i'm 35. Just had a physical for my new job I'll start in about 2 weeks. every checked out great, even my nuts since some old ugly broad held them and I coughed.
i highly recommend getting checked once a year, if only blood work, piss, and blood pressure. the best thing to do is do the works once a year: blood pressure, blood work, piss, stress test, everything. I had all of it done once when I was having chest pains. turns out i'm fit as a fiddle, just have really bad stress and anxiety. that stress test is no joke.
unfortunately, there is no way to detect cancer unless you want to pay an assload for full body scans. you literally have to wait for cancer to start fucking you up