None small cell lung cancer

Hi, I'm new to here
Feb 2009 I was found large tumor in my right upper lope 6cm x 4cm
I finished 06 weeks of radiation and now under 06 rounds of Chemo
Last week I just finished 03 round of Chemo and My Doctor sent me to PET scan
On My PET scan is show the tumor shrunk down to 5cm x 2cm and tumor is no more active ( no more up take ) Because I won't see my Doctor until next 04 weeks , If any one here can tell me If the tumor no longer active ( No more uptake ) what does that mean ?
Thanks