Explanation of Peto's Paradox: Emergent Supression Mechanism of Stem Cells Dynamics

MARCOS GAUDIANO

Buenos Aires

Congreso; Reunión Conjunta de Sociedades de Biociencias; 2017

SAIC-SAIB-SAI-SAFE-SAH-SAP-SAB-SAFIS-SAA-SAB

The paradox was pointed out by Richard Peto in 1977 and states that at the species level, the probability of carcinogenesis does not seem to increase with the animal size. This is in principle counterintuitive because the more cells compose an organism, the higher should be the chance of the ocurrence of at least one cancerous cell. For instante, massive animals as elephants and some species of whales show a lower risk of cancer than our specie, despite having 100 or 1000 times more cells than us. In addition, massive animals tend to live longer, making the paradox even more intriguing.In a recently published article (M.Gaudiano, Mathematical Biosciences, Vol. 282, págs. 174-180, 2016), it is presented a computational model able to provide an explanation to the paradox, which is based on the following idea: by pure chance, the descendents of a cancerous cell sometimes neither proliferate enough nor reach the thereshold needed to kill the organism. Even an animal can just die of old age, before the cancerous cells that it bears, start to cause health problems. Obviously, this may not have a strong incidence on the human carcinogenesis probability, which is not very low. But, how does this effect depend on the specie?p { margin-bottom: 0.25cm; direction: ltr; color: rgb(0, 0, 0); line-height: 120%; }p.western { font-family: "Times New Roman",serif; font-size: 12pt; }p.cjk { font-family: "Times New Roman",serif; font-size: 12pt; }p.ctl { font-family: "Times New Roman",serif; font-size: 12pt; }