Serum levels of environmental pollutants is a risk factor for breast cancer in Inuit: a case control study

Abstract

BackgroundEnvironmental Persistent Organic Pollutants (POPs) can alter the hormone homeostasis by mimicking, interfering or blocking the function of hormones; moreover POPs are hypothesized to modify the risk of breast cancer. The association between POPs and breast cancer has been widely studied but the conclusions are inconsistent. The present study examined the associations between serum levels of POPs and breast cancer with focus on the highly exposed Greenlandic Inuit population.MethodsThe study design was a case-control study of Inuit women from Greenland. The participants were asked to complete a questionnaire with information on reproductive history and lifestyle and to provide a blood sample. The sampling was carried out in two time periods (2000–2003 and 2011–2014). The serum levels were determined of 14 polychlorinated biphenyls (PCBs), 11 organochlorine pesticides (OCPs), 16 perfluoroalkyl acids (PFAAs), 1 polybrominated biphenyl (PBB), and 9 polybrominated diphenyl ethers (PBDEs). Independent samples t-test was used to compare differences between cases and controls and odds ratios (OR) adjusted for identified confounders were obtained using logistic regression.ResultsThe study population included 77 breast cancer cases and 84 controls. The majority of the measured compounds declined significantly from 2000 – 2003 to 2011–2014. However, for the perfluorinated carboxylic acids (PFCAs) an increase was observed. The serum levels were significantly higher in cases compared to controls for the majority of the compounds, and after adjusting for age the difference was maintained for ∑OCP, dichlorodiphenyldichloroethylene (p,p′-DDE), ∑PFAA, ∑perfluorinated sulfonic acids (PFSA), perfluorohexane sulfonate (PFHxS), and perfluorooctane sulfonate (PFOS). For the lipophilic POPs, high serum levels (middel/highest vs. lowest tertile) of ∑PCB, ∑estrgoenicPCB, PCB99, PCB138, PCB153, PCB170, PCB170, and PCB183 was associated with breast cancer risk; for the amphiphilic PFAAs, high serum levels of ∑PFAA, ∑PFCA, ∑PFSA, perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), PFHxS, and PFOS were associated with breast cancer risk.ConclusionSignificant, positive associations between breast cancer risk and PCBs and PFAAs were observed. The associations indicate that environmental exposure to POPs can be a factor increasing the risk for breast cancer in Inuit women.Electronic supplementary materialThe online version of this article (doi:10.1186/s12940-017-0269-6) contains supplementary material, which is available to authorized users.

Perfluorinated alkylated substances serum concentration and breast cancer risk: Evidence from a nested case‐control study in the French E3N cohort

“…All cases and 31 controls from our study were then included in a larger case-control study which involved overall 97 BC cases and 93 controls from the Inuit population. 16 This second study found a positive association between both PFOS and PFOA serum levels and BC risk, with no difference between ER− and ER+ cases. Although pointing toward the same results, when comparing these studies with our, some differences in the study design and in the study population have to be considered.…”

“…A case‐control study including 31 BC cases and 115 controls, selected from an Inuit population in Greenland, found that BC risk was positively associated with PFOS serum concentrations, although no stratification according to hormone receptor status was performed. All cases and 31 controls from our study were then included in a larger case‐control study which involved overall 97 BC cases and 93 controls from the Inuit population . This second study found a positive association between both PFOS and PFOA serum levels and BC risk, with no difference between ER− and ER+ cases.…”

Serum Levels of Commonly Detected Persistent Organic Pollutants and Per- and Polyfluoroalkyl Substances (PFASs) and Mammographic Density in Postmenopausal Women

“…Data on other classes of POPs such as polybrominated diphenyl ethers (PBDEs) and per-and poly-fluoroalkyl substances (PFASs) remain scarce and inconsistent [12][13][14][15][16][17][18][19][20][21][22]. Five studies using post-diagnostic samples have investigated serum or adipose-level PBDEs in relation to breast cancer risk [12,[14][15][16]22].…”

“…Whereas positive associations were reported for a few PBDE congeners such as BDE-47, BDE-100, and BDE-153 in an area in China highly contaminated from electronic waste recycling [12], and suggestive positive associations were reported for BDE-47 in Alaska Native women [15] and young Canadian women [22], two studies conducted among general populations in California [14,16] reported no associations. Results on PFASs have also been mixed, with studies reporting positive associations for five PFAS compounds among Greenland Inuits [20], weak positive association for a PFAS compound perfluorooctane-sulfonamide (PFOSA) and non-significant inverse association for another PFAS compound among Danish women [17], and a positive association with estrogen receptor-positive breast cancer for perfluorooctane sulfonate (PFOS) in French women [21]; in addition, no associations were found for perfluorooctanoic acid (PFOA) in two studies conducted in an area near a chemical plant [18,19], nor for six PFAS compounds commonly detected in the general population in California [13]. Little is known about the role of these chemicals with respect to pathological changes along the cancer development pathway or cancer treatment.…”

“…Little is known about the role of these chemicals with respect to pathological changes along the cancer development pathway or cancer treatment. A major limitation common to many of these studies is the use of post-diagnostic samples for cases [13][14][15][16]20,22], with some studies using post-treatment samples [13,14].…”