Is there a way to backup a DC game without a cable or downloading iso's

[BOT]

Yes there is and it is very easy.
First you need to break into SEGA or some other DC software developers premises and steal a GDROM reader/burner, while you are there steal some blank GD-Roms as well.
Then you need to design and build an interface so that you can connect the GDROM reader/burner to your PC.
Next you need to write some drivers so that your operating system knows what this device is and finally design and write a software package to read, copy and burn the GDROM.
Simple!