APC normally says, 'Stop dividing.' Without it, the cell becomes hyperplastic. Not cancer yet. Just... enthusiastic. A polyp. Benign. But now that cell is unstable. It divides faster than its neighbors. It acquires more mutations: KRAS (the accelerator stuck to the floor), then TP53 (the cell’s suicide switch, disabled)."
She begins to feel that vague fullness. Not pain. Just wrongness. The tumor is stiff, non-compliant. Food passing through feels like forcing a grape through a garden hose." The slide shows a cartoon of a tumor cell breaking off, entering a bloodstream, and landing on a liver.
"Margaret was a retired librarian. Non-smoker. Walked three miles a day. Six months ago, she noticed she felt full after eating only a few bites. She thought it was age. Three months ago, she noticed her stool was darker. She thought it was iron pills. Two weeks ago, she felt a lump in her right lower quadrant. She thought it was a muscle. pathology lecture
The autopsy—which I performed—showed a 4 cm liver metastasis that had replaced 60% of her liver parenchyma. The primary colon tumor had perforated silently, walled off by the omentum. And here’s what matters: we found two tiny metastases in her lungs, each 2 mm. Too small to see on CT. That’s why she didn’t respond fully to chemo—the disease was always one step ahead."
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. APC normally says, 'Stop dividing
"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.’
Setting: A darkened lecture hall, 8:00 AM. The smell of coffee and formaldehyde. Dr. Helena Voss, a pathologist in her 50s with steady hands and tired eyes, stands at a podium. On the screen behind her is a single slide: a biopsy stained pink and purple. enthusiastic
"But 'incurable' does not mean 'untreatable.' We have chemotherapy—FOLFOX or FOLFIRI. We have bevacizumab to block VEGF, stop the angiogenesis. We have immunotherapy if she’s MSI-high. Margaret was MSS—stable. So no magic bullet. But we could buy her time. Good time. Time to see her grandson’s first birthday." Part 5: The Final Chapter (The Autopsy) The last slide is a quote from William Osler: "Medicine is a science of uncertainty and an art of probability."