Nine questions about how cancer works

How do we genuinely cure cancer — and is enough progress being made?

Are mRNA vaccines and early detection the frontier? Do whales avoid cancer because tumors compete and shrink?

Could the immune system make a self-limiting “resistant cancer” that competes with the tumor, then dies?

How is an oncolytic virus different from an mRNA cancer vaccine?

Were oncolytic agents derived from E. coli or Salmonella?

What actually makes a tumor function — mitochondria or something else?

How does ATP fit in? Could we stop it so very early cancers die?

Could light, waves, or atomic effects push ATP out of cancer cells?

Can sound force cancer to contract or shrink into itself? Does the atomic world offer a hidden lever?

What does zinc have to do with cancer?

Zinc is a mineral your body cannot do without — and its relationship with cancer is U-shaped. Too little raises risk. Far too much causes different problems. The healthy zone is the middle, and ordinary food lands you there.

Why the body needs it

Zinc is required for DNA repair and for immune surveillance — the constant patrolling that finds and removes abnormal cells. It is also built into the structure of p53, the body’s main tumor-suppressor protein, which cannot fold into its working shape without a zinc atom at its core.

Too little

Chronic zinc deficiency is linked to higher cancer risk. The clearest human evidence is esophageal cancer: regions of China and Iran where zinc deficiency is common have some of the highest rates of it in the world. In animal studies, deficiency also promotes oral cancers.

The prostate quirk

Healthy prostate tissue holds more zinc than almost any other soft tissue in the body — and prostate cancer cells characteristically lose their zinc, one of the earliest changes in that disease. It is tempting to read that as “more zinc protects.” The supplement evidence does not agree: trials have not shown protection, and in one large cohort, men who took high-dose zinc supplements — over 100 mg a day for years — developed more advanced prostate cancer, not less.

Too much

Swallowed in chronic excess, zinc blocks copper absorption, and the resulting copper shortage weakens the immune system. The U.S. tolerable upper limit is 40 mg a day from all sources — food plus supplements. The one zinc compound proven to cause cancer in humans is zinc chromate, an industrial chemical; the danger there belongs to its hexavalent chromium, not the zinc. Zinc oxide — the white stuff in sunscreen — is not classified as a carcinogen.

Get it from food

Oysters hold the most, then beef, crab, and pork; beans, chickpeas, nuts, seeds, dairy, eggs, and whole grains all carry meaningful amounts. Adults need about 11 mg a day for men and 8 mg a day for women — a normal mixed diet covers that without pills.

Has the zinc inside a penny ever been studied against cancer?

The plain answer

No — no study has ever taken zinc out of a penny and tested it against cancer. What science studies is zinc made precise in a lab: zinc oxide nanoparticles, zinc salts, and zinc ferried into cells by carrier molecules. The coin itself is a rough source. A penny minted after 1982 is 97.5% zinc under a thin copper skin; a penny from before 1982 is 95% copper, so the year on the coin decides which metal you even hold. Once zinc dissolves into ions, a cell cannot tell where it came from — but dose, purity, and delivery decide everything, and a coin controls none of the three.

How zinc attacks, in the lab

Zinc oxide particles dissolve slowly and flood a cell with zinc ions. The flood spikes reactive oxygen species, damages mitochondria and DNA, switches off the cell's anti-death proteins, and the cell dies by apoptosis — usually within about 48 hours. At the right dose, tumor cells died while healthy cells were largely spared: cancer already lives near its oxidative edge, so the flood pushes it over.

The prostate makes the deepest case. A healthy prostate hoards more zinc than almost any tissue, and that zinc blocks a fuel enzyme so the cell makes citrate instead of burning it. To become cancer, prostate cells must silence their zinc importer (a transporter called ZIP1) and dump their zinc — keeping it is incompatible with being that cancer. When researchers forced the importer back on, the cells took zinc in again and tumor growth was inhibited, even in living animals. This is the fuel machinery of Question 6, seen from the zinc side.

The hard part is delivery. Blood zinc barely enters a cell that has welded its zinc doors shut, which is why the field builds smugglers — nanoparticles, carriers, targeted packages — instead of feeding powder.

Where copper enters it

Zinc and copper are rivals at the gut door. Zinc switches on a trap protein, metallothionein, in the cells lining the intestine — and the trap grips copper even tighter than zinc. Those cells shed every few days, carrying the trapped copper out with them. This is proven medicine, not theory: zinc is an approved treatment for Wilson disease, where the body drowns in copper, prescribed precisely to bar copper at the door. It is also why overdoing zinc supplements causes copper deficiency. Push one side of the seesaw down and the other rises.

