ImportanceThere are well-known differences in patient outcomes and effective therapeutic options across subtypes of breast cancer (BC), defined by the status of estrogen receptor, progesterone receptor, and erb-B2 receptor tyrosine kinase 2 (ERBB2 [formerly HER2]) expression, making testing for these receptors part of the routine workup for all patients with a diagnosis of invasive BC. Despite its importance, this information is missing in some BC cases.ObjectiveTo identify female patients with BC without record of testing for estrogen receptor, progesterone receptor, or ERBB2 status, defined as missing components of receptor status (MCRS).Design, Setting, and ParticipantsThis cross-sectional study used data from National Cancer Institute’s Surveillance, Epidemiology and End Results Program of 18 population-based registries from women with a diagnosis of invasive BC (excluding death certificate–only and autopsy cases) from January 2012 to December 2016. The final analyses were completed in February 2022.Main Outcome and MeasureThe primary outcome was MCRS. Those with MCRS were summarized by age, race, stage at diagnosis, reporting source, primary payer, and geography. Multivariable logistic regression was used to estimate adjusted odds ratios (aORs) for MCRS.ResultsOverall, 321 913 patients with invasive BC were included (1928 [1%] American Indian or Alaska Native, 28 173 [9%] Asian or Pacific Islander, 36 357 [11%] Black, and 252 447 [78%] White individuals); of these, 15 250 (4.7%) had MCRS. The multivariable model showed that the odds of MCRS were higher in women 80 years or older compared with those younger than 49 years (aOR, 1.75; 95% CI, 1.65-1.88), Black compared with White women (aOR, 1.09; 95% CI, 1.00-1.16), and those with distant stage or unknown/unstaged cancer at diagnosis compared with a local stage at diagnosis (aOR, 3.33; 95% CI, 3.17-3.50; and aOR, 19.39; 95% CI, 18.15-20.72; respectively). With hospital inpatient/outpatient or clinic as the reference group, cases reported by laboratory only, nursing/convalescent home/hospice, and a physician’s office were more likely to have MCRS (aOR, 1.42; 95% CI; 1.28-1.60; aOR, 9.37; 95% CI, 6.03-14.53; and aOR, 2.32; 95% CI, 2.06-2.62; respectively). Adjusted odds of MCRS were higher for the categories of insured/no specifics and insurance status unknown compared with those who were insured. The adjusted odds of MCRS were higher in rural compared with urban areas (aOR, 1.08; 95% CI, 1.03-1.15).Conclusions and RelevanceThe results of this cross-sectional study of women with a diagnosis of invasive BC suggest that despite a standard of care recommended by all expert guidelines, there needs to be greater focus on hormone receptor and ERBB2 testing in all women with invasive BC. The results of this study may help clinicians, public health practitioners, and policymakers target affected populations to minimize or eliminate this critical health disparity and help save more lives.