Cancer cells do create hostile microenvironment (deprivation of nutrients, accumulation of acidity, anoxic habitat). Those cells are not only adapted to this sanctuary environment, blunting of immunity but also, grow, migrate to the distal area (metastasis) and communicate with each other in a unique population structure and organization too (clonal expansion). The adaptation requirements push those types of adaptable cells (cancer cells) to be primitive cells. The prevailing pharmacological approach in treating cancer is developing a chemotherapeutic agent that acts on rapidly proliferating cells that are stuck with normally growing epithelium and bone marrow too. The latter approach has been drafted to work on cellular target under the term of "targeted therapy" believing that each target represents Achilles Heels of cancer. In this article, we try to introduce a new concept of cancer pharmacology, by offering new off-label use of Doxycycline, which is characterized by selective toxicity, as potential anticancer agents. This notion is relying on the absence of taxonomic barriers.
Keywords: Doxycycline, cancer, anoxic habixat, metastasis, deprivation of nutrients, acidity.