Cook pasta shells in boiling salted water for 8 to 12 minutes until tender. Drain and set aside.
Meanwhile, boil chicken breasts in salt water for 15 minutes. Drain, allow to cool and dice into small pieces.
In a frying pan, cook carrots, cabbage and mushrooms in oil for about 5 minutes or until tender, stirring regularly.
Combine chicken, pasta and vegetables together in a large bowl. Add cream cheese, vinegar and sugar, and mix well. Serve chilled.