By Sue Rochman
What is Cancer?
Cancer is many diseases, but all with common denominators
By Sue Rochman
"You have cancer," you may have heard the doctor say. Or perhaps, "I have cancer," from your spouse, your partner, your parent or your friend. Maybe even, "Your child has cancer."
The words can be numbing, or confusing. And amid all the mixed emotions tied up in a cancer diagnosis, at some point you wonder what happened. We all know cancer means something went wrong inside the body—but what? That something can be very different, yet similar, for each person with the disease. So what really, is cancer?
Individuals who have been diagnosed with cancer share a common bond. And they often think of themselves as having the same disease. Yet the term cancer actually encompasses more than 100 diseases that affect many different tissues and cell types and that have distinct prognoses and treatments. What every cancer has in common, though, is its genesis: All cancer starts as a normal cell that has gone awry. And in the same way that an infant doesn't just get up one day and start walking, a cell doesn't become cancerous overnight. A baby must develop all of the skills necessary to stand, balance and then move to a new spot. In turn, a normal cell must acquire all of the specific traits necessary to achieve the power and potential of a fully realized cancer cell.
A MULTITUDE OF DISEASES
When a person is diagnosed with cancer, two things have happened: The person has cells that are out of control, and these cells are moving into areas where they aren't supposed to go. But not all cancers are the same. "Today we think that there is not just one single thing called cancer but that it is really a group of diseases," says cancer researcher Kristiina Vuori, acting director of the cancer center at the Burnham Institute, in La Jolla, Calif. "The traditional way to classify cancer has been based on anatomical location, like the breast or the prostate." This made sense, because a cancer that develops in one part of the body differs from a cancer that develops in another part of the body. "But we also now realize that anatomy is not the whole story."
Instead, she explains, scientists now understand that each type of cancer "is defined by the molecular mechanisms that cause it." This means that not only does breast cancer differ from prostate cancer, but that not all breast cancers or prostate cancers are themselves the same. "There are many different molecules that can be involved," explains Vuori, "and how the disease develops can vary in many ways." As the saying goes, "all these different roads lead to Rome. But where they begin and how they get there are very different."