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Solvent exposure before first childbirth may elevate breast cancer risk
Women with a family history of breast cancer who are exposed to organic solvents before their first full-term pregnancy appear to be at higher risk of developing hormone receptor-positive breast cancer.
Using data acquired through the Sister Study, which assessed genetic and environmental risk factors for breast cancer and focused on sisters of women with breast cancer who were breast cancer-free at baseline, researchers evaluated 47,661 women with an occupational history of organic solvent exposure.
The researchers collected baseline information about the participants’ occupational use of solvents, including the duration of workplace solvent exposure, frequency of solvent use each week and age at first workplace exposure to organic solvents. Follow-up took place through annual updates and biennial telephone reports or questionnaires. The researchers used multivariable Cox regression analyses to evaluate breast cancer risk, after adjusting for known breast cancer risk factors.
The researchers found that during follow-up, 1,798 women were diagnosed with breast cancer, with invasive disease diagnosed in 1,255 patients. Seventy-seven percent of the invasive tumors were hormone receptor-positive. No correlation was found between the overall risk for invasive breast cancer and lifetime organic solvent exposure (HR=1.04; 95% CI, 0.88-1.24) after adjusting for various confounders.
However, there was an approximately 40% increased risk for estrogen receptor-positive breast cancer in women with children who were exposed to organic solvents in the workplace before their first full-term birth vs. women not exposed to solvents (HR=1.39; 95% CI, 1.03-1.86). Additionally, all clinical laboratory technologists and technicians had a roughly twofold increased risk for estrogen receptor-positive breast cancer (HR=2; 95% CI, 1.07-3.7).
Researchers found an increased risk for estrogen receptor-positive breast cancer among women working as housekeepers or those working in factory settings, but this elevation was not found to be significant.
According to study researcher Christine C. Ekenga, PhD, a postdoctoral fellow in the epidemiology branch of the National Institute of Environmental Health Sciences, these findings may have identified a period of increased risk for hormone receptor-positive breast cancer in women.
“The time between puberty and before first birth is an important period of development when the breast may be more vulnerable to chemical exposures,” Ekenga said in the press release. “We observed that women who started working with solvents before their first full-term birth had a greater risk for breast cancer.”
Disclosure: The researchers report no relevant financial disclosures.