"a topic of great concern" is correct and usable in written English.
You can use it to express a subject or issue that demands serious attention. Example: The health of the planet is a topic of great concern.
Availability of clean water in Europe has become a topic of great concern.
Water leaks are a topic of great concern in Britain and many other countries, because of decreasing water supplies and the deterioration of old pipework.
Due to rapid growth in urban populations, waste collection in cities has become a topic of great concern, due to it impacts on environmental pollution.
High tensile residual stresses and stress concentrations resulting from the weld process have a significant impact on fatigue life of structures, and thus a topic of great concern in product design.
Generics are getting an even bigger share of drugs spending than in richer countries (see chart).But prices are a topic of great concern in the rich world, too, especially in America, thanks to some surprising spikes in the cost of some generics.
Health risks associated with the inhalation of materials have been a topic of great concern due to highly publicized cases of inhalation anthrax, of new regulations on the release of PM2.5, and to increased concerns on the hazards of indoor air pollution.
The governor's remarks were focused on the issue of abortion--a topic of great concern to many Americans then, as it remains today.
AIDS and drug addiction is a topic of great and growing concern.
"That is a matter of great concern.
This is a matter of great concern for the state.
The discussion will open with a topic of great moment across the academic educational community, one concerning which adherents of some of the rival schools of philosophy (and philosophy of education) have had lively exchanges.
