In the diagnosis of cancer, light microscopes are used to spot tumour cells, which look different from healthy cells. In research, light microscopes are used to study changes in shape and function of cancer cells and organelles, the internal compartments within cells. They also reveal how tumours interact with surrounding cells. The new technology of light sheet microscopy has been used to study the growth over time of cancerous cells in organoids, artificially grown collections of cells which form tissues that mimic organs. Researchers have found that a single damaged cell surrounded by healthy cells is unlikely to reproduce and multiply, but a group of cancerous cells in close proximity are much more likely to form a tumour.

Super resolution microscopes show a smaller scale still, revealing f.e., that the packaging of DNA is increasingly compromised as cancer progresses.

From the earliest microscopes in the 17^th Century to the latest super resolution equipment today, light microscopes have been fundamental in both driving scientific advances and delivering benefits for wider society. They have been vital in exploring the causes of disease in order to develop objective diagnoses and effective treatments. But since Antonie van Leeuwenhoek first glimpsed bacteria through one of his homemade devices in 1676, microscopes have also fuelled amazement and wonder at nature, changing how we think of the world and our place within it.