of allergies or atopic disease(s). The potential influence of occupational exposures and cellular phones has also been examined, with inconclusive results. We provide a “state of the science” review of current research into causes and risk factors for gliomas in adults.

Application of smoothing methods for determining of the effecting factors on the survival rate of gastric cancer patients

Background

Smoothing methods are widely used to analyze epidemiologic data, particularly in the area of environmental health where non-linear relationships are not uncommon. This study focused on three different smoothing methods in Cox models: penalized splines, restricted cubic splines and fractional polynomials.

Objectives

The aim of this study was to assess the effects of prognostic factors on survival of patients with gastric cancer using the smoothing methods in Cox model and Cox proportional hazards. Also, all models were compared to each other in order to find the best one.

Materials and Methods

We retrospectively studied 216 patients with gastric cancer who were registered in one referral cancer registry center in Tehran, Iran. Age at diagnosis, sex, presence of metastasis, tumor size, histology type, lymph node metastasis, and pathologic stages were entered in to analysis using the Cox proportional hazards model and smoothing methods in Cox model. The SPSS version 18.0 and R version 2.14.1 were used for data analysis. These models compared with Akaike information criterion.

Results

In this study, The 5 year survival rate was 30%. The Cox proportional hazards, penalized spline and fractional polynomial models let to similar results and Akaike information criterion showed a better performance for these three models comparing to the restricted cubic spline. Also, P-value and likelihood ratio test in restricted cubic spline was greater than other models. Note that the best model is indicated by the lowest Akaike information criterion.

Conclusions

The use of smoothing methods helps us to eliminate non-linear effects but it is more appropriate to use Cox proportional hazards model in medical data because of its’ ease of interpretation and capability of modeling both continuous and discrete covariates. Also, Cox proportional hazards model and smoothing methods analysis identified that age at diagnosis and tumor size were independent prognostic factors for the survival of patients with gastric cancer (P < 0.05). According to these results the early detection of patients at younger age and in primary stages may be important to increase survival.

Estimation of hazard function and its associated factors in gastric cancer patients using wavelet and kernel smoothing methods

BACKGROUND AND OBJECTIVES

Increase of mortality rates of gastric cancer in Iran and the world in recent years reveal necessity of studies on this disease. Here, hazard function for gastric cancer patients was estimated using Wavelet and Kernel methods and some related factors were assessed.

MATERIALS AND METHODS

Ninety- five gastric cancer patients in Fayazbakhsh Hospital between 1996 and 2003 were studied. The effects of age of patients, gender, stage of disease and treatment method on patient's lifetime were assessed. For data analyses, survival analyses using Wavelet method and Log-rank test in R software were used.

RESULTS

Nearly 25.3% of patients were female. Fourteen percent had surgery treatment and the rest had treatment without surgery. Three fourths died and the rest were censored. Almost 9.5% of patients were in early stages of the disease, 53.7% in locally advance stage and 36.8% in metastatic stage. Hazard function estimation with the wavelet method showed significant difference for stages of disease (P<0.001) and did not reveal any significant difference for age, gender and treatment method.

CONCLUSION

Only stage of disease had effects on hazard and most patients were diagnosed in late stages of disease, which is possibly one of the most reasons for high hazard rate and low survival. Therefore, it seems to be necessary a public education about symptoms of disease by media and regular tests and screening for early diagnosis.

The Upper Midwest Health Study: a case-control study of pesticide applicators and risk of glioma

BACKGROUND

An excess incidence of brain cancer in farmers has been noted in several studies. The National Institute for Occupational Safety and Health developed the Upper Midwest Health Study (UMHS) as a case-control study of intracranial gliomas and pesticide uses among rural residents. Previous studies of UMHS participants, using "ever-never" exposure to farm pesticides and analyzing men and women separately, found no positive association of farm pesticide exposure and glioma risks. The primary objective was to determine if quantitatively estimated exposure of pesticide applicators was associated with an increased risk of glioma in male and female participants.

METHODS

The study included 798 histologically confirmed primary intracranial glioma cases (45 % with proxy respondents) and 1,175 population-based controls, all adult (age 18-80) non-metropolitan residents of Iowa, Michigan, Minnesota, and Wisconsin. The analyses used quantitatively estimated exposure from questionnaire responses evaluated by an experienced industrial hygienist with 25 years of work on farm pesticide analyses. Odds ratios (ORs) and 95 % confidence intervals (CIs) using unconditional logistic regression modeling were calculated adjusting for frequency-matching variables (10-year age group and sex), and for age and education (a surrogate for socioeconomic status). Analyses were separately conducted with or without proxy respondents.

