King Charles’ cancer is a secret, but doctors have their own theories

We asked Professor Declan Murphy, head of genitourinary oncology at the Peter MacCallum Cancer Centre in Melbourne, which cancers are incidentally found during an operation for a benign enlargement of the prostate.

“Bladder cancer is probably the most common. It can be asymptomatic, and those with an incidentally discovered small cancer do very well on treatment,” he said.

“The first part of prostate surgery is to use a telescope to look inside the bladder. It’s not unheard of to find benign stones or a small cancer that was not detected on the pre-operation scan.

“Typically, we would remove the growth and send it for analysis. If it proves cancerous, one treatment strategy is to follow-up with a once-weekly installation of chemotherapy into the bladder over the next six weeks.”

Professor Murphy says 70 per cent of these cancers are confined to the inner lining of the bladder, and while they can be removed, they can “pop back again” and must be treated again.

“I often describe them as being more like a nuisance cancer rather than a dangerous cancer,” he said.

This cancer is common in older people, more common in men than women, and more common in smokers.

In Australia last year, 2357 men were diagnosed with bladder cancer compared with 764 women.

Although the King is not a smoker, this could chime with comments from British Prime Minister Rishi Sunak, who told the BBC that the monarch’s cancer had been caught early, and he would “crack on” with his constitutional duties

Other suggestions in the chats include the possibility of testicular lymphoma, rectal or penile cancer.

While the rectal passage is also checked during prostate surgery, and cancers have been found, Professor Murphy says this is a less likely scenario.

“At the start of prostate surgery in older men, we also inspect the external genitalia. On the penis, it is possible to uncover a small, suspicious reddened area. We would biopsy this and occasionally this could turn out to be cancer.”

Testicles are examined too, and while regular testicular cancer is more common in younger men, he said on the operating table other cancers that involve the testicle, such as lymphoma, can be found in older men.

The increasing use of magnetic resonance imaging, MRI, to detect prostate cancer has also led to increased diagnosis of incidental lesions in and around the prostate.

For a field of view of the prostate, other pelvic organs in the region are usually imaged too.

Professor Murphy says this is an unlikely scenario as the announcement suggested the cancer was diagnosed at the time of surgery.

“As Rishi Sunak said, it thankfully appears to be caught early. In our experience, this means a favourable outlook for the patient.”