Methods and uses relating to diagnosing ovarian cancer or determining the risk of atypical proliferative epithelial lesions or tumours progressing to invasive ovarian cancer or the risk of recurrent non-invasive disease by detecting a loss-of-function-related genetic alteration in the PAPPA gene or the absence or reduced level of functional PAPPA or an increased proportion of mitotic cells (prophase or prometaphase). Therapeutic aspects enable the sensitisation of mitotically delayed ovarian cancer cells to antiproliferative agents, preferably anti-mitotic agents, by restoring normal progression through mitosis, wherein a first therapeutic agent is applied to release ovarian cancer cells from the mitotic block and a second therapeutic agent or therapy affecting proliferating cells is administered to kill the cycling cancer cells.
