We're all familiar with the trajectory of cancer: It grows, evades our defenses and spreads throughout the body.
Two influential researchers are now updating the way we understand this disease. Douglas Hanahan, of the École Polytechnique Fédérale de Lausanne in Switzerland, and Robert Weinberg, of the Massachusetts Institute of Technology, explain emerging concepts in the study of cancer, in a paper published today (March 3) in the journal Cell. Their paper highlights progress in the field and hints at promising strategies for treatments.
In 2000 the duo published a landmark review paper about the hallmarks of cancer that became the most cited article in the same journal.
"They're really unparalleled in doing this — capturing hypotheses that relate to the whole network of events that are central to cancer," said Dr. Stephen Baylin, an oncologist at Johns Hopkins University.
In their latest paper, Hanahan and Weinberg add a few characteristics of cancer that are central to understanding the disease's destructive path . For one, they note that cancer cells adjust their metabolism to meet the energy needed for their incessant replication.
Further, the duo explain the push and pull of the immune system on cancer — while some immune responses attack tumors, others nourish them.
For example, certain types of tumors may spring up only when they can avoid detection by the immune system, the authors argue, citing evidence that patients with weakened immunity are more likely to develop cancer.
But inflammation, which is the immune system's natural reaction to infections and harmful substances, produces chemicals that accelerate the rate of mutations in cancer cells , allowing them to gain traits that promote their survival and spread, the authors report.
Inflammation also supplies tumors with molecules that support diverse cancer cells, including stem cells that resist treatments and spawn additional growths. The way that tumor cells interact and colonize distant organs is an open area of investigation that could lead to new treatments, the authors suggest in the review.
Treatments should focus on cancer's complexity
The interactions of all these signals have stymied efforts to treat cancer, because sometimes fighting the disease on one front just fuels it in some other way. For example, drugs designed to starve tumors by reducing the formation of blood vessels that feed them can prompt cells within tumors to invade other sites, and medications that break down cell parts somehow protect abnormal cells instead of killing them.
Still, "there are many opportunities to develop drugs that hit cancer cells at vulnerable points," Weinberg told MyHealthNewsDaily. "What we need to deal with over the next decade is to try to understand the mechanisms whereby cancer cells acquire resistance to these drugs."
Eileen White, an oncologist at Rutgers University, said that treating cancer reminds her of the Whac-A-Mole game, in which you use a mallet to knock down plastic moles that endlessly pop up from holes in a stage. "If you combine multiple drugs that target different pathways, you have a greater chance of eliminating tumors," she said.
Johns Hopkins' Baylin agreed, emphasizing the need to strike at the central nodes where pathways converge. "The review does make us rethink how we're really going to deal with the complexity of cancer in the therapeutic approaches we use," he said.
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