This qualitative study found that oncologists viewed omission of SLNB in women 70 years and older with cT1N0 HR-positive, ERBB2-negative breast cancer as a nuanced decision that was based on multiple disease- and patient-level factors and that the multidisciplinary nature of current cancer care may be a complicating factor in surgical decision-making. This evidence concerns the gene ERBB2 and breast cancer.