If you were startled by the reports that 17-year-old Red Sox prospect Daniel Flores died of testicular cancer just two weeks after his diagnosis, you’re in good company.
Doctors who specialize in this type of cancer are also surprised, because testicular cancer is curable more than 90 percent of the time — even when advanced.
But they said Flores’s rapid decline and death could happen in certain circumstances.
The Red Sox said that Flores died Wednesday of complications from cancer treatment. The team has not provided further details about his medical treatment. But his trainer and close family friend told the Globe Thursday night that Flores had come to Boston Oct. 28 and was diagnosed with testicular cancer that had spread undetected to his lungs and elsewhere.
“Most testicular cancer is not as widespread or as rapidly growing as his must have been,” said Dr. A. Lindsay Frazier, an oncologist with the Dana-Farber/Boston Children’s Cancer and Blood Disorders Center, who was not involved in Flores’s care. “It’s incredibly uncommon, and incredibly sad. It certainly happens.”
Testicular cancer primarily affects men ages 15 to 35. Usually, a lump is discovered before the cancer spreads, and doctors cure it by removing the testicle.
Although Frazier said she does not know what happened to Flores, she speculated on scenarios that could have caused a rapid death from this cancer.
When it spreads, testicular cancer can get into the lungs, where it can compress a major heart artery or inhibit breathing, she said Friday. A subtype of testicular tumors sometimes fill with blood, rapidly expanding from the size of a quarter to the size of an orange. If that happens in the lungs, it can trigger respiratory failure.
This cancer also moves through the lymphatic system, which runs along the spine and near the kidneys. If tumors block outflow from kidneys, they can fail. Because kidneys eliminate drugs from the system, doctors are limited in how much chemotherapy they can provide if the kidneys aren’t working properly.
“You can’t give the full dose of chemo to patients this sick,” Frazier said.
A combination of respiratory failure and kidney failure could lead to death, she said.
“It’s a very unusual presentation of testicular cancer to be this sick right at diagnosis, but it certainly, certainly happens,” Frazier said.
Adolescents, in particular, are inclined to see doctors less often and ignore symptoms, especially when they occur in a sensitive area — such as a lump on the testicle. “I’ve seen this before — boys who presented very, very late,” she said. Even then, the cancer usually can be cured.
Dr. Adam S. Kibel, chief of the Division of Urology at Brigham and Women’s Hospital, said Friday that in his 20 years of practice, he has never seen a testicular cancer case progress so rapidly. Even patients who eventually succumb, he said, usually first undergo rounds of treatment that keep the cancer at bay.
“This is a highly unusual sequence of events,” said Kibel, who also had no involvement in Flores’s care. “It’s likely either a very rare tumor or a very rare event associated with the common tumor.”
Dr. Paul Mathew, a genitourinary oncologist at Tufts Medical Center, said that on rare occasions he has seen young men with testicular cancer die quickly when treatment complications interact with advanced disease.
“There may have been treatment-related complications that got worse,” Mathew said. If the cancer had spread to his lungs or brain, there could have been fatal bleeding, for example.
Flores underwent extensive physical exams in July, according to José Salas Jr., who was serving as his trainer in their native Venezuela and had become his surrogate father. Salas said he did not know of any complications and that Flores’s death puzzled doctors.
But, Mathew said, sometimes a small tumor that isn’t detected can still spread cancer elsewhere in the body. And athletes like Flores may attribute aches and pains to their training, dismissing symptoms of an advancing cancer, he said.
Salas, the friend and trainer, told the Globe that Flores had complained of back pain but insisted “it’s OK,” attributing the pain to a pulled muscle or “just a bad night.”
Massachusetts General Hospital, where Flores was treated, declined to answer questions about his case, citing privacy concerns.
Salas said Flores’s family has not sought an autopsy.
“We are at peace,” Salas said Friday. He praised the doctors at Mass. General for their efforts to help the young player.
“Daniel is an angel who was taken by God,” Salas said. “It was his time.”
The typical course of testicular cancer is much different from what Flores underwent. If the cancer is confined to the testicle, removing it is often the only treatment needed, with a 99 percent survival rate.
If the cancer has spread, the patient is treated with chemotherapy or surgery, and on rare occasions, radiation.
The five-year survival rate is 96 percent when testicular cancer has spread to nearby tissues and 73 percent when it has spread more distantly, according to the American Cancer Society.
The society estimates that this year there will be 8,850 cases of testicular cancer, leading to 410 deaths.
Kibel, of the Brigham, recommends that boys and young men check their testicles for lumps once a month.
Dana-Farber’s Frazier said, “I don’t want boys to worry, but it is a wake-up call. They should tell somebody if they see something changing in their body.”Maria Cramer of the Globe staff contributed to this report. Felice J. Freyer can be reached at email@example.com.