In the deserts of Arizona, a cancer-like growth fans out from the head of a saguaro cactus. It is a fasciation: a bunch of cells replicating out of control. This phenomenon produces strange mutations in plant life, but like cancer in humans, it can take a toll. While beautiful, this deformity disrupts flowering and makes the cactus more vulnerable to injury.
The Arizona Cancer Evolution Center’s garden, which it has dubbed Endless Forms Most Beautiful from a Charles Darwin quote, is full of cancerous cacti. Athena Aktipis, a professor in psychology at Arizona State University, brought them here as a reminder: we are not alone in our struggle with cancer. And someday, we might yet get better results from learning to live with it than trying to wipe it out.
While still in clinical trials, adaptive therapy has shown promise treating patients with aggressive cancers. It uses evolutionary principles to guide chemotherapy treatments and minimize drug resistance. Like the saguaro cactus, adaptive therapy aims to prolong life by managing the cancer, not eradicating it.
Aktipis studies cancer in species across the tree of life. She defines cancer as cells that cheat; they hog resources, over-proliferate, and shirk their cellular duties. From humans and whales to clams and cacti, cheating cells create cancer-like phenomena in all types of organisms. “It’s fundamental to being multicellular,” she says, “this susceptibility to cancer.”
“From the very beginning, I had this idea that cancer isn’t something I need to fight or have to try to beat. It’s a natural thing,” said Kevin Moore during an interview at the garden’s opening two years ago. He was one of the cactus garden’s designers and had stomach cancer. “Part of my body went rogue, and I had to learn to live with it,” said Moore, who ultimately passed away due to his cancer this past fall.
But many other species are better at living with cancer than people are. The saguaro cactus developed a mutation in its plant stem cells, which led to wild over-replication at its growing tip. But the cancer-like growth is limited to the end of one branch. With a little extra care, the saguaro cactus will still live a long and healthy life.
Humans, on the other hand, have stem cells embedded throughout the body. If abnormal growth is not caught early, the cancer can spread to other areas and become nearly impossible to kill. Mindy Miller, a patient advocate at the Arizona Cancer Evolution Center, has this kind of cancer.
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After working as a social worker for several decades, Miller was diagnosed with breast cancer. She had her first round of chemotherapy eight years ago, but the cancer returned and spread to her brain. Since then, she has had three craniotomies, tolerated multiple rounds of radiation, and tried a variety of medications to fight off her cancer.
“It’s just fascinating to me that these living organisms can actually survive with their cancer. They look a little funky,” says Miller, “but they have a workaround, and that’s truly my wish” — to find a more graceful way to cope with, and endure, this whole situation.
Since U.S. president Richard Nixon announced his “war on cancer” 50 years ago, treatments have largely been designed to kill as many cancer cells as possible. “This is dogma in oncology: you give a drug at maximum tolerated dose continuously until regression,” says Robert Gatenby, a cancer researcher at the Moffitt Cancer Center.
But that may not be the best way to control cancer, Gatenby says. From an evolutionary standpoint, these aggressive treatments kill off the drug-sensitive cancer cells, but often leave behind the drug-resistant ones. The leftover cancer cells then have more room to replicate and are more likely to be resistant to future treatment.
“They ultimately become cells that we just can’t control anymore,” says Gatenby, but the development of resistance is predictable. It is governed by evolutionary dynamics, which can be manipulated. Based on theoretical models, Gatenby has developed a different approach to cancer called adaptive therapy.
Adaptive therapy aims to manage cancer like the saguaro cactus does. Instead of trying to eradicate cancer cells, they are contained through strategic dosing. Patients are given just enough chemotherapy to keep the tumour small, which allows the drug-sensitive cancer cells to survive and compete with the drug-resistant cells.
This method has been tested in small groups of people with aggressive prostate cancer. Adaptive therapy gave them an average of 16 extra months with their tumours under control, while also reducing drug usage, minimizing treatment cost, and improving quality of life.
However, this approach is only practical for people with a tolerable tumour burden. Success may also vary based on the initial number of drug-resistant cancer cells. Therefore, each person’s treatment timing has to be individualized, making clinical implementation more difficult.
“If you can’t cure someone, the next best thing is to keep them on whatever their therapy is for as long as possible to delay the resistance,” says Gatenby, “and so convert cancer into a chronic disease.” He hopes that adaptive therapy will someday give people like Mindy Miller more time.
“I would love to be just a person who’s living with cancer,” says Miller, like the saguaro cactus living with its fasciation. But for now, she fights her cancer, waits for the next generation of treatments, and tends to the cactus garden — which continues to evolve.
A tree hung with shiny metallic tags now shades the cacti. Letters are engraved into each tag: the name of someone who has been impacted by cancer. When the wind blows, the tags clink against one another. A few fall to the ground. On the way to and from meetings, Miller stops to pick them up and reattach them to the branches.
The words “Kevin Moore” are on more than one. After finishing his work on the cactus garden, Moore passed away this past year from a relapse in stomach cancer. The garden remains a symbol of his hope for better ways to manage cancer.
“This is not a memorial,” says Miller. It is a reminder that cancer affects everyone — from humans and whales to clams and cacti, even those who don’t have it. She has collected remembrance tags at public events to build awareness of all the lives cancer has touched.
“Endless forms most beautiful and most wonderful have been and are being evolved,” said Darwin in “The Origin of Species.” Cancer is a part of life, says Aktipis, and all different types of organisms are developing solutions to manage their cheating cells. If we pay attention, we may find the tools we need to control ours.