The Science Is In: Exercise During Cancer Treatment Isn't Just Safe—It's Essential

"Better than a drug" - Dr Julie Gralow, the chief medical officer of ASCO

For seventeen years, Jessica and I have been throwing medicine balls at each other's faces. Not in anger—in friendship. Three times a week, we meet in someone's garage gym to lift, jump, squat, and generally torture ourselves in the name of fitness. It's been our constant through pregnancies, job changes, teenagers, and yes, cancer.

When I was diagnosed with triple-negative breast cancer in January 2023, I worried this ritual might end. Would chemo make me too weak? Too tired? Too fragile for our beloved barbarism?

Instead, it became my lifeline.

The Research That Changes Everything

Emerging research is now confirming what my body knew intuitively: exercise isn't just safe during cancer treatment—it's medicine. The American College of Sports Medicine shows "Exercise Is Medicine," and recent studies suggest that a drug with similar benefits would likely be prescribed widely.

• Exercise is medicine in oncology: Engaging clinicians to help patients move through cancer

• Exercise as cancer treatment: A clinical oncology framework for exercise oncology research

• Exercise, Diet, and Weight Management During Cancer Treatment: ASCO Guideline

• Impact of exercise on cancer: mechanistic perspectives and new insights

• The expanding role of exercise oncology in cancer care: An editorial highlighting emerging research

• Exercise as cancer treatment: A clinical oncology framework for exercise oncology research

When I Refused to Be "Fragile"

Throughout twelve weeks of carboplatin and Taxol, I lifted weights with Jessica Monday, Wednesday, and Friday. I walked or cycled on the other days. My oncologist was thrilled—my labs looked like those of someone not even on chemotherapy. Research now confirms that exercise can reduce tumor growth, mitigate treatment side effects, and enhance survival rates—benefits so significant that scientists are calling for exercise to be integrated as a standard part of cancer care. (see: Frontiers | Impact of exercise on cancer: mechanistic perspectives and new insights)

But here's what the studies don't capture: the psychological power of throwing a medicine ball at your best friend while poison drips through your veins. Each workout was defiance. Each bead of sweat was proof that cancer hadn't won.

Irit's Revelation

Irit, a 34-year-old program manager at BC Women's Hospital, discovered this truth through her Peloton. Diagnosed with Stage 3 estrogen-positive breast cancer while juggling two toddlers, she made exercise her rebellion. "Exercise isn't just movement; it's my rebellion against cancer," she told me.

Her Sunday ritual? A steak dinner before Monday's bloodwork—nothing was postponing her battle. Through eight rounds of chemotherapy, she pedaled through fatigue, finding solace in movement. When hyperbaric treatments for cellulitis threatened to derail her routine, she transformed even those sessions into bastions of resilience.

The Science Behind Our Stubbornness

The latest ASCO guidelines now recommend regular aerobic and resistance exercise during active treatment with curative intent Exercise, Diet, and Weight Management During Cancer Treatment: ASCO Guideline | Journal of Clinical Oncology—a dramatic shift from the old "rest and recover" mentality. New research indicates that exercise and nutrition interventions can enhance the maintenance of lean body mass, reduce adverse events, and decrease hospital stays. Exercise and Nutrition to Improve Cancer Treatment-Related Outcomes (ENICTO) | JNCI: Journal of the National Cancer Institute | Oxford Academic

The mechanisms are fascinating: Exercise boosts immune function, reduces inflammation, and may even make chemotherapy more effective by improving blood flow to tumors. Scientists are now studying exercise as an actual cancer treatment across nine distinct clinical scenarios, not just supportive care, but active therapy.

Why Your Oncologist Should Be Your Gym Buddy

Yet here's the maddening part: Despite recognition of exercise benefits, many healthcare providers remain skeptical about integrating exercise into patient care, creating a disconnect between research and practice. Implementation barriers to integrating exercise as medicine in oncology: an ecological scoping review | Journal of Cancer Survivorship. Too many patients are still told to "take it easy" when they should be lacing up their sneakers.

Irit's advice resonates: "It's a mental game. My motto is to keep going; tomorrow isn't guaranteed for anyone." Exercise became her routine, her anchor, her proof that she was still living, not just surviving.

The Double Happiness Tripwire

For Jessica and me, those garage gym sessions became sacred. Between sets, we'd laugh about our kids, complain about our husbands, and dream about our futures. The combination of friendship and exercise created what I call a "double happiness tripwire", two sources of joy reinforcing each other.

Cancer tried to steal my life. Instead, it gave me clarity about what mattered: not just the medicine balls we threw, but the hands that caught them.

The research is finally catching up to what warriors like Irit and I have known all along: Exercise doesn't just help you survive cancer—it helps you thrive through it and recover faster. So, ask your oncologist not just about your treatment plan, but also about your workout plan.

After all, if you're going to fight for your life, you are strong enough to win.