Researchers with the SWOG Cancer Research Network have discovered that patients with metastatic hormone receptor-positive breast cancer who have low activity levels of the enzyme sTK1 in their blood serum at the start of anti-estrogen treatment live longer and go longer without their disease progressing than patients with high levels.The findings of the study were published in the journal 'Clinical Cancer Research'.
The study results suggest that patients with low sTK1 activity levels have a slow-growing disease that can be controlled initially with single-drug endocrine therapy for a prolonged period. It remains to be determined whether these patients gain further benefit from adding a CDK4/6 inhibitor to their endocrine therapy.
The findings come from an analysis of serum samples from 432 women with breast cancer who took part in the S0226 clinical trial, which was conducted by the SWOG Cancer Research Network, a cancer clinical trials group funded by the National Cancer Institute (NCI), part of the National Institutes of Health. "SWOG researchers have demonstrated that a blood serum test can identify which of these patients have a slow-growing disease that might be controlled with a simple aromatase inhibitor pill alone," said Dr Lajos Pusztai, MD, DPhil, professor of medicine (medical oncology) at Yale Cancer Center, who is a co-author on the paper.