Soft-tissue sarcoma and pesticides exposure in men: results of a Canadian case-control study

Association between occupational exposures and sarcoma incidence and mortality: systematic review and meta-analysis

BACKGROUND

Sarcomas are a rare and heterogeneous group of tumors originating from mesenchymal or connective tissue. They represent less than 1% of all adult cancers. The etiology and epidemiology of sarcomas remain understudied and poorly understood. The main objective of our study was to systematically assess the association between various occupational exposures and risk of sarcomas.

METHODS

We performed a systematic literature search using the PubMed, Scopus, EMBASE and Cochrane databases to identify relevant cohort and case-control studies. A meta-analysis method was applied on the incidence and mortality outcomes where the estimate with 95% confidence interval (CI) was obtained.

RESULTS

We included a total of 50 publications in our systematic review and 35 in meta-analysis. For exposures to phenoxy herbicides and chlorophenols, the pooled odds ratio (OR) for sarcoma was 1.85 (95% CI: 1.22, 2.82), based on 16 studies with 2254 participants, while the pooled standardized mortality ratio was 40.93 (95% CI 2.19, 765.90), based on 4 cohort studies with 59,289 participants. For exposure to vinyl chloride monomers the pooled risk ratios for angiosarcoma of the liver and other STS were 19.23 (95% CI 2.03, 182.46) and 2.23 (95 CI 1.55, 3.22) respectively based on 3 cohort studies with 12,816 participants. Exposure to dioxins was associated with an increased STS mortality; the pooled standardized mortality ratio was 2.56 (95% CI 1.60, 4.10) based on 4 cohort studies with 30,797 participants. Finally, woodworking occupation was associated with an increased risk of STS with the pooled OR of 2.16 (95% CI 1.39, 3.36).

CONCLUSIONS

Our findings suggest a positive association between higher exposure to dioxins and increased mortality from STS, between cumulative exposure to vinyl chloride monomers and increased mortality from angiosarcoma of the liver and STS, and between woodworking occupation and STS incidence. These findings were all statistically significant.

Carcinogenicity and mutagenicity of malathion and its two analogues: a systematic review

Malathion has been widely used worldwide in arbovirus control programs. In 2015, it was classified by the International Agency for Research on Cancer (IARC) as a probable carcinogen to humans. This work aimed to systematize the evidence of the carcinogenic and mutagenic effects associated with the exposure of malathion and its analogs, malaoxon and isomalathion. The search was carried out in Toxline, PubMed and Scopus databases for original papers published from 1983 to 2015. In all, 73 papers were selected from a total of 273 eligible papers. The results of in vitro and in vivo studies showed mainly genetic and chromosomal damages caused by malathion. The epidemiological studies evidenced significant positive associations for thyroid, breast, and ovarian cancers in menopausal women. This evidence of the carcinogenic effect of malathion should be considered before its use in arbovirus control programs.

Pesticide exposure and cancer: an integrative literature review

ABSTRACT We conducted an integrative literature review of published studies on pesticide and cancer exposure, focusing on farmers, rural population, pesticide applicators, and rural workers. The Medline/PubMed was used as searching database. After the retrieval, 74 articles were selected according to pre-established criteria, which design involved 39 case-controls, 32 cohorts, 2 ecological ones, and 1 cross-sectional. Among them, 64 studies showed associations between pesticides and cancer while 10 did not find any significant association. The studies found 53 different types of pesticides significantly associated with at least one type of cancer and 19 different types of cancers linked to at least one type of pesticide. Although few studies presented contradictory results, the sole fact of being a farmer or living near crops or high agricultural areas have also been used as a proxy for pesticide exposure and significantly associated with higher cancer risk. The literature well illustrates the case of prostate cancer, Non-Hodgkin lymphoma, leukemia, multiple myeloma, bladder and colon cancers. Studies are recommended to further investigate the relationship between pesticide and neoplasm of testis, breast, esophagus, kidney, thyroid, lip, head and neck, and bone.

