In 7.5 you can use EPiServer.Framework.Cache.ISynchronizedObjectInstanceCache which e.g. expose method Insert that takes a CacheEvictionPolicy as a parameter. You can pass in cacheKeys that you are dependent on to the CacheEvictionPoilcy constructor. EPiServer.DataFactoryCache have static methods to create cachekeys for content (applies to content even if some of the method names are named with Page).

Thanks, I now use:

EPiServer.CacheManager.Insert(
                    key,
                    item,
                    new CacheEvictionPolicy(
                        new List<string>() { DataFactoryCache.PageCommonCacheKey(dependencyLink) }
                    )
                );