Cancer diagnosis like King Charles’ is not unheard of

A patient is admitted to the hospital for a routine procedure to treat an enlarged prostate. And, unexpectedly, a test done in the hospital (perhaps a blood test, an X-ray, or an exam of the urethra and bladder) detects cancer.

Apparently, something like this happened to King Charles III. When the British monarch was treated for an enlarged prostate in January, doctors found a cancer that the palace says is 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 “pretty 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 check to monitor a low-risk cancer. One of Dr. Brawley’s residents ordered a chest X-ray “for no reason,” he said. But to Dr. Brawley’s surprise, the x-ray detected lung cancer.

Some cancers require immediate treatment, while for others, treatment can wait, oncologists said. The palace did not describe the severity of Charles’ diagnosis or the treatment he was receiving.

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

“We even have some leukemias and lymphomas in which we want to start treatment less than 24 hours after suspicion,” he said. He said he doubted Charles had one of the most aggressive blood cancers, acute myeloid leukemia, or Burkitt’s lymphoma. But if he did, the treatment would not be postponed.

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

It is not known if the king’s cancer was discovered while doctors were preparing for surgery, which may be preceded by something like a blood test, CT scan or MRI. Doctors can also detect another type of cancer by passing an endoscope through a patient’s urethra during treatment for an enlarged prostate.

Dr. Benjamin Breyer, a urologist at the University of California, San Francisco, said that if cancer is found incidentally in a man’s prostate and it turns out it didn’t originate there, the situation can be dire.

“It is, by definition, a metastasis,” Dr. Breyer said. Cancers that can spread to the prostate include melanomas, he said. A type of bladder cancer known as urothelial carcinoma may also appear in the prostate.

That type of bladder cancer is the most likely non-prostate cancer to be 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 is spreading through the urinary tract, he explained. Cancer can be found during prostate treatment “when the prostate is scraped from the inside.”

There are two types of this bladder cancer, said Dr. Judd Moul, a urologic oncologist at Duke. One is “more of a bothersome condition,” he said. The cancer is removed surgically, and medicine is periodically placed in the bladder to treat residual cells.

The other type, called muscle invasion, is serious. Treatment is complete removal of the bladder.

“Let’s hope and pray it’s not that,” Dr. Moul said.

But by far the most common cancer detected during treatment for an enlarged prostate is prostate cancer. That happens 5 to 10 percent of the time, Dr. Breyer estimated, although one study reported that prostate cancers were found 26 percent of the time when men were treated for an enlarged prostate.

With King Charles, there is very little information to guess what type of cancer he has or how it was discovered, Dr. Breyer and others said.