Hilary said it was rare for a 38-year-old woman to be diagnosed, and the cancer may have spread quickly without obvious signs or bumps.
Speaking to hosts Ranvir Singh and Sean Fletcher, Hilary said: “The success rate and outcomes for breast cancer have increased dramatically over the past 40 years.
“So this is very good news, we have better treatment, we have an earlier diagnosis through screening, self-monitoring, so that’s all good news,” he said.
“It’s shocking, isn’t it? At only 38 years old, ”he added.
“A lot of people say, ‘But it’s so young,’ and it is, if you look at the statistics, about 55,000 women are diagnosed with breast cancer every year, it’s the most common cancer. of all in women.
“But the majority of them will be over 50, 8,000 are under 50 and only about 2,000 are under 40, which is relatively rare.
“But all the more devastating for that, when he’s diagnosed at such a young age, and we wish him the best. ”
Sean asked if the fact that the cancer had spread meant that it had not been detected for a long time, and Hilary replied that not necessarily.
“It depends on the cell type, some cells are much more aggressive, so you can have an almost undetectable breast mass that can spread to other parts of the body,” he said.
“In other cases, the initial mass actually detected is quite large and has not spread, so a lot depends on the type of cell, the response of cells to hormones and their ability to receive other types of proteins. .
“It’s very individual, there are no general rules that you can apply to everyone.
But early detection is still the key, screening, self-checking, still very important, and I’m sure Sarah was doing all of that and sometimes it still slips through the net and it’s a tragedy when it does. . ”
* Good Morning Britain broadcast weekdays on ITV at 6 a.m.