No necessarily. A testicular tumor may be too small to cause a lump but still spread widely. A physical exam may not detect an early testicular cancer.
Yes. Yes testicular cancer could be diagnosed by physical examination, see you physician.
Annual exam. Your annual exam will tell you if there is any suspicion of testicular mass/testicular cancer. Exam alone will not be able to tell you a definite answer whether you have a cancer or not. A series of tests that include sonogram of the testes, blood work- such as Alpha feto protein , b-hcg, other imaging ct/ pet scan etc have to be done--then ultimately orchiectomy will give you a definite answer .
Self exam may be. With no risk factors like family history, previous testicular cancer or cancer in identical twin, undescented testis, male infertility, with out these factors routine screening is not useful, however patient education monthly self examination is helpful in early detection ( not waiting for a year). Testicular cancer is one the caners which has highest cure rate, with life time risk of 0.4%.