OWW I'm going to suggest looking at it from a very different perspective. If I've read this right, LM has had surgery and is awaiting the results. He may have cancer, it may be terminal (or not), it may require a delibitating treatment schedule (or not), he may be lucky and the operation is all he required (or not). What I'm trying to say is that whilst you have all that type of shit running around your head, dating ... seems wrong. You have no idea whether you have anything to offer that other person, whether you even have a future to share with them.
You really need to allow him to get his results, to know what he has to deal with before you can decide if a) you are in it for the long haul or b) its all too much. If its a), you can then be firmly re-assuring of your feelings and commitment, if its b), you'll be grateful he's been smart enough not to make assumptions.
Really & truly, this is not about you. He has some potentially serious shit going on here. Don't push it, unless you are 100% confident you are in it for the long haul even if it results in the worst of outcomes. Express your concern & affection, check when he will be seeing his consultant for follow-up/results, but make no demands on him.
BTW, I say this from the perspective of someone who has been where LM is now ... and I'm also sending un-MN hugs to you, its a tough time, but don't expect him to be thinking normally or clearly in the circumstances. The man I'd started seeing shortly before my diagnosis was resolute that he was in it for the long haul so when the relationship ended after my treatment, I fell apart in a big way. LM has to bear that possibility in mind on top of everything else ... its a really hard time for him (and not easy for you).