The Price of Construction: Cancer, entropy, and the cost of carrying convention

Cancer is not an outside packet entering a host. It is the cost of construction paid from inside the self. A multicellular body persists by copying, repairing, replacing, and policing its own cells. That construction carries a convention through time: what counts as self, what belongs to the body, what should divide, what should stop, what should repair, and what should be cleared.
But construction runs under entropy. DNA is chemically unstable, replication is high-fidelity but not perfect, repair is powerful but not free, and every lineage of cells accumulates change over time. Most drift is repaired, harmless, or dead. Some drift remains constructable. A smaller subset can replicate, evade suppression, and become a competing lineage inside the body that built it.
This paper treats cancer as the endogenous form of the Cost-of-Surprise loop. In phage-CRISPR immunity, the threat arrives from outside; in cancer, the threat begins as self. That difference makes the recognition problem harder, not weaker. The immune system is not sorting foreign from self, but self from self-gone-wrong. Somatic mutation supplies novelty. Immune surveillance and immunoediting supply recognition pressure. Tumor evolution selects the variants that remain viable while escaping control.
The claim is not that cancer has purpose, strategy, or intention. The claim is that construction has a price: copying the self over time produces drift, and some drift remains alive enough to answer back.