Why Does a Lower Tumor Burden Improve Cancer Treatment?
Siddhartha Mukherjee says a lower tumor burden raises the chance treatment works because fewer cancer cells are left that can resist the therapy. For the most part, fewer tumor cells mean a better outcome. He names a few exceptions. Papillary thyroid cancer does not seem to matter, and a handful of remarkable checkpoint inhibitors often do not matter either.
Bert Vogelstein gives the arithmetic. Three zeros separate one million from one billion. Start with one billion cancer cells and leave one million, and the count has fallen by one thousand. Mukherjee says that fall reduces, by one thousand, the chance of a cancer cell resistant to the therapy. He calls the change huge.
The same idea sits behind adjuvant therapy, drugs meant to kill cancer cells left after the bulk of a tumor is removed. Mukherjee says a trial is already in the works for patients who still carry a KRAS mutation after a Whipple has taken out most of the visible pancreatic cancer.
