Smoker, Depressed, Had Sore Throat, Lump In Throat, Doing Exercise. Throat Cancer?

hi doctor, i have been smoking for the past 27 years cos i was living in very depressive conditions. 8 years ago i developed (very) sore throat that does not heal, but i continued smoking my average 16 sticks per day. 1 month ago, i crawled out of my horrible living condition and decided to quit smoking . i could not do it cold turkey. so i used the reduction method. so, from 16, to 10, to 6, to 3. now, i am at 3 a day. my sore throat is gone. but, i feel a lump in my throat (right side) one week ago. my weight is constant. i eat well. i exercise- yoga , taichi and aerobics . could it be throat cancer? i read that throat cancer will not show on blood test, is it true?