Differences in Breast Cancer Survival by Molecular Subtypes in the United States

Abstract

Using Surveillance, Epidemiology and End Results cancer registry data, we assessed survival after breast cancer diagnosis among women diagnosed during 2010 to 2013 and followed through December 31, 2014. Breast cancer molecular subtypes defined by joint hormone receptor [HR, estrogen receptor (ER) and/or progesterone receptor (PR)] and HER2 status were assessed. Multiple imputation was used to fill in missing receptor status. Four-year breast cancer-specific survival per molecular subtypes and clinical/demographic factors were calculated. A Cox proportional hazards model was used to evaluate survival while controlling for clinical and demographic factors. The best survival pattern was observed among women with HR/HER2 subtype (survival rate of 92.5% at 4 years), followed by HR/HER2 (90.3%), HR/HER2 (82.7%), and finally worst survival for triple-negative subtype (77.0%). Notably, failing to impute cases with missing receptor status leads to overestimation of survival because those with missing receptor status tend to have worse prognostic features. Survival differed substantially by stage at diagnosis. Among stage IV disease, women with HR/HER2 subtype experienced better survival than those with HR/HER2 subtype (45.5% vs. 35.9%), even after controlling for other factors. Divergence of survival curves in stage IV HR/HER2 versus HR/HER2 subtype is likely attributable to major advances in HER2-targeted treatment. Contrary to conventional thought, HR/HER2 subtype experienced better survival than HR/HER2 in advanced-stage disease. .

Examination of a paradox: recurrent metastatic breast cancer incidence decline without improved distant disease survival: 1990–2011

“…Our observation of decreased HER2 + rMBC incidence in the most recent time period is consistent with reported results of improved long-term outcomes after neoadjuvant/adjuvant treatment with HER2-targeted therapy [26]. Improvements in early disease treatment targeted at hormone receptor and HER2-positive disease have reduced overall distant relapse rates but resulted in a new profile of rMBC disease that may be more aggressive with a higher chemoresistant probability [27, 28]. …”

Breast cancer subtypes among Eastern‐African–born black women and other black women in the United States

“…The primary limitation of the current study is incompleteness of birthplace information. Although multiple-imputation methods have been used previously to correct for missing ER, PR, and HER2 status, 45 we did not impute these because this method has not been fully expanded to the nationwide cancer registry data, and important predictors (eg, survival time) for missing HER2 status were not available in our data. In cancer registry data, birthplace is abstracted by tumor registrars from existing medical records.…”

Breast cancer statistics, 2019

“…Triple‐negative breast cancers have a poorer prognosis compared with other subtypes, in part because this subtype is more likely to be diagnosed at an advanced stage, and the development of targeted therapies has lagged behind . Notably, a recent US population‐based study found that 4‐year relative survival was ≥95% for patients diagnosed with stage I disease across all breast cancer subtypes …”

“…State Variation in Female Breast Cancer Incidence and Mortality Rates and Rate Ratios in White and Black Women and Mammography Screening Prevalence DECEMBER 2019found that 4-year relative survival was ≥95% for patients diagnosed with stage I disease across all breast cancer subtypes 63. Geographic Variations in Incidence, Mortality, and Mammography…”