Pathology Lecture ◆

"Every cancer begins as a betrayal. In Margaret’s case, the betrayal started in a single crypt cell in her ascending colon. The cause? Sporadic. Bad luck. A base pair mismatch during replication. But one mutation in the APC gene—the 'gatekeeper' of the colon.

A student in the front row stops taking notes. He’s just staring.

And the macrophages believed it.

Yesterday, I signed out her case. Let’s go back to the beginning." The slide changes. A diagram of a normal colon lining—orderly, like bricks in a wall.

She clicks the remote. A photo appears: a smiling woman in her 60s, gardening. pathology lecture

She lets that word hang.

Now. Turn to page 342. We will go over the molecular pathways of colorectal cancer. But first—any questions?" "Every cancer begins as a betrayal

Now, Margaret’s tumor has a new skill: angiogenesis. It secretes VEGF, recruiting new blood vessels to feed its growth. The tumor doubles in size. It grows through the muscularis propria—the colon’s own muscle wall.

"This is Margaret’s biopsy. See the glands? They’re 'back-to-back'—no normal stroma between them. See the nuclei? They’re hyperchromatic, elongated, stratified. And here—a mitotic figure. That cell is in the middle of dividing wrong. Sporadic

"By the time Margaret felt the lump, the primary tumor was already a traitor. It had shed cells into the portal vein. Those cells traveled to the liver—the first filter. Most died there. Immune cells attacked. Shear stress tore them apart. But one cell survived. It was a stem-like cell, adaptable. It landed in the liver sinusoid and whispered to the local macrophages: ‘Don’t attack. I belong here.’