Sure.  I even thought of posting that, but decided against it.  There
is a treatment (or was) when I was a resident (I know, before
telephones), for osteogenic sacrcoma, which was called methotrexate
with folic acid save.  The patients were given a lethal dose of
methotrexate, which was supposed to be high enough to kill every cell
in their bodies, including the cancer cells.  Because cancer cells
divide more quickly than others, they would take up the methotrexate
first (I think this was the rationale), and then a few hours later, we
would give the patient a large dose of folic acid, and that would
block the effect on the rest of his cells.

Your idea seems a good one.

Jack Newman, MD, FRCPC