9 All cancers evolve along the same trajectory
Cancer is a triad manifested by:
1. Tumor (T)
2. Paraneoplasia (Neuro-hormonal changes) (P)
3. Cachexia (progressive weight loss and wasting) (C)
Cancer progression involves all three. Paraneoplasia and weight loss may even precede tumor appearance.
Mathematically cancer is a triplet, consisting of three components {T,P,C}. It is a three dimensional vector. Al cancers evolve along the same trajectory. The polyp-cancer sequence is a prototype of a typical neoplastic trajectory. The polyp-cancer sequence serves here as a prototype of neoplastic progression of all tumors. They all proceed through states analogous to the polyp cancer sequence.
Since cells stream to their graveyards, they do not de-differentiate. Neither does the tumor. What appears as tumor de-differentiation results from an ongoing accumulation of younger and younger cells due to their arrested maturation. With time tumor becomes younger and proliferates faster.
Trajectories of the following cancers are depicted: Colon, breast, CML
Maturation arrest is the main reason why cancer is generally incurable. The other two are para-neoplasia and cachexia, which defy any treatment.