Abstract
BackgroundTo assess the importance of heredity in the etiology of inflammatory breast cancer (IBC), we compared IBC patients to several carefully chosen comparison groups with respect to the prevalence of first-degree family history of breast cancer.MethodsIBC cases (n = 141) were compared to non-inflammatory breast cancer cases (n = 178) ascertained through George Washington University (GWU) with respect to the prevalence of first-degree family history of breast cancer and selected environmental/lifestyle risk factors for breast cancer. Similar comparisons were conducted with subjects from three case–control studies: breast cancer cases (n = 1145) and unaffected controls (n = 1142) from the Cancer Genetic Markers of Susceptibility (CGEMS) study, breast cancer cases (n = 465) and controls (n = 9317) from the Women’s Health Initiative (WHI) study, and ovarian cancer cases (n = 260) and controls (n = 331) from a study by University of Toronto (UT).ResultsThe frequency of first-degree breast cancer family history among IBC cases was 17.0 % compared to 24.4 % for GWU breast cancer cases, 23.9 % and 17.9 % for CGEMS breast cancer cases and controls, respectively, 16.9 % and 12.6 % for WHI breast cancer cases and controls, respectively, and 24.2 % and 11.2 % for UT ovarian cancer cases and controls, respectively.IBC cases had a significantly lower prevalence of parous women than WHI breast cancer cases (OR = 0.46, 95 % CI:0.27–0.81) and controls (OR = 0.31, 95 % CI:0.20–0.49). Oral contraceptive use was significantly higher among IBC cases compared to WHI breast cancer cases (OR = 7.77, 95 % CI:4.82–12.59) and controls (OR = 8.14, 95 % CI:5.28–12.61). IBC cases had a significantly higher frequency of regular alcohol consumption (≥1 drink per day) compared to WHI controls (OR = 1.84, 95 % CI:1.20–2.82) and UT controls (OR = 1.86, 95 % CI:1.07–3.22) and higher (statistically non-significant) prevalence (21.3 %) compared to breast cancer cases from GWU (18.2 %) and WHI (15.2 %).ConclusionsThe prevalence of first-degree breast cancer family history among IBC cases was lower compared to breast and ovarian cancer cases but higher than unaffected individuals. Our multiple-case inflammatory and non-inflammatory breast cancer families may reflect aggregation of common genetic and/or environmental factors predisposing to both types of breast cancer. Our findings that oral contraceptive use and regular alcohol consumption may be associated with IBC warrant further investigations.
Highlights
To assess the importance of heredity in the etiology of inflammatory breast cancer (IBC), we compared Inflammatory breast cancer (IBC) patients to several carefully chosen comparison groups with respect to the prevalence of first-degree family history of breast cancer
The prevalence of first-degree breast cancer family history among IBC cases was lower compared to breast and ovarian cancer cases but higher than unaffected individuals
Comparisons revealed nearly similar frequency of first-degree family history of breast cancer among IBC cases compared to Women’s Health Initiative (WHI) breast cancer cases (16.9 %), BRCA-negative ovarian cancer cases (18.3 %), and Cancer Genetic Markers of Susceptibility (CGEMS) controls (17.9 %), and higher prevalence compared to University of Toronto (UT)-controls (11.2 %) and WHI controls (12.6 %) (Table 1)
Summary
To assess the importance of heredity in the etiology of inflammatory breast cancer (IBC), we compared IBC patients to several carefully chosen comparison groups with respect to the prevalence of first-degree family history of breast cancer. The etiologic components of IBC are generally unknown and the contributions of hereditary versus environmental/life style factors remain subject of controversy in the literature. Case reports and case-case studies of IBC have reported associations with factors such as early age at first birth [8, 9], high body mass index (BMI) [10, 11], trauma [12], and longer duration of breast feeding (hypothesized to increase risk through an estrogen surge) [9]. Reports of IBC clusters [8, 13], seasonal variations in the risk of IBC [14], higher occurrence in rural versus urban settings [15], and declining incidence with improving socioeconomic status [7] further highlight the role of environmental factors in the etiology of IBC. Genetic influences play a role in susceptibility to other malignancies with a major environmental component, such as lung and colorectal cancers [17,18,19,20]
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