Going to the doctor

Advice needed please. 
If you have a young autistic adult that you are supporting, and they have a symptom that any (in fact every) doctor would say: ‘get that looked at/checked out by a GP to make sure it’s nothing serious’ but the young adult does not want to go to the doctor, what is the best way to approach helping them with that? When they are totally emphatic that they don’t want to go and see the doctor, but the symptom is one that there is a TINY TINY risk it could be something like cancer? What do you do? 
It’s most likely (by far) that it’s nothing serious but there is a TINY chance that it could be? And the young person hates to be put under pressure of any kind (and I don’t think pressure would help but only stress them out hugely). What do you do in this scenario?