A new large-scale study published on the website of the Yale School of Medicine found that the use of alternative treatments in breast cancer is associated with lower patient survival.

Analysis of data from more than 2.1 million women with breast cancer showed that those who used so-called complementary and alternative medicine (CAM) had worse survival outcomes compared with patients receiving standard treatment.

These approaches include dietary supplements, meditation, yoga, acupuncture, and other non-medical practices. Importantly, the study does not claim that these methods are inherently harmful.

The problem lies in the fact that patients who choose these therapies often refuse or delay evidence-based treatments such as surgery, chemotherapy, radiation, or hormone therapy.

As a result, it is this reduction or delay in standard treatment that is linked to poorer prognosis. For example, five-year survival among patients using alternative methods was significantly lower than among those undergoing conventional therapy.

Breast cancer is one of the most studied cancers, and survival rates have improved substantially over the past decades due to early diagnosis and the development of targeted therapies. However, rejecting these proven methods in favor of alternative practices can undermine these advances.

It is important to understand the distinction: modern medicine allows the use of additional therapies—for instance, to reduce stress or improve quality of life—but these are considered supplements, not replacements, for primary treatment.