This has never been the view of menopause specialists and thankfully the guidelines for non-specialists have now been updated so nobody should be asked to stop hormone therapy whilst waiting for a scan.
Someone posted a link to the updated guidelines on this forum within the past week.
Endometrial cancer develops over years, not weeks, and as the evidence shows that women on combined HRT are actually at LOWER risk of endometrial cancer than those on no treatment, the level of panic and over investigation of every woman on hormone therapy with a bit of spotting is frankly irresponsible and a poor use of resources in my opinion.
It is actually one of the reasons clinicians are reluctant to prescribe hormone therapy, because of every innocent bleed, which is often a result of an atrophic rather than hyperplastic endometrium, having to be referred along the 2 week wait pathway as if it were suspected cancer.
It also clogs up the system for people with actual cancer.
Anyway I am not trying to discourage anyone from getting investigated, just that in my opinion treating this as potential cancer in the absence of any clinical red flags is inappropriate, and certainly nobody needs to stop treatment whilst waiting.