In terms of gendering suspense, I think it is invaluable. It signifies to the reader that a particular thing is important and it raises tension so that the reader keeps the pages turning. I think foreshadowing is used to some degree or another in all romantic thrillers. It can be as subtle as an atmosphere or as obvious as a piece of information or an object of interest.
As writers we may shorten sentences and paragraphs, speed up speech and ratchet up the action to indicate that things are rising to a climax or something important is about to happen. In films, we are all familiar with the notion of background music telegraphing turning an ordinary event into something sinister. This too is foreshadowing although one could think of it as creating a sense of foreboding.
The main thing about foreshadowing is that we use it early in a piece of fiction and then deliver on the promise later in the story. It is a skill that takes a degree of practise, I feel, in order for it to not appear obvious. The reader should have an ‘ah ah!’ moment later in the story and it should come as a bit of a surprise - if it’s done correctly. But one that when they look back, they see it was correctly done and they were not hoodwinked. The other thing is that if, for example, you show a gun early on in a story the reader will expect it to go off at some point later. So then you are using reader expectation to foreshadow and event for later in the tale.