RESULTS

No significant positive associations with glioma were observed with cumulative years or estimated lifetime cumulative exposure of farm pesticide use. There was, a significant inverse association for phenoxy pesticide used on the farm (OR 0.96 per 10 g-years of cumulative exposure, CI 0.93-0.99). No significant findings were observed when proxy respondents were excluded. Non-farm occupational applicators of any pesticide had decreased glioma risk: OR 0.72, CI 0.52-0.99. Similarly, house and garden pesticide applicators had a decreased risk of glioma: OR 0.79, CI 0.66-0.93, with statistically significant inverse associations for use of 2,4-D, arsenates, organophosphates, and phenoxys.

CONCLUSIONS

These results are consistent with our previous findings for UMHS of reported farm pesticide exposure and support a lack of positive association between pesticides and glioma.

Prevalence and changes in chronic diseases among South Korean farmers: 1998 to 2005

Background

Epidemiologic studies have suggested a unique pattern of disease among farmers in Western countries, but limited information is available about the magnitude of disease prevalence and their changes over time in Asian farmers. The aim of this study was to compare the prevalence and changes in chronic diseases among farmers with those of other occupational groups in South Korea.

Methods

Using data from three consecutive cross-sectional national surveys: the Korean National Health and Nutrition Examination Survey 1998 (n = 39,060), 2001 (n = 37,769), and 2005 (n = 34,145), we calculated age and gender-standardized prevalence of chronic diseases by the direct method and compared the prevalence changes from 1998 to 2005.

Results

Female farmers had significantly higher chronic disease prevalence than other occupational groups in all three surveys. Arthritis was the most prevalent chronic disease among farmers for both men and women. Compared with other populations, farmers demonstrated a higher prevalence of arthritis and intervertebral disc disorders. Farmers showed higher prevalence changes for intervertebral disc disorders than other occupational workers.

Conclusion

Our findings support that South Korean farmers have a distinct pattern of diseases prevalence from other populations. More detailed studies investigating the risk of musculoskeletal diseases and intensive intervention efforts to reduce the prevalence these diseases, particularly among female farmers, are required.

Exposure to farm crops, livestock, and farm tasks and risk of glioma: the Upper Midwest Health Study

Some studies of brain cancer have found an excess risk for farmers. The National Institute for Occupational Safety and Health previously found no increased glioma risk for ever (vs. never) being exposed to pesticides on a farm among 798 cases and 1,175 population-based controls (adult (ages 18-80 years) nonmetropolitan residents of Iowa, Michigan, Minnesota, and Wisconsin). For this analysis (1995-1998), 288 cases and 474 controls (or their proxies) who had lived on farms at age 18 years or after were asked about exposure to crops, livestock, and farm tasks. Logistic regression was used to calculate odds ratios adjusted for age, age group, sex, state, and education. Never immediately washing up (adjusted odds ratio (OR) = 3.08, 95% confidence interval (CI): 1.78, 5.34) or changing clothes (OR = 2.84, 95% CI: 1.04, 7.78) after applying pesticides was associated with increased glioma risk. Living on a farm on which corn, oats, soybeans, or hogs were raised was associated with decreased risk (corn-OR = 0.37, 95% CI: 0.20, 0.69; oats-OR = 0.63, 95% CI: 0.40, 1.00; soybeans-OR = 0.69, 95% CI: 0.48, 0.98; hogs-OR = 0.63, 95% CI: 0.43, 0.93). Negative associations may be due to chance or a "healthy farmer" effect. Farmers' increased risk of glioma may be due to work practices, other activities, or an inverse association with allergies (reported by other investigators).

Agricultural exposures and gastric cancer risk in Hispanic farm workers in California

Previous studies have indicated that farm workers may be at increased risk of gastric cancer. Meta-analyses, ecological, case-control, and cohort studies suggest that some aspects of the agricultural environment may be implicated in the elevated risk. Hispanic farm workers in California are exposed to a multitude of potentially toxic substances in the work site, including excessive sunlight, fertilizers, diesel fumes, and pesticides. A previous analysis of a cohort of California farm workers who had been members of a farm labor union, the United Farm Workers of America (UFW) found a proportionate cancer incidence ratio for stomach cancer of 1.69 when using the California Hispanic population as the standard. The aim of the current study was to further evaluate associations between gastric cancer and the types of crops and commodities UFW members cultivate and the associated pesticide use as recorded by the California Department of Pesticide Regulation (DPR). We conducted a nested case-control study of gastric cancer embedded in the UFW cohort and identified 100 cases of newly diagnosed gastric cancer between 1988 and 2003. We identified 210 control participants matched on age, gender, ethnicity, and who were known to be alive and resident in California up to the date of the cases' diagnosis. Both stratified analyses and unconditional logistic regression were used to calculate adjusted odds ratios (OR) and 95% confidence intervals (95% CI). Work in the citrus industry was associated with increased gastric cancer (OR=2.88; 95% CI=1.02-8.12) although no other specific crops or commodities were associated with this disease. Working in areas with high use of the phenoxyacetic acid herbicide 2,4-D was associated with gastric cancer (OR=1.85; 95% CI=1.05-3.25); use of the organochlorine insecticide chlordane was also associated with the disease (OR=2.96; 95% CI=1.48-5.94). Gastric cancer was associated with use of the acaricide propargite and the herbicide triflurin (OR=2.86; 95% CI=1.56-5.23 and 1.69, 95% CI=0.99-2.89, respectively). Gastric cancer in California Hispanic farm workers is associated with work in the citrus fruit industry and among those who work in fields treated with 2,4-D, chlordane, propargite, and trifluin. These findings may have larger public health implications especially in those areas of the country where these pesticides are heavily used and where they may be found in the ambient atmosphere.

