Why is Sarcoma Tough to Diagnose?
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Sarcoma — a cancer of the bone or soft tissues including cartilage, fat, muscle or blood vessels — can be tricky to find. Not only are sarcomas rare, comprising around 1% of all cancers, but there is no way to screen for them, and a diagnosis can take months.
Every year, approximately 1.7 million Americans receive a cancer diagnosis. While breast cancer accounts for around 280,000 of those cases, sarcomas will number about 17,000 (14,000 in the soft tissue and 3,000 in the bone).
Breast cancer starts in the breast, and colon cancer in the colon. But sarcoma can start anywhere “because it starts in the connective tissue which is all over your body,” says Gina D’Amato, M.D., assistant director of clinical research at Sylvester Comprehensive Cancer Center. “There are over 170 different types of sarcoma.”
The first sign of sarcoma may be a non-painful lump or a bump on the arm or leg.
A patient may have it for a while without becoming alarmed. Even if the lump hurts, it’s common for patients to think they only pulled a muscle and not seek medical attention right away. After the patient sees a physician, it could still take six months or longer to make the diagnosis. According to Dr. D’Amato, “If we could get the word out to citizens and doctors” that anything greater than a two-centimeter lump — about the diameter of a penny — could be a sarcoma, it could make an enormous difference.
Often, physicians will think they are looking at an infection or an injury, so they’ll send the patient to a non-sarcoma specialist. In neither circumstance is the patient sent to an orthopedic/musculoskeletal oncologist or surgical oncologist with expertise in sarcoma.
But because sarcoma experts see so many sarcomas, they are more likely to spot one.
“What we see is rare, but that’s what we focus on daily,” says Francis John Hornicek Jr., M.D., director of orthopedic oncology at Sylvester and chair of the department of orthopedics at the Miller School of Medicine.
“Lack of awareness leads to a delay in diagnosis,” says Jonathan Trent, M.D., Ph.D., associate director for clinical research at Sylvester.
In some cases, he says, the diagnosis can take years, during which time the tumor spreads.
Another reason for delayed diagnoses is that not all patients come to sarcoma centers.
“We work with 20 experts,” says Dr. Trent. “We discuss every patient together, we come up with a plan for every patient.” The team focuses exclusively on sarcomas. According to a number of studies, says Dr. Trent, survival rates are better for patients who go to a sarcoma center.
Physicians, says Dr. Trent, should “have a lower threshold to do an ultrasound and a lower threshold for a biopsy if the ultrasound is concerning.” Then the biopsy should be reviewed by a sarcoma pathologist.
“When they look at it under the microscope, there is rarely 100% certainty,” says Dr. Trent. “There will be a list of other possibilities” — a differential diagnosis — “so the biopsy should be reviewed by a sarcoma specialist.”
A sarcoma pathologist changes the diagnosis around 25% of the time, says Dr. Trent.
“Everything we do afterward in terms of surgery, chemotherapy and radiation is dependent on the expert pathologist.”
There are no screening strategies for sarcomas.
With nothing corresponding to mammography or coloscopy, physicians must be trained to recognize what could be a sarcoma. And patients should be aware, too.
“If something is going on with your body that is not normal, you should tell your doctor,” says Dr. D’Amato.
Sarcoma is generally thought to be non-hereditary, she says. “But as we see more patients, we are testing tumors and seeing that there is more of a genetic component than we thought.”
Sarcoma may be associated with a mutation in several hereditary genes, such as NF-1, Rb or p53, according to Dr. D’Amato. “We are recommending that cancer patients who have family members with cancer, especially sarcoma, be referred to genetic counseling,” she says.
At present, Sylvester is running 17 phase 1, 2 and 3 clinical trials on sarcoma, including the only phase 1 trial in the southeastern U.S.
“We have some exciting new drugs,” says Dr. Trent. Sylvester researchers are testing immunotherapy and KIT inhibitors; there is a clinical trial for liposarcoma, one type of which is caused by NDM2 and CDK4 genes.
“We have brand new first-in-human inhibitors called checkpoint inhibitors,” says Dr. Trent. “We have a number of first-in-human trials.”
Miami is a good place for clinical trials because of its ethnic diversity.
“If you are doing clinical trials and only white males or white females are in the study, other ethnic groups may have different enzymes, and respond to treatments differently,” says Dr. D’Amato. “We need to have clinical trials that reflect diverse patient populations.”
The cure for sarcoma is surgery, says Dr. D’Amato, but sometimes patients aren’t diagnosed in time, or surgeons can’t remove the tumor, or there is a high risk of spread. To prevent it from coming back or at least to control it, Sylvester uses targeted therapy to interrupt the molecular abnormalities that drive cancer.
“Instead of killing cancer cells while it’s growing and dividing, we stop the signal,” says Dr. D’Amato. “There are oral and IV medications, and by doing molecular profiling on the tumor, we can potentially tailor treatments not approved for sarcoma in a clinical trial at Sylvester.” Sometimes radiation is used to shrink the tumor, but usually not when it’s reached an advanced stage. Also, some sarcomas have a limited response to radiation.
Sarcoma is one of the more common types of children’s cancer.
Adults get other kinds of cancer that children don’t. While children are no more susceptible than adults to sarcoma, according to Dr. D’Amato, “if you are a child with cancer, the chance of it being a sarcoma is higher, but as an adult, the chance that it’s a sarcoma is low.”
Sylvester treats approximately 900 new sarcoma patients a year, a large number for a relatively rare cancer.
“We have all this expertise,” says Dr. D’Amato. “Patients are coming from all over — from Florida, from other states, and other countries — because we have such a good program.”
Learn more about the sarcoma services offered at Sylvester Comprehensive Cancer Center.
Louis Greenstein is a contributing writer for UHealth’s news service.