CT scan questions for lung mets

I just had my CT scan result, and like to know if anybody with lung mets can help explain the result. After 4 months Novelbine/herceptin chemo, CT scan of 5/20/04 showed less fluid compare to scan of 3/1/04. The 1cm node on the right lung( it was 1 cm in 5/1/03) and the 0.5cm node on the left lung(it was found 0.5cm in 12/30/03)are unchanged. All other small nodes in the lung diminished. The mediastinal nodes desappeared. How to explain those 2 nodes which were stay the same for such a long time? Does this mean the novelbine/herceptin could not knock them down? or may be they are dead tisue there? Any thoughts would be appreciatted. Thanks in advance for all your input!