Arsenic

Arsenic gets a bad rap. Sure, it’s a carcinogen, and long-term exposure to high concentrations is a death sentence. But the 2,400-year-old Chinese medicinecould be the key to treating breast cancer, according to a groundbreaking study by University of California, Berkeley researchers.

Scientists from the university’s Arsenic Research Program conducted a massive longitudinal study on women from a region in northern Chile that, for a time, had extraordinarily high levels of arsenic in its drinking water. They found rates of breast cancer dropped by up to 70 percent compared with another region whose water had normal arsenic concentrations. The results were “completely unexpected,” lead author Allan Smith, professor of epidemiology at UC Berkeley and director of the Arsenic Health Effects Research Program, wrote in an email.

Smith and his lab examined breast cancer data from 1950 to 2010 in the region, which is the world’s driest inhabited place. In 1958, a new piping system was built in its main city, Antofagasta, and as a result, the concentration of arsenic in the drinking water jumped — to more than 80 times the limit recommended by the World Health Organization. An arsenic treatment plant was installed in 1970. Over those 12 arsenic-laden years, breast cancer plummeted by 50 percent and bottomed out at 70 percent over the last five years. (Other studies found that lung, bladder and kidney cancer ran rampant among the same population.) Back at the lab, the team was able to replicate the arsenic effect, apoptosis (also known as cell suicide), in breast cancer cells.

It won’t be the first time arsenic has been deemed cancer-killing, not cancer-ous. After studies in the 1980s, a form of arsenic called arsenic trioxide has been used successfully to treat relapsed promyelocytic leukemia, a rare and often fatal disease. Recently, arsenic trioxide has also been deployed with promising results against basal cell carcinoma (a skin cancer) and medulloblastoma (a brain cancer), both in animals, according to Philip Beachy, a professor of developmental biology at Stanford, who conducted the experiments. Smith’s study goes against the establishment thinking (and dogma) that “a little is bad, so a lot must be worse,” but “based on what we’ve found, it’s not a stretch at all to say arsenic could treat breast cancer,” Beachy told OZY.

Still, further research is needed to know if what happened in Smith’s lab was the same as what happened in Antofagasta. “The connection is not clear, yet,” cautioned Beachy. And since no other major city on Earth has experienced such high levels of arsenic, the findings can’t be corroborated by other populations. “Plausible” and “potential” are the key words here, but they are said with gusto and optimism. Arsenic, anyone?