Cathy,
Based on the high rate of response to the Doxil+Herceptin combo seen in metastatic breast cancer trials it looks like a good choice for metastatic lung lesions (also shown in in-vitro tests).
I am sure there are several other options should the combo not be good enough.
I found this report of a single case of a good response with a different regimen:
Gan To Kagaku Ryoho. 2003 Jun;30(6):879-82.
A case of recurrent breast cancer with lung metastasis and overexpression of HER2 that responded to UFT and cyclophosphamide combination therapy after sequential treatments with epirubicin, taxanes, and trastuzumab]
[Article in Japanese]
Nishimura R,
Nagao K,
Miyayama H,
Okazaki S,
Nakagawa K,
Fujimura Y.
Dept. of Surgery, Kumamoto City Hospital.
We describe a 57-year-old woman who underwent modified mastectomy for right breast cancer (T2N0M0) with overexpression of HER2, in whom lung metastasis developed 3 years after operation. She received sequential chemotherapy, including epirubicin plus cyclophosphamide, docetaxel, paclitaxel and trastuzumab, but the lung lesion progressed after transiently showing a partial response. Oral treatment with UFT and cyclophosphamide was begun as fifth-line treatment. The lung tumor shrank after 2 months, and a partial response has been maintained during continued treatment with UFT and cyclophosphamide. No adverse effects have occurred. We regard combination therapy with oral UFT and cyclophosphamide to be useful for the management of metastatic breast cancer, even in heavily pretreated cases with overexpression of HER2.