In 2005, Longo recorded the longest lifespan increase on record by deleting copies of the gene SIR2 in baker's yeast .
Longo also discovered that mice given a high dose of chemotherapy after 48 hours without food continued to thrive, while the same dose killed half the mice fed normal diets and caused lasting weight and energy loss in the remaining survivors .
In human cells, test tube experiments revealed a greater resistance to chemotherapy for healthy cells after a short period of fasting while cancerous cells were reduced .
Longo's proposed idea for protection against chemotherapy is known as "the chemotherapy shield," which might allow oncologists to control cancers, making chemotherapy less toxic to the rest of the body . Human trials funded by the V Foundation for Cancer Research will begin in November of 2008 at the USC Keck School of Medicine.