The phrase "a significant breakthrough in" is correct and usable in written English.
It can be used when discussing an important advancement or discovery in a particular field or area of study.
Example: "The researchers announced a significant breakthrough in cancer treatment that could change the lives of millions."
Alternatives: "an important advancement in" or "a major development in".
Few participants thought there would be a significant breakthrough in the talks, set to end today.
In a significant breakthrough in one of the most mysterious murders and financial crimes, investigators say the money has been traced to offshore accounts.
Manchester United believe they have made a significant breakthrough in their world record move for Paul Pogba and hope to finalise the deal within the next 48 hours.
"The results of these UK-backed vaccine trials are hugely promising and represent a significant breakthrough in our battle against this deadly disease.
The Lithuanians' claims were brought in a civil case by the law firm Leigh Day and mark a significant breakthrough in attempts for victims of modern slavery to get justice.
The diphtheria medicine was a fairly recent discovery in 1929, and was considered a significant breakthrough in the years before the development of penicillin, said Chris Warren, 50, the academic historian at the New York Academy of Medicine.
"[The] green paper marks a significant breakthrough in that it shows that the government is willing to face up to the challenge of securing a financial settlement for future social care services.
The far-right Front National has made a significant breakthrough in the wake of the Paris terrorist attacks, winning the opening round of regional elections and coming top in half of France's regions.
VISION: New drug therapies introduced last year represent a significant breakthrough in the treatment of advanced age-related macular degeneration, the leading cause of vision loss in Americans over 60.
A significant breakthrough in climate change negotiations and national action needs to happen in order to start confronting the enormous challenges posed by global warming in 2011, although don't hold your breath waiting for this to happen.
They also spoke, however, of a "significant breakthrough" in a complex, 18-month investigation which has chased possible links with Britain, Iraq, Switzerland, Sweden, Spain and the United States.
