Tuesday, January 5, 2010

Arsenic, our friend? Arsenic as chemotherapy.

Recently, in the process of caring for a patient with leukemia, I was reminded by the oncologist of arsenic as a treatment option for certain leukemias. That's right, arsenic...

ar·se·nic (√§rs-nk)

  1. Symbol As, A highly poisonous metallic element having three allotropic forms, yellow, black, and gray, of which the brittle, crystalline gray is the most common. Arsenic and its compounds are used in insecticides, weed killers, solid-state doping agents, and various alloys.

Chemotherapy in today's age is to a large degree still poison - potentially effective poison in extending patients lives but poison nevertheless. Therefore, to be receiving arsenic, in the eyes of you and your oncologist the benefits outweigh known toxicity and risks. However, the idea of arsenic as a chemotherapy can be a tough one to swallow.

As far as medicine has come over the years (and it has become quite advanced in certain regards), medicine still has a long way further to advance – an idea that can be forgotten by the lay population. Our expectations in a society now with ubiquitous iPhones and Wifi internet on airplanes may not carry over well to medicine. Certain successes in medicine, such as pacemakers or heart transplants, may have helped create this impression. The reporting of medical news by the lay press often reinforces it, feeding unrealistic expectations by its tendency or bias towards portraying miraculous success stories, early technological breakthroughs, or early, intriguing but unconfirmed experimental results.

And then there is arsenic as an addition to standard chemotherapy or a second or third line agent in the treatment of various leukemias.

Arsenic in our environment is found in both natural and industrial sources but as it can be poisonous, particularly with chronic exposure (arsenic poisoning is a serious health problem in various part of the world), our exposure is regulated by the government. For example, the Maximum Contaminant Level (MCL) of arsenic in drinking water is currently set by the EPA at 10 micrograms per liter of water.

On a given day we may ingest up to a few hundred micrograms from our water or food. The amount of arsenic given with each daily infusion of chemotherapy to the average male (~70 kg in weight) might equal 10.5 milligrams (mg) – on the order of 100 times more than our daily intake.

Which is not to say I wouldn't take arsenic if it were indicated or recommended by my doctor given my medical condition. I merely think people might appreciate this perspective on medicine.

A similar example in cardiology and primary care

A similar example would be Warfarin - initially marketed as rodent poison but used in medicine since the 1950s and remains today the most prescribed anticoagulant in the United States with increasing numbers of prescriptions written to treat various blood clotting disorders, such as atrial fibrillation (a type of irregular heart beat), pulmonary emboli (clots in the lungs), and deep vein thrombosis (clots in the legs).

Can you think of other examples?