Standard breast cancer classification may overlook important differences

Breast cancer is typically classified as either estrogen receptor-positive or estrogen receptor-negative. However, a new study from Sweden suggests this simplified classification may miss important biological differences between patients, potentially impacting treatment decisions. The study, published in The Lancet Regional Health – Europe, found that tumors expressing estrogen receptors could be further categorized on a spectrum, with varying levels of receptor positivity affecting survival rates.

Tumors with low to moderate levels of estrogen receptor expression had worse outcomes compared to those with higher levels. Patients with mild to moderate levels of estrogen receptors may benefit from a combination of chemotherapy and hormone therapy, indicating that the exact level of receptor expression could be crucial in determining treatment.

The researchers stress that their findings come from an observational study and that further research is needed to apply these results in clinical practice.