Not necessarily. Elevated WBC are usually a sign of infection or inflammation, although this can also be seen with leukemia or myeloproliferative disorder. What kind of cancer did you have in the past? Are you also experiencing any constitutional symptoms (e.g., fever, night sweats, and/or weight loss)? Are any of your tumor markers elevated? It is recommended that you see a hematologist/oncologist for further workup and evaluation.
Lymphocytosis (increase in relative or absolute lymphocyte count) can occur in patients with pertussis, syphilis, viral infections, hypersensitivity reactions, and certain subtypes of leukemia or lymphoma.
Best way to know if you've cancer or not is to get an immediate appointment with the specialist and get a consultation.
Well, if you've a cancer history then there are few chances that may be diagnosed with cancer again but not necessarily. So, it is better to check with your doctor to avoid future risks.