Methotrexate dosage question...does 60 per cent really work as fast as 100 per cent for PCNSL

Wylie Eden
Wylie Eden Member Posts: 4

Hi all,

best wishes in your battles and God bless...


My dad, 73, has been diagnosed with PCNSL Fec 27 2015, a 5cm diffuse tumor in his cerebullum.  He was diagnosed without biopsy after much discussion about whether it was PCNSL or Glioblastoma or possibly Astrocytoma. 

After one treatment of 60 per cent MTX a BP Shunt was inserted to relieve pressure in his 4th ventricle. He is on DX 8 mg a day (which of course comes with its own set of benefits and side fx.

We have now progressed through 4 treatments with a 60 per cent dose every 2 weeks of MTX due to my dad's kidney function. Actually, as we've moved forward my dad's hydration levels have improved and thus his kidney function has suggested we could move to 70 per cent, but in an abundance of caution the doctor has preffered to stay the course at 60 per cent, which is something I have silently questioned.

We have just been told of the 'results' of an MRI from May 31 that was compared to an MRI from March. The MRI gave very little information. For starters it made no mention with regards to changes in size. However it noted improvment in one area, and 'enhancement' in another. The oncologist's 'scout MD' suggested that the news was mixed and said they are considering stopping treatment. 

She said that after 4 treatments significant improvement should have been noted on the MRI. 

My sister is a nurse and we both asked what seems an obvious question; If Dad is only getting 60 per cent of a full dose, won't it take longer to see results?

Well, the doctor told us that 60 per cent works the same as 100 per cent? Apparently due to factors unexplained. 

Maybe this is a rant, maybe it's me not accepting the reality of my dad's situation, but what I can't understand is that if your kidney function allows for only 49 per cent of a full dose of MTX they won't even give you treatment, yet my dad is only 11 per cent above that threshold, and yet they somehow expect to see the same results as 100 per cent dose?

None of us here are doctors, but if anyone has any experience regarding what your doctors told you about dosage in relation to effectivness, well, let's just say we could really use some other view points as we examine our next move in terms of Dad's treatment.