Resistance Is a Collective Effect

01The evidence

• Tumour cells have been shown to signal to each other through paracrine loops that alter survival and growth, which is the mechanism a collective account requires.International Journal of Molecular Sciences

02The tension

Resistance is modelled as clonal selection: a rare mutant survives and expands. That predicts resistance should be rare at small tumour size and should require time proportional to mutation supply. In practice resistance can appear quickly and simultaneously across many cells, which selection struggles to explain.

03The theory

Cells under drug pressure secrete signals that alter the sensitivity of their neighbours, for instance by changing drug efflux, metabolism or cell-cycle entry. The response is a property of the population, not of a clone.

If the response is collective, it requires a quorum: below a critical density the signal is too dilute to shift phenotype, and above it the population flips into a tolerant state together. That makes resistance a density-dependent threshold rather than a waiting time.

The prediction is that resistance should appear abruptly above a density threshold, that it should be reversible when density falls, and that blocking the signal should delay it more than increasing dose.

The clinical consequence is that debulking before chemotherapy could reduce the collective response, and that dose escalation may be the wrong lever.

04What this is not

05Predictions

• P1Resistance should appear abruptly above a critical density.
• P2It should reverse when density falls, without loss of the drug.
• P3Blocking paracrine signalling should delay resistance more than dose escalation.

06What would refute it

Resistance appearing only in rare clones, independent of density, would restore selection.

07What it would change

It would change dosing strategy and make debulking a resistance-prevention measure.