Patients with early-stage estrogen receptor (ER)-positive breast cancer who live in low-income neighborhoods may be more likely to have more aggressive tumor biology and significantly lower overall survival than those living in higher-income neighborhoods, according to a new study published by Ma et al in JAMA Network Open.
Study Methods and Results
In the new study, the researchers analyzed data from 119,478 patients diagnosed with early-stage ER-positive breast cancer from 2006 to 2018 using the National Cancer Database. All of the patients were treated with surgery and adjuvant endocrine therapy either with or without chemotherapy. The patient outcomes were tracked until 2021, with a median follow-up of 66.2 months.
Among the patients involved in the study, 68.8% (n = 82,198) lived in neighborhoods above the median U.S. household income of $50,353, and the remaining 31.2% (n = 37,280) lived in neighborhoods that fell below that threshold. The researchers focused on patients’ 21-gene recurrence scores—which revealed a statistically significant relationship between low household income and high recurrence scores.
“We have known that income level increases the incidence of poor-prognosis triple-negative breast cancer,” explained senior study author Anurag Singh, MD, Professor of Oncology and Director of Radiation Research in the Department of Radiation Medicine, Director of the Head & Neck and Lymphoma Radiation Services, and Co-Leader of the Cancer Stress Biology program at Roswell Park Comprehensive Cancer Center. “This is the first data to show that income level impacts survival even in [patients who have early-stage ER-positive] breast cancer with a better prognosis.”
The study data also captured the percentage of adults living in the neighborhood who did not graduate from high school—with a median of 10.9% defined as a low education level. However, the researchers found no association between low education levels and high recurrence scores. In fact, the study included non-Hispanic White individuals with higher education levels who also had private health insurance. The data showed that if those individuals lived in low-income areas, they still tended to have higher recurrence scores and worse overall survival rates—while those with higher income tended to have lower recurrence scores.
Conclusions
The researchers speculated that higher recurrence scores and lower overall survival rates indicated that individuals in low-income households may be less likely to undergo cancer screenings, resulting in delayed diagnoses and worsening of tumor biology.
“[F]inancial distress has been shown to result in increased psychological and emotional distress, poor quality of life, and depression,” noted the investigators, adding that such distress could weaken the p53 tumor protein, which is responsible for preventing the development of tumors, and contributing to “more aggressive tumor biology with distant metastasis.”
The researchers concluded that further research may be needed to better understand the relationship between socioeconomic status and intrinsic tumor biology among patients with early-stage ER-positive breast cancer—and how financial distress may affect the pathways that promote tumor formation.
Disclosure: For full disclosures of the study authors, visit jamanetwork.com.
