# Log-kill hypothesis (Skipper)

Source: https://onco.cc/technologies/log-kill-hypothesis/  
OnCo record `log-kill-hypothesis` (Technology). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

A dose of chemotherapy kills a constant fraction of cancer cells, not a constant number, so each cycle removes the same proportion, which is why treatment continues after the tumour has disappeared from scans.

## Summary

Howard Skipper, Frank Schabel and colleagues showed in mouse leukaemia that a given drug dose killed a fixed fraction of cells regardless of how many were present: first-order kinetics. The corollary is that curing a cancer means driving the count from billions to zero through repeated cycles, that a single surviving cell can regrow the tumour, and that treatment must continue past clinical remission. The hypothesis shaped curative chemotherapy in childhood leukaemia and Hodgkin lymphoma and remains the framework for cycle number, though solid tumours with Gompertzian kinetics and resistant clones follow it only approximately.

## Fields

- Kind: Technology
- Status: established
- Last checked: 2026-09-17
- Tags: mathematical-model
- Principle: Cell kill per dose is a constant logarithm: surviving fraction S = exp(-k·dose) independent of the starting number, so cure requires enough cycles to pass below one cell.
- Since: 1964
- Strengths: Explains why cycles continue after remission; Basis of curative regimens in leukaemia and lymphoma; Simple and testable in models
- Limitations: Solid tumours deviate as growth fraction falls; Ignores resistant subpopulations; Assumes equal drug delivery to all cells

## Sources

- Skipper, Schabel and Wilcox 1964: https://doi.org/10.1002/1097-0142(196409)18:9<1111::AID-CNCR2820180903>3.0.CO;2-Z

## Connected records

- cancers: [Acute lymphoblastic leukaemia](https://onco.cc/cancers/all-leukemia/), [Hodgkin lymphoma](https://onco.cc/cancers/hodgkin-lymphoma/)
- fronts: [AI & Computation](https://onco.cc/fronts/ai-computation/), [Drug Discovery Platforms](https://onco.cc/fronts/drug-discovery/)
- technologies: [Cytotoxic chemotherapy](https://onco.cc/technologies/cytotoxic-chemotherapy/), [Gompertzian tumour growth](https://onco.cc/technologies/gompertzian-growth-model/)

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