The Laws of Medicine By Siddhartha Mukherjee

The Laws of Medicine is a slim volume that eloquently reveals any “laws” that exist in medicine are dynamic, and that the field is ruled more by instinct than by rules.

Written by the Pulitzer Prize-winning author of The Emperor of All Maladies: A Biography of Cancer, the book is packed with elegant prose about the vagaries of medicine. Based on a TED Talk of the same name, The Laws of Medicine shows the relative lawlessness of a field whose “rules” are built on shifting sand.

The author admits that he spent much of his residency on a quest to discover such “laws” so that he could succeed. He writes that he imagined the “rules a young doctor might teach himself to navigate a profession that seems, at first glance, overwhelmingly unnavigable.”

Though his compulsion to discover an infallible source of direction is understandable, the young doctor’s search proves fruitless. Mukherjee determines his own practical guidelines, and outlines these in the book. For example, take Law One: A strong intuition is more powerful than a weak test.

Mukherjee relays a medical mystery to prove his case: a 56-year-old patient who lives in a wealthy neighborhood in Boston, dresses like a banker, suddenly experiences dramatic weight loss and muscle weakness. After thoroughly looking for the obvious culprit--cancer-- the myriad tests come back negative.

It’s only after the doctor finally sees the patient out of context does he suspect that he may be a drug addict infected with HIV, which turns out to be true. “A first test can only be interpreted sanely in the context of prior probabilities.”

“It seems a rule taken from a Groucho Marx handbook: you need to have a glimpse of an answer before you have a glimpse of an answer,” he writes.

Further, Mukherjee emphasizes the importance of the patient history as a critical piece of any diagnosis. To underscore this ideal, he presents “Law Three: For every perfect medical experiment, there is a perfect human bias.”

Every test, he writes, should be backed up by the patient history, the physical examination, and the doctor’s experience and instinct. As an example of a pervasive bias, he cites the radical mastectomy to cure breast cancer. Surgeon William Halsted pioneered the radical mastectomy in the early 1900s as a response to the frequent re-emergence of cancer in other parts of the body after surgery. He believed these recurrences to be the result of “unclean” operations, which led him to try a different, more aggressive approach. By amputating the breast and all the surrounding tissue up to the armpit, he reasoned, he was literally pulling the cancer out of the body by its roots.

He called the surgery “radical,” using a term from Latin that means to pull out by the root. As the surgery became increasingly popular, the word “radical” lost its original meaning. Halsted’s students and patients began to think of “radical” in its second meaning: brazen or bold. Over time, Mukherjee writes, “the word itself metastasized,” thus becoming one of the “most inscrutable forms of bias.”

Who wouldn’t want to take a radical approach against killer cancer? But Mukherjee says in the case of breast cancer, this bias led to the overuse of a traumatic surgery that could easily have been avoided by many women. But it was the most common way to treat cancer for more than 85 years.

“Every science suffers from human biases,” Mukherjee says. In medicine, these biases are particularly acute. The Laws of Medicine gives readers an insight into the medical anomalies that are replete in a constantly evolving field, and the importance of the gut instinct in the minefield of medicine.