The phrase "as a major topic" is correct and usable in written English.
You can use it when discussing a significant subject or theme within a larger context, such as an essay, report, or conversation.
Example: "In our discussion about climate change, we will focus on renewable energy sources as a major topic."
Alternatives: "as a key issue" or "as a primary focus".
Yet the war has receded as a major topic on the campaign trail, much to the relief of the Republican candidates, who never stray far from the party line but know that Americans overwhelmingly want the troops home.
Why did "scientific explanation" emerge when it did as a major topic for philosophical discussion?
MeSH annotation can be further leveraged to find which articles have a given MeSH term as a major topic to obtain articles specifically about that chemical.
In the forest monitoring corpus "remote sensing" (topics 42/87) emerged as a major topic (see Figure 7) and an area that will involve similar tasks and skills as the classification of telescopic images in the supernovae project.
Advanced channel modeling is also recognized as a major topic by two on-going research programs in Europe: the Network of Excellence in Communications NEWCOM++ and the European COST 2100 Action "Pervasive Mobile & Ambient Wireless Communications".
All types of institutions offer evolution-based courses or courses with evolution as a major topic of discussion at the introductory level, and most 4-year institutions also offer upper level evolution courses.
The proliferation of cells is a central process in biology and life, and as such a major topic in systems biology.
Education, as expected, was a major topic of discord, and distortion.
Any respondents who accessed the survey and indicated that they did not teach a course with evolution as at least a major topic were directed to an exit page.
The cost of extra funding and providing universal health care to all postdocs, not just those hired as university employees, was a major topic.
The identification of groups of vessels with the same exploitation pattern (e.g. gear used, fishing ground, target species) over time, usually referred to as a "métier", is a major topic of fishery management.
