Hi.. The life expectancy in a cancer is dependent on multiple factors that include the stage of the cancer, age, presence of other risk factors, other medical conditions, presence of other co morbities, presence of metastasis and so on.. And hence it is difficult to predict the expectancy.. On an average, ovarian cancer stage 4, about 17 to 20% people can survive upto 5 years... Lets hope for the best.. Our prayers and wishes to your mom..