Surgery may improve survival in stage IV HER2+ breast cancer
Women with stage IV HER2+ breast cancer who undergo surgical treatment may have improved survival outcomes, suggests a retrospective study presented at AACR 2019.
Using data from the National Cancer Database, researchers identified 3,231 women diagnosed with HER2+ stage IV breast cancer between 2010 and 2012. A majority of the patients received chemotherapy or immunotherapy (89.4 percent), while 37.7 and 31.8 percent received endocrine therapy and radiation therapy, respectively. Thirty-five percent of patients (n=1,130) underwent primary site surgery. The patients were followed up for a median 21.2 months.
Patients who underwent surgery had a greater likelihood of survival compared with those who did not undergo surgery (median, 25 vs 18 months, hazard ratio [HR], 0.56, 95 percent CI, 0.40–0.77; p=0.0004). [AACR 2019, abstract 4873/17]
Other factors that influenced survival outcomes were age, with patients aged 40–59 years having better survival outcomes than those aged 20–39 years (HR, 0.004; p<0.0001), receipt of chemotherapy or immunotherapy (HR, 0.76; p=0.008) or endocrine therapy (HR, 0.70; p=0.0006), and being on Medicare or government insurance compared with Medicaid or no insurance (HR, 0.36; p<0.0001).
Conversely, patients who underwent radiation therapy had a poor survival outcome (HR, 1.33; p=0.0009), while those with visceral metastasis had a poorer survival outcome compared with those with bone-only metastasis (HR, 1.44; p=0.0003). Annual income and race also had an impact on survival outcomes, with those in the lowest income bracket having poorer survival than those in the highest bracket (HR, 1.36; p=0.01) and Black patients having poorer survival than Caucasian ones (HR, 1.39; p=0.002).
Comorbidities, oestrogen or progesterone receptor status, and clinical tumour or nodal stage had no effect on survival.
Women who underwent surgery were younger than those who did not (mean, 56 vs 59.1 years; p<0.0001) and were more likely to have undergone radiation therapy (odds ratio [OR], 2.10, 95 percent confidence interval [CI], 1.76–2.51), chemotherapy or immunotherapy (OR, 1.99, 95 percent CI, 1.47–2.70), or endocrine therapy (OR, 1.73, 95 percent CI, 1.40–2.14). Women who had private (OR, 1.93, 95 percent CI, 1.53–2.42) or Medicare/government insurance (OR, 1.36, 95 percent CI, 1.03–1.81) were also more likely to undergo surgery than those with Medicaid insurance or uninsured women.
In contrast, older women were less likely to undergo surgery than younger women (OR, 0.75, 95 percent CI, 0.56–1.00 [age 40–59 years] and OR, 0.58, 95 percent CI, 0.42–0.81 [age ≥60 years] vs age 20–39 years), as were women who were oestrogen receptor-positive (OR, 0.63, 95 percent CI, 0.50–0.80), women with tumour stages T3 or T4 (OR, 0.73, 95 percent CI, 0.53–0.99 and OR, 0.67, 95 percent CI, 0.51–0.89, respectively, vs T0–T1), and women with clinical nodal stage of N1 (OR, 0.60, 95 percent CI, 0.48–0.74), N2 (OR, 0.72, 95 percent CI, 0.54–0.95), or N3 (OR, 0.67, 95 percent CI, 0.50–0.89 vs N0). Comorbidities and metastasis site had no impact on likelihood of undergoing surgery.
At present, there is no standard surgical treatment offered for women with stage IV breast cancer, with women typically receiving systemic therapy, said study lead author Ross Mudgway, a medical student at the University of California, Riverside School of Medicine, Riverside, California, US.
Surgery or radiation therapy may be offered in a palliative setting to prevent progression, reduce cancer-related symptoms, and improve quality of life, he added.
“[This study shows that] in addition to standard HER2 targeted medications and other adjuvant therapy, if a woman has stage IV HER2+ breast cancer, surgery to remove the primary breast tumour should be considered,” said study senior author Professor Sharon Lum from Loma Linda University Health, California, US.
“Surgery should be discussed with patients as an option that may provide longer survival when considered alongside targeted therapy and other standards of care,” said Mudgway.
However, the impact of race and insurance status on survival point to “disparities in health care due to race and socioeconomic factors”, both of which need addressing, he added. He also called for subgroup analyses of patients with HER2+ disease in studies assessing the impact of surgery in stage IV breast cancer.