What is the theme in A Heartbreaking Work of Staggering Genius by Dave Eggers?

Death is the main theme in the book. The book begins with the death of Dave Eggers' parents. His mother suffered with stomach cancer. Her death was a long, drawn out affair that forced her children to become her caretaker. During her illness, Dave's father was also suffering from lung cancer. The father's diagnosis had taken place long before the mother's and everyone believed he would be okay. However, during a routine visit to the hospital, Dave's father passed away. Five weeks later, Dave's mother died, leaving their four children alone to deal with raising the youngest child, Toph. These deaths were an overwhelming event for Dave and his older siblings, and it colored every aspect of their lives from that point on.