Establishing a role for environmental toxicant exposure induced epigenetic remodeling in malignant transformation

Humans are exposed to a wide variety of environmental exposures throughout their lifespan. These include both naturally occurring toxins and chemical toxicants like pesticides, herbicides, and industrial chemicals, many of which have been implicated as possible contributors to human disease susceptibility [1-3]. We, and others, have hypothesized that environmental exposures may cause adaptive epigenetic changes in regenerative cell populations and developing organisms, leading to abnormal gene expression and increased disease susceptibility later in life [3]. Common epigenetic changes include changes in miRNA expression, covalent histone modifications, and methylation of DNA. Importantly, due to their heritable nature, abnormal epigenetic modifications which occur within stem cells may be particularly deleterious. Abnormal epigenetic changes in regenerative cell linages can be passed onto a large population of daughter cells and can persist for long periods of time. It is well established that an accumulation of epigenetic changes can lead to many human diseases including cancer [4-6]. Subsequently, it is imperative that we increase our understanding of how common environmental toxins and toxicants can induce epigenetic changes, particularly in stem cell populations. In this review, we will discuss how common environmental exposures in the United States and around the world may lead to epigenetic changes and discuss potential links to human disease, including cancer.

Toxicological profile of organochlorines aldrin and dieldrin: an Indian perspective

Several epidemiological studies have suggested various environmental factors as a possible cause for increased incidence of various abnormalities. Of the various environmental contaminants, the most prevalent and the most discussed are the endocrine disrupting chemicals. Contact of such disruptors with humans has become inevitable today. They are cosmopolitan and present from agriculture to industrial sectors, even in day-to-day consumer products. Aldrin and dieldrin belong to one such class of substances which are known to have a toxic effect on various physiological systems of the human body. Despite an imposed ban on their manufacture and commercial use, these pesticides could still be detected in probable areas of consumption like agriculture. The present review discusses the known possible toxic effects of aldrin and dieldrin and their current existence in the ecosystem across India.

Phenoxy herbicides, soft-tissue sarcoma and non-Hodgkin lymphoma: a systematic review of evidence from cohort and case-control studies

BACKGROUND

Phenoxy herbicides have been used widely in agriculture, forestry, parks and domestic gardens. Early studies linked them with soft-tissue sarcoma (STS) and non-Hodgkin lymphoma (NHL), but when last reviewed by the International Agency for Research on Cancer in 1986, the evidence for human carcinogenicity was limited.

SOURCES OF DATA

We searched Medline and Embase, looking for cohort or case-control studies that provided data on risk of STS and/or NHL in relation to phenoxy herbicides, and checked the reference lists of relevant publications for papers that had been missed.

AREAS OF AGREEMENT, AREAS OF CONTROVERSY

The extensive evidence is not entirely consistent, and a hazard of STS or NHL cannot firmly be ruled out. However, if there is a hazard, then absolute risks must be small.

GROWING POINTS, AREAS TIMELY FOR DEVELOPING RESEARCH

Extended follow-up of previously assembled cohorts may be the most efficient way of further reducing uncertainties.

Incidence of solid tumours among pesticide applicators exposed to the organophosphate insecticide diazinon in the Agricultural Health Study: an updated analysis

OBJECTIVE

Diazinon, a common organophosphate insecticide with genotoxic properties, was previously associated with lung cancer in the Agricultural Health Study (AHS) cohort, but few other epidemiological studies have examined diazinon-associated cancer risk. We used updated diazinon exposure and cancer incidence information to evaluate solid tumour risk in the AHS.

METHODS

Male pesticide applicators in Iowa and North Carolina reported lifetime diazinon use at enrolment (1993-1997) and follow-up (1998-2005); cancer incidence was assessed through 2010(North Carolina)/2011(Iowa). Among applicators with usage information sufficient to evaluate exposure-response patterns, we used Poisson regression to estimate adjusted rate ratios (RRs) and 95% CI for cancer sites with ≥10 exposed cases for both lifetime (LT) exposure days and intensity-weighted (IW) lifetime exposure days (accounting for factors impacting exposure).

RESULTS

We observed elevated lung cancer risks (N=283) among applicators with the greatest number of LT (RR=1.60; 95% CI 1.11 to 2.31; P(trend)=0.02) and IW days of diazinon use (RR=1.41; 95% CI 0.98 to 2.04; P(trend)=0.08). Kidney cancer (N=94) risks were non-significantly elevated (RR(LT) days=1.77; 95% CI 0.90 to 3.51; P(trend)=0.09; RR(IW) days 1.37; 95% CI 0.64 to 2.92; P(trend)=0.50), as were risks for aggressive prostate cancer (N=656).

CONCLUSIONS

Our updated evaluation of diazinon provides additional evidence of an association with lung cancer risk. Newly identified links to kidney cancer and associations with aggressive prostate cancer require further evaluation.