In cancer they mostly pull opposite ways: tumors tend to run copper-high and zinc-low, because copper helps build blood vessels and run growth signals. The copper-to-zinc ratio in blood has been studied as a cancer marker for exactly this reason. One honest catch: the trap protein protects whoever builds it — when a tumor cell makes metallothionein itself, the same trap can shield it, even from chemotherapy.

Copper also has a kill switch of its own. In 2022 researchers named it cuproptosis: copper smuggled into mitochondria binds the fat-tagged enzymes of the TCA cycle, they clump together, iron-sulfur proteins fall apart, and the cell dies of protein stress. Cells that breathe — burning fuel in their mitochondria rather than fermenting sugar — are far more sensitive to it. That is Questions 6 and 7 territory: the fuel machinery is where copper strikes.

The partnership

One enzyme deserves its own moment, because it is where the rivalry becomes a partnership. Cu/Zn superoxide dismutase — SOD1 — is the body's frontline cleanup for superoxide, the corrosive spark that leaks constantly from a cell's power-making. It runs in nearly every cell, all the time. Each of its molecules holds exactly one copper and one zinc. The copper does the chemistry, disarming the radical. The zinc never touches the chemistry — it is the frame, holding the protein folded into the shape that makes the copper's work possible. Neither seat can sit empty. Lose the zinc and the enzyme misfolds and clumps — the same clumping found in one inherited form of ALS. Lose the copper and the shape stands perfect and does nothing: a statue of a worker.

SOD1 is also where the seesaw stops being a metaphor. Everywhere else, zinc against copper is a balance struck across a whole body; here it is one molecule, one seat for each metal. This is the machinery underneath Question 10's curve: flood zinc and copper starves, the worker goes missing, and a healthy cell's rust defense fails; starve zinc and the frames go missing instead. Cancer researchers have aimed at this exact partnership — a copper-binding drug, ATN-224, was found to work by disabling SOD1, letting radicals rise until blood-vessel growth stalled and tumor cells died, and it reached human trials, including in recurrent prostate cancer. The enzyme that needs both metals to protect a cell is the same enzyme a tumor leans on to survive. The partnership is not a footnote to the rivalry. It is the reason the rivalry has limits.

Could copper open the zinc doors?

It is the natural next question, and the answer is no — but the no has interesting company. Copper is not the key to zinc's doors; it has a door of its own, and at the few doors the two metals share, they compete. And in prostate cancer the main zinc door, ZIP1, is not merely shut — it is switched off at the gene. Copper cannot reopen a demolished door.

What researchers use instead is a smuggler. A carrier molecule called clioquinol wraps zinc in a fat-soluble package and ferries it straight through the cell wall — no door needed. In mice carrying prostate tumors whose zinc doors were gone, clioquinol carried zinc in and slowed the tumors, matching what zinc itself does in cells whose doors still work. The copper smuggler elesclomol, from earlier in this answer, plays the same role for its metal.

And copper does set zinc free in one real place: the warehouse. Inside a cell, most zinc is not floating loose — it is parked on a storage protein, metallothionein. Copper binds that protein far more tightly than zinc does, so when copper arrives it takes zinc's seat, and the zinc is evicted — loose and active inside the cell. A copper surge can therefore raise free zinc from the cell's own stores at the same moment it attacks on its own. The limit is honest: the cell answers free zinc by building more storage protein to mop it up, and no one has yet shown the eviction frees enough zinc, for long enough, to kill a human tumor. Copper will not open zinc's doors — but it can empty zinc's warehouse, and a smuggler can bypass the doors entirely.

So a dissolved post-1982 penny would release both metals at once — and in a real stomach, the rivalry runs first: the zinc would mostly block the copper at the door. The pair arrives together and starts canceling. The honest bottom line: every mechanism above is dish-and-animal science. None of it is an approved treatment, swallowing metal is a poisoning route rather than a remedy, and the body's own answer to both metals is the same as Question 10's — the middle of the curve, held on purpose.

What are metallothionein and Cu/Zn superoxide dismutase, in plain words — and who else keeps these metals in balance?

