If you'd like to understand how HER2+ (pronounced "her two positive") breast cancer is different from other breast cancers, and to understand the experimental drug TDM1 I am taking to treat it, this video about Herceptin is a good place to start.

HER2+ breast cancer is an aggressive, fast-growing form of breast cancer that afflicts around 20% of breast cancer patients. Before the development of Herceptin, a targeted drug to treat it, this kind of cancer was very dangerous indeed.

TDM1 is the next generation of Herceptin that, in addition to clogging up the HER2 receptors like this video describes, also delivers a miniscule but deadly, targeted dose of maytansine, a poison derived from the maytans tree.