Why viewing cancer as an ecosystem could lead to better treatments

Cancer is a disease, or group of diseases, in which some cells proliferate uncontrollably and can spread to other parts of the body. But that description doesn’t reflect how our conception of cancer has changed, says Kenneth Pienta at Johns Hopkins University in Maryland. “People used to view cancer as sort of bad luck: the cancer would just change over time and we didn’t really understand why, or how, or what was driving those changes.”

In the past few years, however, Pienta and others have come to see cancers as akin to organisms themselves, existing in complex ecosystems alongside other cancer cells and host immune cells. Cancer cells compete for access to nutrients, and only the fittest survive. “Cancer evolves in response to changes in its environment,” says Pienta. “If it didn’t, it would die.”

Ultimately, this is the reason why cancer kills so many people. Cancer cells divide rapidly, so random mutations occur often and any that confer an advantage are quickly selected for. “They’re evolving to become the best cancer cell they can become and that typically is bad news for the patient,” says Robert Gatenby, co-director of the Cancer Biology and Evolution Program at the Moffitt Cancer Center in Florida.

What’s more, the hardiest cells are better at getting into the bloodstream and spreading to other parts of the body, a process known as metastasis. “We have got good drugs and initial therapies for most types of cancers,” says Gatenby. “But in the metastatic setting, you’re almost never cured.”…