2003 Altima rear door frame rust??

ALL, can anyone shed some light on this crisis. Just doing a spring cleaning on my altima and discovered rust on the rear door frame directly behind the window. The seam under the door seal is completely rusted about 3 inches long, both doors. The car is mint, i've owned since new and had rustproofed annually. i think its draft issues, the design sucks air into that section and moisture may build up. dunno. i'm no body man, but is this type of rust fixable or am i looking at a new door. thanks for any help, Kevin