A systematic review of myeloid leukemias and occupational pesticide exposure

OBJECTIVE

To conduct a systematic review and meta-analyses of published studies examining the association between myeloid leukemias (ML) and occupational pesticide exposure.

METHODS

Studies were identified from a MEDLINE search through 31 May 2006 and from the reference lists of identified publications. Studies were summarized and evaluated for publication bias. Relative risk estimates for ML were extracted from 17 cohort and 16 case-control studies published between 1979 and 2005. Fixed- or random-effect meta-analysis models were used depending on the presence of heterogeneity between studies. Separate analyses were conducted after stratification for study design, occupational group, ML subtype or gender.

RESULTS

The overall meta-rate ratio estimate (meta-RR) for the cohort studies was 1.21 (95% confidence interval [CI] 0.99-1.48). Substantial heterogeneity existed among cohort studies (p=1.064 x 10(-5)), mainly reflecting the varying occupational categories examined. The meta-RR was 6.32 (95% CI: 1.90-21.01) for manufacturing workers and 2.14 (95% CI: 1.39-3.31) for pesticide applicators. After stratification of cohort studies by specific ML subtype, an increased risk of acute myeloid leukemia (AML) was found (meta-RR: 1.55; 95% CI: 1.02-2.34). No significant heterogeneity was detected among case-control studies and an increased risk of chronic myeloid leukemia (CML) was found among men (meta-RR: 1.39; 95% CI: 1.03-1.88) and farmers or agricultural workers (meta-RR: 1.38; 95% CI: 1.06-1.79).

CONCLUSION

The strongest evidence of an increased risk of ML comes from manufacturing workers and pesticide applicators. Further studies will be needed to correlate reliable exposure data within these specific occupational groups with well-defined subtypes of leukemia to refine this assessment.

Relative and absolute cancer mortality of women in agriculture in northern Italy

Most studies of cancer risk related to agricultural exposures have focused on male operators. Cancer mortality in a cohort of 38 962 women engaged in agriculture (Province of Forlì, 1969-1993) was compared with that of the rest of the female residents using the ratio of age-standardized (Europe) mortality rates (ASR) with 95% confidence interval (CI). Moreover, mortality time trends in both subsets of the population were evaluated. The cohort yielded 798 439 person-years with 2397 cancer deaths. Total ASR ratio was 0.86 (95% CI 0.80-0.92). Only gastric cancer was associated with a significant but declining excess mortality (ASR ratio 1.26; 95% CI 1.11-1.43). Total ASR ratio decreased from 1.07 (95% CI 0.95-1.20) in 1969-1976 to 0.74 (95% CI 0.66-0.82) in 1985-1993. This resulted from a downward mortality trend restricted to the cohort. In particular, mortality from cancers of the oesophagus, stomach and colon/rectum decreased more steeply in the cohort. Mortality from liver cancer decreased only in the cohort. Mortality from cancers of the pancreas, lung, breast, bladder and skin melanoma remained stable in the cohort whilst increasing in the rest of the population. In conclusion, risk excesses previously reported were not confirmed. Agricultural workers qualified as a subset of the female population with atypical, favourable epidemiologic characteristics.

Gliomas and Farm Pesticide Exposure in Men: The Upper Midwest Health Study

The National Institute for Occupational Safety and Health evaluated farm pesticide exposure and glioma risk in a study that included 457 glioma cases and 648 population-based controls, all adult men (18-80 yr old) and nonmetropolitan residents of Iowa, Michigan, Minnesota, and Wisconsin. Multiple logistic regressions were used to control for farm residence, age, age group, education, and exposure to other pesticides. No associations were found between glioma and 12 specific pesticides. We estimated adjusted odds ratios (ORs) and 95% confidence intervals (CIs) and found reduced glioma risk for insecticides (OR = 0.53, CI = 0.37-0.77), fumigants (OR = 0.57, CI = 0.34-0.95), and organochlorines (OR = 0.66, CI = 0.47-0.94). In analyses excluding proxy respondents (47% of cases) most CIs included 1.0. No positive association of farm pesticide exposure and glioma was found. Other farm exposures may explain the excess brain cancer risk seen in previous studies.