Boeing lost an order for 35 Dreamliners with a list price of $8.5 billion on Thursday in the biggest cancellation for the 787 jet as Qantas Airways scrapped a contract after delivery delays and losses on international routes.

Qantas’s decision underscores a slowdown in international travel that has caused carriers like Cathay Pacific Airways and Singapore Airlines to cut plans for expansion.

“It’s going to bother people more because of what it says about growth in air travel than because of anything it says about the 787,” Howard Rubel, an analyst with Jefferies & Company.

Qantas will receive $433 million from Boeing in compensation for delays and a refund of deposits for the canceled order, the airline’s chief financial officer, Gareth R. Evans, said.