From reading the article it would appear that a cancer like hemangiosarcoma could indeed have a heritable component.
Research work around the impact of mapping the risk alleles in high risk breeds with a view to identifying the high risk alleles and then trying to eliminate them from the population would be great.
This information could prove to be invaluable in an ethical breeding program. I would imagine at the moment the way to deal with this is to have very good records or your breeding lines and progeny and have this disease as a specific criteria in breeding goals, not easy. To be able to asses the genetics of a dog before it is bred would be potentially invaluable.
Really it at the moment it comes down to true ethical breeding, which is breeding for the healthiest and soundest dogs using all the information that is currently available. Keeping really good records about the offspring and knowing all there is to know about your chosen breed. The show ring can sometimes derail this when certain fads come into being, it is up to ethical breeders to resist this pressure and try and makes changes to prevent this happening. Backyard breeders who just throw 2 dogs together with a view to making money are despicable as are non ethical breeders in general.