Researchers from the University of Iowa and the Centers for Disease Control and Prevention studied a sample of about 1,000 women in Iowa, Kansas and Missouri who had been diagnosed with ovarian cancer in 2011-2012. At the time of diagnosis, 111 had stage IV and 889 had stages I-III. The stage IV patients were more likely to be older, rural, and have other health problems.
It is tempting to attribute that difference to poverty, or difficulty in accessing health care, but the study controlled for those factors. Rural women were more likely to be diagnosed with late-stage ovarian cancer regardless of their census tract's socioeconomic status or the distance to their primary care provider.
The diagnosis-stage disparity also isn't likely related to lifestyle factors such as smoking, obesity, or lack of physical activity; though such factors are more prevalent in rural areas, they aren't prominent risk factors for ovarian cancer. And though it's possible those lifestyle factors could create a higher incidence of cancer, they aren't likely to create geographic survival or diagnostic disparities.
Rural cancer patients overall have poorer outcomes than non-rural patients, including a lower survival rate. That's true of rural ovarian cancer patients too, probably because of lower access to specialty care and treatment after diagnosis.
The researchers suggest that better access to gynecological specialists in urban areas could make a difference, since those doctors are highly trained and may be able to recognize the symptoms of ovarian cancer sooner than other health care providers.