In a Black (no LV) and White (huge LV, 75-90-200 mg/day for continuous 5FU) world, we're gray.
I've had my doubts they know what they are doing with leucovorin, for a while. Given the MTFHR mutations, alongside various individual metabolic divergences with 5FU, the amount of LV and 5,10 methylenetetrahydrofolate build-up might be a problem for many. Yet, part of the other "half" might really need a lot of LV to work.
That would account for some of the differences in 5FU-LV performance vs toxicity. For continuous 5FU, I wouldn't be surprised if 4 - 30 mg of LV per day had an optimum point, adequate for TS binding in up to half the population. This low dose LV issue was never properly addressed by trials in my eyes, but that's how I interpret what data there is. Don't quite have a view for biweekly MTD 5FU tx.
Because of the selective R,S enantiomer uptake, I also suspect that oral LV can be superior to IV LV, more than halfway to levo-leucovorin.
Last edited by rp1954
on Thu Nov 19, 2015 5:15 pm, edited 1 time in total.
watchful, active researcher and caregiver for stage IVb/c CC. surgeries 4/10 sigmoid etc & 5/11 para-aortic LN cluster; 8 yrs immuno-Chemo for mCRC; now no chemo
most of 2010 Life Extension recommendations and possibilities + more, some (much) higher, peaking ~2011-12, taper to almost nothing mid 2018, mostly IV C