All the pink associated with breast-cancer awareness reinforces a common fallacy that drives Virginia Postrel crazy — the notion that breast cancer is one disease:
Five years ago, oncologists had already long understood breast cancer as several different diseases that, based on their underlying molecular behavior, react differently to different treatments. (My own cancer was HER2-positive, an aggressive form found in about a quarter of breast-cancer patients and responsive to Genentech Inc.’s (ROG) biologic Herceptin.)
Now we have even more reason to understand breast cancer as multiple diseases.
An enormous study published last month in the journal Nature analyzed samples from 825 breast-cancer tumors, using five different tests to find mutations in different aspects of their genetics. Researchers crunched the resulting data to classify the cancers into four general types: Luminal A, Luminal B, HER2-enriched, and basal-like. (They also identified a fifth type, dubbed normal-like, but didn’t have enough samples to adequately study it.) Given its underlying genetics, each type might be susceptible to a specific treatment approach.
The study refines the way oncologists understand the different versions of the disease. The biggest news was that the basal-like cancers had more in common with the most common ovarian cancer, called serous, than with other types of breast cancer.
Breast cancer isn’t just more than one disease, it turns out. Some “breast cancer” doesn’t seem unique to breasts.