Our house is 21 years old. Our basement drain backed up 2 weeks ago. The plumber snaked it then using a camera and water cleaned out the line.

2 weeks later we once again had backup, just a small amount from the toilet. After that backup it continued to drain fine. He re-snaked it, but it was not plugged. His camera showed that the main drain, made of cast iron had broken on the bottom of the pipe causing jagged edges. He said this caused things to get caught on it and back up. he is recommening replacing the pipe at mega $$'s but means tearing up a completed basement to get to it. The drain has worked fine except that one time. Can anyone shed some light on this issue?