Tissue cultures (samples of cancer cells) are taken from cancer patients, and the cells are then grown in a laboratory. What is the purpose of growing cancer cells in a laboratory?

The anwser is to test medicinal treatments before giving them to patients.

For observation and research. This is to analyse their features, structures, physiology and other possible mutations - genetic structures that have caused it to arrive at this rate.

Cancer cells are the result of those cells that deviate from the normal life cycle of a cell. These cancer cells refuse to die and rapidly increase in number due to the uncontrollable burst of cell division.