Delivery of the so-called Tumor Treatment Fields (TTFields) has been proposed as a cancer/ntherapy. These are low magnitude alternating electric fields at frequencies from 100 to 300 kHz/nwhich are applied continuously in a non-invasive manner. Electric field delivery may produce an/nincrease in temperature which cannot be neglected. We hypothesized that the reported results/nobtained by applying TTFields in vivo could be due to heat rather than to electrical forces as/npreviously suggested. Here it is presented an in vivo study in which pancreatic tumors/nsubcutaneously implanted in nude mice were treated for a week either with mild hyperthermia/n(41°C) or with TTFields (6 V/cm, 150 kHz) and tumor growth was assessed. Although the TTFields/napplied singly did not produce any significant effect, the combination with chemotherapy did show/na delay in tumor growth in comparison to animals treated only with chemotherapy (median relative/nreduction = 47%). We conclude that concomitant chemotherapy and TTFields delivery show a/nbeneficial impact on pancreatic tumor growth. Contrary to our hypothesis, this impact is nonrelated/nwith the induced temperature increase.

This research was supported by project grants (AR00311 - MICINN-TEC2010-11182-E, SAF2012-/n33636, RTICCC RD12/0036/0031) from the Spanish government and in part by a Marie Curie grant/n(IRG 256376) from the European Commission and by the Generalitat de Catalunya (2009 SGR/n1356).