回复：How long can I leave US without abandoning I-485?

Mostly likely, your I-485 may be denied because you are out of U.S. for too long period of time and USCIS might think you have no intent to leave U.S. permanently. Just think about that even if you have a green card, USCIS still may cancel your GC if you stay outside U.S. for more than one year without USCIS permission in advance.