My Sister Was Just Admitted To Hospitl Because A CT

My sister was just admitted to hospitl because a CT scan revealed a lot of fluid in stomach.Dr. drained 3 litres from her stomach. Now she has been diagnosed with cancer (not sure where) - they say there may be a mass behind belly button & she is going to be sent to another specialist in another city in the province. Is this cancer treatable and can surgery be done? It sounds serious.
Thank you-very concerned.