My husband has been diagnosed by a doctor that he has a mass in his stomach, could this mean cancer?

It could mean cancer, but it could also be a cyst or a symptom of IBD among other things... The best advice you could receive is to stop searching for any more info on the internet until you get a diagnosis.

As much as you don't want to hear this, there's simply no definitive answer, and you'll just end up worrying yourself about multiple different scenarios. Your best bet is to get a doctor's opinion and then take it from there.

If it's any reassurance, there are plenty of conditions other than cancer which could cause an abdominal mass though.