Back to the drawing board: Seeking a common link among carcinogenic factors in the formation of precancerous senescent cells

Our greatest advances against cancer mortality in recent decades has been mainly due to the earlier diagnosis and treatment before it spreads to distant tissues, or the reduction of risk factors to prevent its initiation, while mortality statistics from metastatic disease have remained essentially unchanged over the same period. Flaws in our understanding of the basic biology of malignancies have stymied significant progress in metastatic cancer care. A reexamination of existing data is necessary to provide new insights into the disease. A constantly expanding list of actual and suspected carcinogens — each of which has a different mode of action or effect on cells — causes or contributes to the formation of cancers, but what common process links them? Ultimately, when considering all of the elements as a whole, the unifying characteristic of the multitudes of unrelated carcinogenic factors is to speed the induction and accumulation of precancerous senescent cells within target tissues, where they gradually alter the microenvironment while awaiting priming and transformation to malignancy.