Oral contraceptive use, parity, and constitutional characteristics in soft tissue sarcoma: a Swedish population-based case-control study 1988-2009

PURPOSE

The study was designed to investigate the influence of surrogate factors associated with sex (SH) and growth hormones (GH) on the risk of developing soft tissue sarcomas (STS).

BACKGROUND AND METHODS

The etiology of soft tissue sarcoma is largely unknown. We have studied the effect of hormone related factors on STS in the Swedish population between 1988 and 2009 using a population-based matched case-control design.

RESULTS

Our study is the largest on this topic to date, including 634 cases in a primary matched analysis and 855 cases in an unmatched sensitivity analysis. We identified protective effects connected to constitutional characteristics, hormonal and reproductive factors. Being shorter than your peers at age 11 was associated with an odds ratio (OR) of 0.51 (0.36-0.74). Having used oral contraceptives (OC), OR 0.75 (0.49-1.15), and high parity, OR 0.16 (0.04-0.63), comparing three or more children to two or less, also appeared to reduce the risk of STS. The risk was further reduced with the duration of OC use (p = 0.01), comparing use for 11 years or more to use for 3 years or less yielded an OR of 0.10 (0.02-0.41). No effect was observed for ever having had perimenopausal hormone therapy OR 1.02 (0.70-1.47). The effect of BMI varied significantly with subtype (p = 0.03) and tumor location (p < 0.001).

CONCLUSIONS

We observed surrogates of SH, GH, and insulin-like growth factor 1 to be associated with STS development. These findings are important as they may connect STSs to the group of hormone-dependent tumors, potentially revealing common treatment and prevention targets.

Gastrointestinal stromal tumors: a case-only analysis of single nucleotide polymorphisms and somatic mutations

Background

Gastrointestinal stromal tumors are rare soft tissue sarcomas that typically develop from mesenchymal cells with acquired gain-in-function mutations in KIT or PDGFRA oncogenes. These somatic mutations have been well-characterized, but little is known about inherited genetic risk factors. Given evidence that certain susceptibility loci and carcinogens are associated with characteristic mutations in other cancers, we hypothesized that these signature KIT or PDGFRA mutations may be similarly fundamental to understanding gastrointestinal stromal tumor etiology. Therefore, we examined associations between 522 single nucleotide polymorphisms and seven KIT or PDGFRA tumor mutations types. Candidate pathways included dioxin response, toxin metabolism, matrix metalloproteinase production, and immune and inflammatory response.

Methods

We estimated odds ratios and 95% confidence intervals for associations between each candidate SNP and tumor mutation type in 279 individuals from a clinical trial of adjuvant imatinib mesylate. We used sequence kernel association tests to look for pathway-level associations.

Results

One variant, rs1716 on ITGAE, was significantly associated with KIT exon 11 non-codon 557–8 deletions (odds ratio = 2.86, 95% confidence interval: 1.71-4.78) after adjustment for multiple comparisons. Other noteworthy associations included rs3024498 (IL10) and rs1050783 (F13A1) with PDGFRA mutations, rs2071888 (TAPBP) with wild type tumors and several matrix metalloproteinase SNPs with KIT exon 11 codon 557–558 deletions. Several pathways were strongly associated with somatic mutations in PDGFRA, including defense response (p = 0.005) and negative regulation of immune response (p = 0.01).

Conclusions

This exploratory analysis offers novel insights into gastrointestinal stromal tumor etiology and provides a starting point for future studies of genetic and environmental risk factors for the disease.

Review of 2,4-dichlorophenoxyacetic acid (2,4-D) biomonitoring and epidemiology

A qualitative review of the epidemiological literature on the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) and health after 2001 is presented. In order to compare the exposure of the general population, bystanders and occupational groups, their urinary levels were also reviewed. In the general population, 2,4-D exposure is at or near the level of detection (LOD). Among individuals with indirect exposure, i.e. bystanders, the urinary 2,4-D levels were also very low except in individuals with opportunity for direct contact with the herbicide. Occupational exposure, where exposure was highest, was positively correlated with behaviors related to the mixing, loading and applying process and use of personal protection. Information from biomonitoring studies increases our understanding of the validity of the exposure estimates used in epidemiology studies. The 2,4-D epidemiology literature after 2001 is broad and includes studies of cancer, reproductive toxicity, genotoxicity, and neurotoxicity. In general, a few publications have reported statistically significant associations. However, most lack precision and the results are not replicated in other independent studies. In the context of biomonitoring, the epidemiology data give no convincing or consistent evidence for any chronic adverse effect of 2,4-D in humans.