A cancer diagnosis like King Charles's is not unheard of

A patient presents to the hospital for a routine procedure to treat an enlarged prostate. And unexpectedly, a test done in the hospital—perhaps a blood test or an X-ray or an examination of the urethra and bladder—reveals that there is cancer.

Apparently something like this happened to King Charles III. When the British monarch was treated for an enlarged prostate in January, doctors discovered a form of cancer that the palace said was not prostate cancer. Charles started treatment on Monday. The palace did not reveal what led to the king's diagnosis.

While some prostate specialists, such as Dr. Peter Albertsen of the University of Connecticut, called such situations “quite rare,” other doctors said they were not unheard of.

Dr. Otis Brawley, an oncologist at Johns Hopkins Medical Center in Baltimore, said a man had come in for a routine prostate exam to monitor low-risk cancer. One of the residents of Dr. Brawley ordered a chest X-ray “for no reason,” he said. But to the surprise of Dr. Brawley discovered the x-ray lung cancer.

Some cancers require immediate treatment, while for others treatment can wait, oncologists say. The palace did not describe the severity of Charles' diagnosis or what treatment he received.

Some blood cancers are among those that need immediate treatment, said Dr. Brawley.

“We even have some leukemias and lymphomas where we want to start treatment less than 24 hours after suspicion,” he said. He said he doubted Charles had one of the most aggressive forms of blood cancer: acute myeloid leukemia or Burkett's lymphoma. But if he did, treatment could not be delayed.

Those are cancers “we're jumping on,” said Dr. Brawley. He added: “Those are things we start dealing with in the middle of the night if we have to.”

It is not known whether the king's cancer was discovered as doctors were preparing for surgery, which could be performed by, for example, a blood test, a CT scan or an MRI. Doctors may also discover another form of cancer when they insert a scope through a patient's urethra during treatment for an enlarged prostate.

Dr. Benjamin Bryer, a urologist at the University of California, San Francisco, noted that if cancer is accidentally found in a man's prostate and turns out not to have originated there, it can be a serious situation.

“It's a metastasis by definition,” said Dr. Bryer. Cancers that can spread to the prostate include melanoma, he said. A type of bladder cancer known as urothelial carcinoma can also occur in the prostate.

That type of bladder cancer is the most likely non-prostate cancer found as part of treatment for an enlarged prostate, said Dr. Scott Eggener, a urologic oncologist at the University of Chicago. The inner lining of the bladder has become cancerous and spread through the urethra, he explained. The cancer can be found during prostate treatment 'when you scrape the prostate from the inside'.

There are two types of this bladder cancer, said Dr. Judd Moul, a urologic oncologist at Duke. One is “a more bothersome condition,” he said. The cancer is surgically scraped off and medicine is periodically introduced into the bladder to treat any remaining cells.

The other type, called muscle invasive, is serious. The treatment consists of completely removing the bladder.

“Let's hope and pray that it isn't,” said Dr. Moul.

But by far the most commonly found cancer during the treatment of an enlarged prostate is prostate cancer. That happens about 5 to 10 percent of the time, Dr. estimates. Bryer, although it is study reported that prostate cancer was found in 26 percent of cases when men were treated for an enlarged prostate.

For King Charles, there is simply not enough information to guess what type of cancer he has or how it was discovered, said Drs. Bryer et al.