Nanotechnology has revolutionized different directions of nanobiomedicine, presenting novel opportunities for imaging, diagnosis, drug delivery, and therapy. Cancer is one of the most significant reasons of death in the world. The recent increase in the incidence of cancer and the mortality rates associated with this disease has led to the development of real and rapid early diagnosis techniques for various types of cancer. Sensor systems can be utilized prosperously in the medical area, especially in oncology investigations. On the other hand, traditional techniques utilized for the detecting of cancer, involving magnetic resonance imaging, computerized tomography scan, positron emission tomography scan, bone scan, X-ray, ultrasound, and endoscopy and also immunological and histopathological methods, generally comprise high costs and complicated operation duration, also necessitating complex and expensive equipment. The early diagnosis of a pathology provides feasible to limit effects of disease and to commence the convenient cure as soon as possible. In this regard, there is an exigent requirement for developing new diagnostic apparatus. Biomarkers are overexpressed in the malignant tissues so they can be quantitatively measured in the tumors and body fluids so that appraised as an indicator of pathogenic processes and pharmacologic responses to therapeutic intervention in cancer patients. In this chapter, we discussed the issue of drug delivery, which enables nanomaterials to deliver drugs used in cancer treatment more selectively to target organs or tissues, and the use of these materials, especially in sensor systems that enable the detection of cancer markers with lower sensitivity, in the light of studies in the literature in the last decade. Finally, a brief of available challenges and future outlook in this encouraging area is emphasized.