The growth of a cancer is dependent on several factors:

- The time it takes for a cell to duplicate itself (the
**cell cycle time**T_{c}) - The percentage of cells within the tumour that are growing (the
**growth fraction**GF) - The number of cells from the tumour that are lost, either through cell death or senescence (the
**cell loss factor**)

The **potential doubling time** *T _{pot}* of a tumour is the time it would take for a tumour to double in size, assuming that no cells are lost. It is found by:

The **volume doubling time** *VDT* is the observed time a tumour takes to double in size.

The **cell loss factor** *CLF* relates the potential doubling time to the volume doubling time, and is found by:

The CLF for many tumours is over 80-90% once they have reached a significant size.

## Factors influencing tumour kinetics

Tumours are thought to grow rapidly at first due to a low cell loss factor - the tumour is small enough that poor vascular supply and central necrosis are less of a problem. A tumour cell must undergo thirty divisions to form a clinically detectable mass.