The Exhaustion That Wasn't From Her Period

Iron-deficient blood under the microscope. The red blood cells look smaller and paler.

THE CASE

A 38-year-old woman came in exhausted. She had been that way for more than a year, getting winded on stairs she used to climb without a second thought. Her tests showed iron-deficiency anemia, and the explanation seemed obvious: her period. She was given iron, she got better, she stopped taking it, and within a few months the anemia was back. Twice. That was what didn't add up: her periods had never been heavy, and the iron was going in but not staying. One question had never been asked: where is it leaking out? The answer was in an organ you have too, one that works silently and almost never gives a warning when trouble starts.

THE INVESTIGATION

Start with a healthy colon. Its lining is made of glands that look like test tubes, side by side, all alike: they make mucus and absorb water and salts. Their nuclei are small and round, and they stay tucked at the bottom of the tube.

Healthy colon under the microscope. The glands are orderly tubes, side by side.

In a polyp, those same cells change their behavior: they look bigger, darker and crowded together, and they no longer stay at the bottom. They climb toward the surface. That has a name, adenoma: it is not cancer yet, but it can head in that direction.

A polyp under the microscope (tubular adenoma). In the center, the polyp: long, crowded glands that form a bump. On either side, healthy lining: short, even glands lined up in a row.

Why do they go off track? Because of mutations that pile up. The first one usually hits a gene called APC, whose job is to keep the "grow and divide" signal switched off. When APC breaks, that signal stays on and the cell keeps multiplying on its own. If nobody removes that little bump, other mutations can add up, and that is when cancer appears.

And here is the important part: that road is slow. Getting from a polyp to a cancer usually takes years, often more than ten.

Now, the detail almost nobody knows: a polyp doesn't hurt. And when it bleeds, it bleeds so little that you can't see it. That is why the test is called a fecal occult blood test, occult meaning hidden: it looks for what your eye can't catch. Drop by drop, that invisible loss drains away your iron. Unexplained anemia can be the first sign of something in the colon.

So why is colon cancer hitting younger and younger people? In Mexico, deaths from colorectal cancer before age 50 are rising about 2.5% a year in men. The cause is still being studied, but there is a clue: colibactin, a toxin that damages DNA. Here's the catch: not just any Escherichia coli makes it. This bacterium lives in the gut of almost all of us, but only some strains carry the machinery to produce the toxin, and not everyone has those strains. The toxin's fingerprint shows up much more often in tumors from young people, and one of its targets is APC itself.

So what does that mean for you? There is no routine test to look for this bacterium and no treatment to get rid of it, and you don't need either. What you can change is what you eat: in two studies that followed more than 130,000 people for years, a Western-style diet, heavy in red and processed meat, sugar and refined flour, was linked mainly to tumors that carried a lot of this bacterium. It seems the diet doesn't bring the bacterium in; it gives it an edge. Meanwhile, the age at which this cancer strikes is shifting: colon cancer is no longer just a disease of older people. If you are 30 or 40 and notice blood in your stool, a change in your bowel habits or anemia nobody can explain, don't brush it off because of your age: tell your doctor.

Unexplained anemia can be the first sign of something in the colon.

And the woman from the beginning? Her colonoscopy found a large polyp in the right colon, exactly where the hidden bleeding that causes this kind of anemia comes from. It was removed completely, right then and there. Under the microscope: adenoma, not cancer.

WHAT YOU CAN DO

IN SUMMARY

• When colon cells crowd together and climb upward, that is an adenoma: the step before cancer.
• The first mutation usually breaks the APC gene, and getting to cancer takes years, often more than ten. That slowness is our advantage.
• A polyp doesn't hurt, and its bleeding is almost never visible. That is why anemia can be the first warning.

That woman no longer runs out of breath on the stairs. She will need regular surveillance, but the polyp that was stealing her iron is gone. Her body had been warning her for a year in the only way it could: with iron that wouldn't stay.

Dr. Carlo De la Sancha

Pathologist, professor and researcher.

This is educational content, meant to help you understand your body. It is not a medical consultation or a diagnosis. If something worries you, talk to a doctor you trust.