Carcinization: Introduction to the Hallmarks of Cancer

     The condition we call cancer has been well documented throughout all of human history. Around 400 BCE, the Greek physician Hippocrates described breast tumors with radiating blood vessels resembling the limbs of a crab or karkinos. But this is hardly the first description of tumors; we've been describing cancer in very similar ways much, much earlier than that. The first known writings from around 2500 BC are attributed to Imhotep, an ancient Egyptian physician and healer. He too describes tumors as firm, bulging masses that were cool to the touch.

     For over 4000 years, scientists and physicians used their eyes to describe cancers (color, shape, size, location) and logically categorized them. A methodology that was, and continues to be useful, but can be unintentionally misleading. Before Charles Darwin, zoologists scientifically grouped animals based on morphology as well. For example, many believed whales and dolphins to be fish, not mammals. The seemingly subtle shift brought about by On the Origin of Species aided in reframing how we think about life from a scientific perspective. But it had another unintended consequence, opening the door to today’s topic: Carcinization.

     Carcinization is an evolutionary process where non-crab animals gain more “crab-like” physical attributes. First recognized in late 19^th century Sri Lanka by post-Darwinian zoologists, the phenomenon is observed across five different groups of crustaceans. Prior to understanding convergent evolution, it was mistakenly believed that all “crab-like” things must be crabs instead of different groups evolving independently toward the “crab-like” design.

     Similar to the fish/mammal distinction for dolphins, this is a seemingly unimportant observation; but for scientific understanding, the implications are monumental. With shifting perspective on classification and massive advancements in laboratory technology, a monumental realization was had: cancer is not a single disease with many manifestations but a collection of diseases with “crab-like” traits. 

     To this end, many scientists set out to elucidate the attributes and behaviors needed for a disease to be classified as a cancer. In less than a century, we advanced further than in the past four millennia combined. In 2000 Douglas Hanahan, PhD and Robert Weinberg, PhD published an eleven-paged paper simply titled “The Hallmarks of Cancer.” Their concise summary laid a new cornerstone for how we view and treat cancer today. In this short series, we’ll take a look at each of the Hallmarks outlined in the original paper and two subsequent updates to better understand the disease and apply that knowledge to modern treatments.