Just noticed during my last few phyisicals, my wbc has been low. 4.1 in may 2016, 4.5 in 2015 and 4.8 in 2013. 2 doctors and a np didn't seem worried. whenever i look online it says could be cancer. why isn't it a concern?

It Depends.: Some medications may cause this low white blood cell count, also called, leukopenia. Lipitor is one of them. A patient's race may also play a factor. African American populations may have lower WBC counts. As long as you are not prone to getting infections. Your count seems adequate and as long as when you do get an infection your body mounts a reponse you should be fine.

Leukopenia: This may be benign leukopenia with borderline low wbc. If the other bone marrow elements-red blood cell and platelet counts- are normal, no evident serious blood dyscrasia is evident. Sometimes mild leukopenia is seen in autoimmune disorders like lupus. A hematologist is best qualified to evaluate,advise and follow-up with periodic blood tests(cbc, differential and platelet count)