Cancer Diagnosis Like King Charles’s Is Not Unheard-Of

A patient checks into 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 the bladder — finds a cancer.

Apparently, something like that happened to King Charles III. When the British monarch was treated for an enlarged prostate in January, doctors found a cancer that the palace said is not prostate cancer. Charles started treatment Monday. The palace did not disclose what had led to the king’s diagnosis.

While some prostate specialists like Dr. Peter Albertsen at 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 routine prostate surveillance to monitor a low-risk cancer. One of Dr. Brawley’s residents ordered a chest X-ray “for no reason,” he said. But to the surprise of Dr. Brawley, the X-ray detected a lung cancer.

Some cancers demand immediate treatment, while for others, treatment can wait, oncologists said. The palace did not describe the severity of Charles’s diagnosis, nor what treatment he was receiving.

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

“We even have a few leukemias and lymphomas where we want to start therapy less than 24 hours after suspicion,” he said. He said he doubted Charles had one of the most aggressive blood cancers, acute myeloid leukemia, nor Burkitt lymphoma. But if he did, treatment would not be put off.

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

It’s not known if the king’s cancer was found as doctors prepared for surgery, which can be preceded by something like a blood test, a CT scan or an MRI. Doctors also may detect another kind of cancer when passing a scope through a patient’s urethra during treatment of an enlarged prostate.

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

“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 a urothelial carcinoma could also show up in the prostate.

That sort 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 urological oncologist at the University of Chicago. The inner lining of the bladder has becomes cancerous and spreads through the urinary tube, he explained. The cancer can be found during the prostate treatment “when you scrape away the prostate from the inside.”

There are two types of this bladder cancer, said Dr. Judd Moul, a urological oncologist at Duke. One is “more of a nuisance condition,” he said. The cancer is scraped off surgically and medicine is put in the bladder periodically to treat any residual cells.

The other type, called muscle invasive, 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 cancer most often found during treatment for an enlarged prostate is prostate cancer. That happens about 5 percent 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 enlarged prostates.

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