Steve Castellaw got much more than a haircut when he went to see his stylist. He also got the first clue that led to his lung cancer diagnosis.

The real estate broker from Highlands, North Carolina was sitting in the hairdresser’s chair when she pointed out something odd.

“Do you know you have a lump on the side of your head?” the stylist asked, as she guided her client’s hand to a dime-sized bump just above his left ear...