Environment and Breast Cancer: Science Review


Evidence From Humans
 
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The organochlorine pesticides residues in the invasive ductal breast cancer patients
Yang, J. Z., Wang, Z. X., Ma, L. H., Shen, X. B., Sun, Y., Hu, D. W., Sun, L. X. Environ Toxicol Pharmacol. 2015. 40:3, 698-703.
Topic area
Environmental pollutant - OCPs
Study design
Hospital based case-control
Funding agency
Hebei Province Science and Technology Guidance Pro
Study Participants
Number of Cases
Cases: 75 patients with invasive ductal carcinoma
Menopausal Status
The menopausal status of women included in this study is listed here.
No analyses based on menopausal status
Number of Controls
Controls: 79 with patients with benign breast disease and 80 healthy controls
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
Women aged 25-70 were recruited from the Affiliated Hospital of Chengde Medical College from 2005-2006. Participants were local to Chengde in China, and had no hormone administration within 3 months, oral contraceptive use within 1 year, did not have other tumors, and did not have occupational exposures to OCPs. Women who had distant metastasis or were extremely ill or near death were excluded. Eighty healthy women (based on medical examination) and 154 women with pathologically confirmed breast disease (invasive ductal carcinoma or benign breast disease)
Comment about participation selection
Excluding women with occupational exposures to OCPs likely reduces variability in participants' exposures and may particularly limit opportunity to study women with high exposure. The lack of information about control selection limits interpretation of this study.
Exposure Investigated
Exposures investigated
Breast adipose tissue and serum levels of organochlorine pesticides HCH, alpha-HCH, beta-HCH, gamma-HCH, delta-HCH, PCNB, PCA, PCTA, pp'-DDT, pp'-DDE, pp'-DDD, op'-DDT.
Exposure assessment comment
Serum was obtained from fasting blood samples. Treatment status for cases not specified.
Breast cancer outcome investigated
Primary incident breast cancer
Confounders considered
Other breast cancer risk factors, such as family history, age at first birth, and hormone replacement therapy use, that were taken into account in the study.
Not clear. The distribution of several characteristics (age, BMI, etc.) were very similar across cases and controls, suggesting matching, but this is not described.
Genetic characterization included
If the study analyzed relationships between environmental factors and inherited genetic variations, this field will be marked “Yes.” “No”, if not.
No
Strength of associations reported
Mean blood levels of OCPs (μg/L) in breast cancer cases compared to women with benign breast disease:
β-HCH: control mean = 0.60, case mean = 3.42
PCTA: control mean = 1.63, case mean = 6.83

Mean adipose tissue levels of OCPs (μg/kg) in breast cancer cases compared to women with benign breast disease:
β-HCH: control mean = 57.84, case mean = 219.34
pp'-DDE: control mean = 39.80, case mean = 161.60
PCTA: control mean = 0.89, case mean = 6.05

Mean blood levels of OCPs (μg/L) by tumor subtype:
β-HCH: ER- mean = 2.31, ER+ mean = 3.72
PCTA: ER- mean = 5.20, ER+ mean = 7.14

Mean adipose tissue levels of OCPs (μg/kg) by tumor subtype:
β-HCH: ER- mean = 141.92, ER+ mean = 238.78
pp'-DDE: ER- mean = 157.74, ER+ mean = 175.87
PCTA: ER- mean = 5.07, ER+ mean = 7.68

Blood and adipose tissue levels of β-HCH and PCTA and adipose tissue levels of p,p'-DDE in cases increased with tumor degree ('degree' is not explicitly defined but likely referring to tumor stage).
Results Comments
The author report almost all of these comparisons as statistically significant, however the tests employed (t-tests, ANOVA) require assumptions of normality whereas environmental chemicals often show a skewed distribution. There is no mention of log transformation. If the data violate the assumptions of the tests p-values are not valid, so we have not included them here.
Author address
The Affiliated Hospital of Chengde Medical College, 36 Nanyingzi Street, Chengde 067000, Hebei, China. The Affiliated Hospital of Chengde Medical College, 36 Nanyingzi Street, Chengde 067000, Hebei, China. Electronic address: dawei.hu@163.com. The Affilia
Reviewers Comments
Only β-HCH and PCTA were sufficiently detected in serum for analysis, while DDT metabolites have high detection frequencies in other studies in China. Detection limit was not provided, so perhaps the analytical methods were not sensitive.