Heng YJ, Hankinson SE, Wang J, et al. - Since the association between modifiable breast cancer risk factors and tumor genomic changes is largely unknown, researchers assessed the link of prediagnostic body mass index (BMI), cigarette smoking, and alcohol intake with somatic copy number variation (SCNV), total somatic mutation burden (TSMB), 7 single base substitution (SBS) signatures (SBS1, SBS2, SBS3, SBS5, SBS13, SBS29, and SBS30), and 9 driver mutations (CDH1, GATA3, KMT2C, MAP2K4, MAP3K1, NCOR1, PIK3CA, RUNX1, and TP53) in a subset of The Cancer Genome Atlas. All women and women with ER(estrogen receptor)⁻ tumors exhibited increasing BMI in relation to increasing SCNV. Higher SCNV and TSMB were seen in smokers vs nonsmokers. Higher SCNV was detected in alcohol drinkers vs non-drinkers. SBS3 was particularly identified in alcohol drinkers with ER− disease. The chance of having GATA3 mutation was more in women with higher BMI. Following multiple testing correction, no link remained significant. This work affords preliminary evidence that breast tumor biology, especially, DNA alterations, can be influenced by BMI, cigarette smoking, and alcohol intake.