ARSENIC: Carcinogen or Anticancer Agent

It has been known for years and repeatedly demonstrated that arsenic is carcinogenic. In fact, recent studies strongly imply that in addition to skin cancers, arsenic may cause internal cancers involving the bladder, liver and lungs. Unfortunately these lesions are not readily differentiated from cancers of these tissues attributable to other causes. Recently, studies by M. Mass of USEPA and others suggest that arsenic reduces or blocks production of the p53 gene product which is a known tumor suppressor. This is in accord with arsenic's general reputation as a cancer "progressor" rather than an initiator.

Strangely, a recent report suggests arsenic trioxide in low doses puts acute promyelocytic leukemia (APL), a rapidly fatal blood cancer, into remission in the majority of cases. The apparent contradiction between carcinogenic and anticarcinogenic behavior is in line with many other treatments for cancer. The purported mechanism for arsenic's affect on APL is that it induces or allows apoptosis of malignant tumor cells. This is interesting, since the p53 gene product functions in inducing apoptosis, again an apparently contradictory role for arsenic.

Chen Zhu, Shang Ting-Dong. In vitro studies on cellular and molecular mechanisms of arsenic trioxide (As203) in the treatment of acute promyelocytic leukemia. Blood. Aug 1 88(3):1052-61. 1996.

Wang, L., BC Roop, JJ Mass. Abstract 449, Supplement, Fundamental and Applied Toxicology, 30, No.1, Part 2. 1996.