navelbine question

my mom has been on navelbine/gemzar combo since dec 24 of 2003. three weeks on 1 week off - has chemo each friday of the on weeks. had scnas last week. all places smaller. expect for liver where there was no significiant change either way. is keeping her on this combo for now.

I have had 7 doses of navelbine, though with a very conservative onc and only 2 of these have been at full strength. He keeps telling me that navelbine works slowly unlike some of the other chemos and we won't know for 2-3 months if it is clearly working. Is this true?