Abstract P3-06-12: Estimating prevalence of stage II-III breast cancer in the United States by treatment and biologic subtypes using oncology clinic data
Authors: Quigley J , Hernandez RK , Pirolli M , Quach D , Liede A 
Published: August 2014

Background:

Breast cancer (BC) is the most common malignancy and the second most common cause of cancer death among women in the US, and the main cause of death in women ages 40 to 49 years. Stage II and III BC are diverse diseases represented by several biologic subtypes with distinct behaviors, which have not been quantified outside of clinical trials or SEER using observational data. Additionally, although guidelines address the use of adjuvant treatment (tx) based on tumor grade, lymph node involvement, tumor size, and whether the tumor expression pattern is consistent with estrogen receptor (ER), progesterone receptor (PR), or Her2 receptor over-expression, there is considerable heterogeneity in clinical practice with respect to the types of tx used for patients with early stage BC. The objective of this study was to estimate the number of women (prevalence) with Stage II and III BC in the US by year, as well as the proportion of patients treated with chemotherapy or biologic tx, stratified by subtype and age using electronic medical record (EMR) data from oncology clinics.

Methods:

The Oncology Services Comprehensive Electronic Records (OSCER) database was used to identify women with early stage BC and ≥1 visit to a clinic in each year, 2009-2012. OSCER captures EMR data on &gt;500,000 cancer patients since 2004 from outpatient community and hospital-affiliated oncology practices across the US. Women with a diagnosis of BC (ICD-9 174) were identified using a 4-year look-back period. Women with stage I disease were excluded due to variability in the use of adjuvant tx. Treated patients were defined as receiving any chemotherapy or biologic tx during the year of interest. Raw counts from OSCER were projected nationally with 95% confidence intervals through direct estimation methods utilizing claims data.

Results: When projected to the US population, the prevalence of women with Stage II or III BC was estimated at 316,827 (311,040 - 322,614), 308,792 (303,267 - 314,317), 317,691 (311,543 - 323,839), and 321,281 (315,470 - 327,092) from 2009-2012, respectively. In 2012, 65% of these women had Stage II disease, 76% were over the age of 50, 30% were Her2 positive (+ve), and 63% were ER/PR +ve (17% were Her2/ER/PR +ve). Approximately 46% of Stage II-III BC patients received treatment in an outpatient oncology clinic (45% of Stage II and 48% of Stage III). The proportion of early-stage BC patients receiving tx was very similar across biologic subtypes. Women 65 years or older were least likely to receive tx (42%) of all strata examined.

 2012 Patients Prevalence% treatedBC Stage II-III32128146Stage II20932745Stage III11195448Her2 Status  Her2 +ve9677451Her2 -ve22450744ER, PR Status  ER, PR +ve20328644ER -ve, PR +ve498952ER +ve, PR -ve3339145ER, PR -ve7961552Age Group  &lt;507608152≥5024520045&lt;6521016948≥6511111242

Conclusions:

This is the first study to estimate diagnosed and treated prevalence of women with Stage II or III BC by hormonal and Her2 status in the US using real-world EMR data. These data suggest that adjuvant chemotherapy or biologic tx is used in approximately 46% of women after BC diagnosis, and women age 65 years or older are less likely to receive adjuvant tx.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P3-06-12.