HER2 testing differs by age, race, and tumor stage
MedWire News: Adherence to recommendations for human epidermal growth factor receptor (HER)2 testing in patients with breast cancer is high but is not equally applied to women of all ages and races, US researchers report.
Although US year 2000 guidelines recommended characterizing breast cancers by HER2 status, not all national cancer registries collect HER2 data, rendering a population-based understanding of HER2 and clinical ‘triple subtypes’ (estrogen receptor [ER]/progesterone receptor [PR]/HER2) largely unknown, say Mary Jo Lund (Emory University School of Medicine, Atlanta, Georgia) and colleagues.
To better understand the population-based prevalence of HER2 testing and status, triple subtypes and subtype incidence, Lund and team analyzed the medical records of 1842 women with breast cancer in Atlanta.
In all, 90.1% of women received HER2 testing, and 12.6% were positive, 71.7% were negative, and 15.7% were unknown.
HER2 testing compliance was significantly better for women who were younger, of Caucasian or African-American descent, or diagnosed with early-stage disease.
Triple-negative tumors were more prevalent among Black women than White women (26.8% vs 12.4%), and were associated with younger women, and those who were diagnosed with late-stage tumors.
Triple-negative tumor incidence was 27.8 per 100,000 women overall and was higher among Black women than White women (36.3 vs 19.4). These differences persisted when the women were divided into those younger than 50 years, and those aged 50 years and older. HER2-positive tumor incidence (regardless of ER/PR status) was 21.1 per 100,000 women and did not differ by race or ethnicity.
The researchers cautiously extrapolated these incidence rates to give an annual new burden of 3000 HER2+ tumors in Black women, and 17,000 HER2+ tumors in White women in the USA. For triple negative tumors, these figures were 5000 and 16,000 new tumors for Black and White women, respectively.
“As biologic knowledge is translated into the clinical setting eg, HER2 as a biomarker, it will be incumbent upon national cancer registries to report this information,” conclude Lund and co-authors in the journal Cancer.
“Testing, rate, and burden variations warrant population-based in-depth exploration and clinical translation,” they add.
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By Laura Dean