What cancer could King Charles have? Oncologist Professor Robert Thomas weighs in

The King could be suffering from early bladder cancer, according to a health expert, following his diagnosis with 'a form of cancer' - days after he returned from hospital after receiving treatment for benign prostate enlargement. In a statement released by Buckingham Palace on Monday evening (February 5), it was confirmed that the disease, which 'is not prostate cancer', was discovered while the 75-year-old monarch was undergoing treatment at the London Clinic last week.

According to Professor Robert Thomas, who is a full-time NHS Consultant Oncologist at Addenbrooke's and Bedford Hospitals, the most likely diagnosis is early bladder cancer, which may involve the urethra - the tube which carries urine through the prostate. This form of cancer is sometimes detected during prostate treatment.

He said: "The urethra has cells similar to the bladder. Treatment would be surgical removal via a cystoscopy - although this may have been done already. If the tumour has not spread into the muscle of the urethra or bladder wall, a diluted chemotherapy is usually injected into the bladder once a week for six weeks - this causes cystitis but prognosis is usually very good - although of course we do not have all the details - this would explain why they say no duties for six weeks."

The Palace has since declined to confirm the type of cancer. However, Charles will carry on working behind the scenes on his red boxes – his state business and official papers, and returned from Sandringham to London on Monday to commence treatment as an out-patient.

He remains at home, most likely in Clarence House, his favoured residence in the capital. Buckingham Palace said in a statement earlier: “During The King’s recent hospital procedure for benign prostate enlargement, a separate issue of concern was noted. Subsequent diagnostic tests have identified a form of cancer."

“His Majesty has today commenced a schedule of regular treatments, during which time he has been advised by doctors to postpone public-facing duties. Throughout this period, His Majesty will continue to undertake State business and official paperwork as usual," the spokesperson continued.

“The King is grateful to his medical team for their swift intervention, which was made possible thanks to his recent hospital procedure. He remains wholly positive about his treatment and looks forward to returning to full public duty as soon as possible. His Majesty has chosen to share his diagnosis to prevent speculation and in the hope it may assist public understanding for all those around the world who are affected by cancer.”

What is bladder cancer?

According to the NHS, bladder cancer is where a growth of abnormal tissue, known as a tumour, develops in the bladder lining. In some cases, the tumour spreads into the bladder muscle. The most common symptom of bladder cancer is blood in urine, which is usually painless.

Once diagnosed, bladder cancer can be classified by how far it has spread. If the cancerous cells are contained inside the lining of the bladder, doctors describe it as non-muscle-invasive bladder cancer (early bladder cancer). This is the most common type of bladder cancer. 

When the cancerous cells spread beyond the lining, into the surrounding bladder muscle, it's referred to as muscle-invasive bladder cancer (or invasive bladder cancer). This is less common, but has a higher chance of spreading to other parts of the body.

If bladder cancer has spread to other parts of the body, it's known as advanced or metastatic bladder cancer.