The sponge

Metallothionein is a tiny protein covered in little sulfur hands that grab metal and hold on — a sponge whose whole job is soaking up loose metal so it cannot roll around causing trouble. It works in two places. In the lining of the gut it is the trap from Question 11: it catches copper and carries it out of the body as the gut's cells are shed. Inside every other cell it is the warehouse shelf and safety cushion: it stores zinc, hands it out when an enzyme needs some, and soaks up dangerous extras, including poison metals like cadmium. When a lot of zinc shows up, the cell builds more sponges. Because of this sponge, the amount of truly loose metal inside a healthy cell is kept at almost zero, almost all the time.

The spark-catcher

Cu/Zn superoxide dismutase — SOD1 — is a little machine that catches sparks. Making energy leaks a corrosive form of oxygen called superoxide, a spark that burns the cell from inside. SOD1 catches it and turns it into harmless exhaust, in nearly every cell, all the time. The machine is built from two metal parts. The copper is the hand that grabs the spark. The zinc is the bones that hold the machine in its working shape. Bones without a hand, and the machine stands perfect and does nothing. A hand without bones, and the machine flops and clumps — the same clumping found in one inherited form of ALS. It needs one of each, seated right, or it is not an enzyme at all.

How they work together

The sponge stores and rations the metals; the spark-catcher is one of its customers. Copper, meanwhile, is never allowed to wander a cell alone — it is too reactive. It travels hand to hand between escort proteins, and one escort exists for a single job: installing copper into SOD1. So the sponge decides how much loose metal exists, the escorts do the delivering, and the spark-catcher spends one copper and one zinc standing guard.

The rest of the crew

They are not alone. A sensor called MTF-1 is the thermostat: it tastes the loose-zinc level, and if it runs high it orders more sponges built and exit doors opened; if it runs low, more import doors. The doors themselves come in two families — ZIP doors bring zinc into cells, ZnT doors push it out or tuck it into storage bubbles. Copper has its own door, its own escorts, and two exit pumps, one in the gut and one in the liver that pushes copper out into bile; those pumps are the very ones broken in Menkes and Wilson disease. In the blood, zinc rides on a protein called albumin and copper rides on ceruloplasmin. The liver is the central bank for both metals — storing them, packaging them, and running the exits; copper's main way out of the body is bile, and zinc mostly leaves in the stool as well. One last dial: when you are ill or injured, alarm signals order zinc pulled out of the blood into the liver for safekeeping and repairs, so a blood test taken during sickness can read low even when the body's total supply is fine.

What food does to the dials

Zinc's champion food is the oyster — nothing else is close — followed by beef, crab, pork, chicken, eggs and cheese. Beans, nuts, seeds and grains carry some, but plants also carry a glue called phytate that grabs zinc in the gut and walks it out; soaking, fermenting or sprouting loosens the glue, and meat in the same meal helps plant zinc get absorbed. Copper comes easily from food: shellfish, nuts, seeds, whole grains, mushrooms, dark chocolate. The pattern that matters most is this: food almost never breaks the balance — pills do. A man needs roughly 11 milligrams of zinc and about 0.9 milligrams of copper a day, and the official zinc ceiling is 40 milligrams; a daily zinc-pill habit past that quietly starves copper through the gut trap. Alcohol drags both metals down. And some common medicines, acid blockers among them, lower mineral absorption — one more reason a supplement is a clinician's call, not a solo move.

What exercise does to the dials

A hard session makes more sparks, so the spark-catchers get used; blood levels shuffle for a few hours while zinc is pulled into liver and muscle for repairs; and a little of both metals leaves in sweat. One workout redistributes — it does not drain. The long-term effect runs the other way: regular training tells the body to build more SOD. Muscle levels of the enzyme climb within days of a session, and trained people carry more of it at rest. You cannot eat this enzyme; training is how you get more of it. The failure mode lives only at the extreme — heavy training combined with under-eating slowly drains both metals across a season, and athletes' zinc problems usually trace back to the plate, not the workout.

The plain routine

On the plate: a protein anchor at every meal; one zinc-strong food a day — beef, pork, eggs, cheese, with oysters or shellfish a couple of times a week for those who like them; a handful of nuts or seeds daily; whole grains; soak the beans. No zinc pills without a clinician; no copper pills at all — food covers copper, and excess copper is poison. In movement: walk most days for half an hour or more; do strength work two or three days a week, bodyweight counts, a little harder over time; eat a real protein meal on training days. Regular beats heroic. Put in one sentence: eat the pair from food and the ratio balances itself, move most days and your cells build more of the spark-catcher, and leave the pills to the clinic.