Several strategies have been proposed to control telomerase in cancer cells: anti-sense technology against telomerase RNA component (TR) and telomerase reverse transcriptase (TERT), ribozymes against TERT, anti-estrogens, progesterone, vitamin D, retinoic acid, quadruplex stabilizers, telomere and telomerase targeting agents, modulation of interaction with other proteins involved in the regulation of telomerase and telomeres, etc. However, the transcription control of key telomerase subunits seems to play a crucial role in whole complexes activity and cancer cells immortality. This evidence concerns the gene TERT and cancer.