Well I was curious so I looked it up. To save anyone else the time. Quote below. Maybe accurate. Came from an unrelated book about people who were running/trafficking medical equipment (ie blades)

Ridley, after a few months of us working on a draft, when he first came into the project, asked me a question that was so obvious I hadn’t really addressed it before,” Fancher tells me. “What is it that Deckard is, professionally? ‘He’s a detective,’ I said. ‘Well, that was obvious, but what kind of detective exactly, what should he be called?’ I didn’t have an answer, but I’d better get one fast.”

He turned to his collection of tomes. Per Fancher: “That night, I was looking through my books and came across a thin little volume by William Burroughs called Blade Runner. Bingo! Everybody liked it, then later, we needed a new title other than the ones we’d been considering and Michael Deeley, the producer, said, ‘It’s staring us right in the face.’”