A cluster of inflammatory breast cancer (IBC) in an office setting: additional evidence of the importance of environmental factors in IBC etiology.

We investigated a cluster of three cases of inflammatory breast cancer (IBC) diagnosed within 10 months in an office setting of 24 people. Information about medical history, pregnancy history, family history of breast cancer, oral contraceptive use/hormone replacement therapy, exposure to possible oncogenic agents and tumor promoters were obtained to determine whether there were differences in risk factors for IBC between cases and controls. The physical environment and location of the cases' office raised concern about air and water quality as well as radiation as being contributory risk factors for developing IBC. Of the three women with IBC, two had high exposures to pesticides/herbicides, all three used oral contraceptives and two used hormone replacement therapy at the time of diagnosis, two had a family history of breast cancer, and two were obese. Among fifteen controls four had pesticide/herbicide exposure, one had a family history of breast cancer, nine used oral contraceptives, seven used hormone replacement therapy, and five were obese. No specific environmental causes were established for this cluster. Several promoting factors have been suggested that could result in subclinical breast cancer emerging as IBC. Among them are exogenous hormones and exposure to herbicides/pesticides.