A study appearing in this week's New England Journal of Medicine may deal a massive blow to the field of personalized cancer treatment and to the hopes of doctors and patients alike.
Researchers at Cancer Research UK London Research Institute have discovered that the hopes of taking a tumor biopsy and basing treatment on that sole biopsy is insufficient because it fails to give an accurate portrait of the tumor's genetic code, as there may be places in the code where different genes are active or are mutated than what is uncovered in the biopsy.
This means that a single biopsy can not possibly represent the full genetic sequence of a tumor, and basing any specific targeted treatment options on it will likely result in relapse.
"The deeper you go, the more you find," said one researcher.
It remains unclear if multiple biopsies would produce anything more workable.
This study focused on kidney cancer but it's not a stretch to imagine this to be true across many if not all cancers.