Dr Hilary Jones spoke on Good Morning Britain on Thursday about the news Girls Aloud star Sarah Harding is fighting cancer.
She revealed in an Instagram post on Wednesday that she was diagnosed with breast cancer earlier in the year, and recently discovered it had spread to other parts of her body.
Hilary said it was rare for a woman of Sarah’s age of 38 to be diagnosed, and said the cancer may have spread fast without any obvious signs or lumps.
Speaking to hosts Ranvir Singh and Sean Fletcher, Hilary said: “The success rate and the outcomes for breast cancer have increased dramatically in the last 40 years.
“So that’s really good news, we have got better treatment, we have got earlier diagnosis through screening, self-checking, so that’s all good news,” he said.
“It’s shocking isn’t it? At just 38,” he added.
“A lot of people are saying, ‘But that’s so young,’ and it is, if you look at the stats about 55,000 women are diagnosed with breast cancer every year, it’s the commonest cancer of all in women.
“But the majority of those will be over 50, 8,000 are under 50, and only about 2,000 under the age of 40, so it’s relatively uncommon.
“But all the more devastating for that, when it’s diagnosed at such a tender age, and we wish her all the very best.”
Sean asked if the fact the cancer had spread meant it went undetected for a long time, and Hilary said not necessarily.
“It depends on the type of cell, some cells are much more aggressive, so you can have an almost undetectable breast lump which can spread to other parts of the body,” he said.
“In other instances the actual initial lump that is detected is quite large, and it hasn’t spread, so a lot depends on the cell type, on whether the cells respond to hormones, and whether they have receptors for other types of proteins.
“It’s very individual, there are no general rules you can apply to everybody.
But early detection is still key, screening, self-checking, still very important, and I am sure Sarah was doing all that and sometimes it still slips through the net and it’s a tragedy when it does.”
* Good Morning Britain airs weekdays on ITV at 6am