Neuroendocrine Tumors: The Zebra of Cancers

Sylvester Comprehensive Cancer Center’s new NET clinic tackles a rare and unusual cancer that’s difficult to detect and challenging to treat.

When most physicians hear hoof beats, they think horses, not zebras.

A flushed face is more likely to mean an overdose of niacin or a case of embarrassment than a rare cancer. Diarrhea usually suggests a gastrointestinal issue, not a genetic mutation.

Not so for doctors who treat neuroendocrine tumors (NET).

“For NET doctors, if we hear hoof beats, we think zebras first,” said Aman Chauhan, M.D., leader of the Neuroendocrine Tumor Program, co-director of the Theragnostic Program at Sylvester Comprehensive Cancer Center, and associate professor of clinical medicine at the University of Miami Miller School of Medicine.

Just as no two zebras have the same stripes, no two NET patients present identically.

“That’s why a zebra is our mascot,” Dr. Chauhan said.

“Chance” Mutations and Neuroendocrine Tumors

Though most often found in the small intestine, pancreas, lungs and rectum, neuroendocrine tumors can occur anywhere in the body. In 10% to 15% of patients, the tumors trace back to a familial genetic mutation and, in most cases, the cause of the mutation isn’t known.

“We believe this is a chance mutation, a cell making an error,” said Dr. Chauhan.

Early detection, then, is the key to better patient outcomes.

“We are definitely getting better at diagnosis,” Dr. Chauhan said. “We’re getting better at recognizing it as a disease entity.”

Doctors used to think neuroendocrine tumors were benign because they move slowly. Today, however, referrals to NET specialists and the charting of neuroendocrine tumors in registries are increasingly common.

Though still considered rare—as of 2014, an estimated 170,000 patients in the U.S. were diagnosed with NET—these tumors have increased eight-fold over the past five decades.

“In the same five decades, incidence of all major cancers has plateaued or actually mildly decreased,” said Dr. Chauhan. “We are at the cusp of not technically being a rare cancer anymore.”

Neuroendocrine Tumor Variability

Neuroendocrine tumor symptoms and trajectory can vary widely from patient to patient, as well. For some, the tumors present no symptoms. In others, the affected cells release hormones that produce flushing or diarrhea.

Some patients live for years with neuroendocrine tumors. Others see a more aggressive path. And while tumors can be identified through patient histories, physical examinations, blood tests and imaging, most community physicians don’t see neuroendocrine tumors often enough to test for them.

Dr. Chauhan encourages community oncologists to attend Neuroendocrine Tumor Society (NANETS) symposiums, seek out opinions from NET specialists and refer patients to high-volume centers.

“NET specialists would be happy to collaborate with local doctors to come up with a game plan,” he said. “If the patient qualifies for a clinical trial, then an appropriate referral can be made.”

Radiopharmaceuticals for Neuroendocrine Tumors

While surgery, chemotherapy and radiation are typically the three pillars of cancer treatment, NET is unique.

“It’s a relatively slow-growing cancer in a subset of patients,” said Dr. Chauhan. “We are trying to make radiation into the form of a medicine.”

Instead of targeting radiation on a specific tumor, physicians release a radiopharmaceutical throughout the whole body, targeting the somatostatin receptor (SSTR) on the tumor.

“Imagine a drug that latches onto the SSTR and only radiates the tumor, saving normal, bystander tissue,” said Dr. Chauhan. “We bypass a lot of radiation side effects and achieve a tremendous, anti-cancer benefit.”

Sylvester’s Neuroendocrine Tumor Program has a strong translational component.

“We do our own investigation in our labs and translate the science, and we roll it over into first-in-human studies,” said Dr. Chauhan. “Not very many places in the world do that.”

The alternative is to wait for the pharmaceutical companies, but with rare cancers, some patients don’t have the luxury of time.

 “These patients need treatment, and we have to find a treatment,” said Dr. Chauhan.

As South Florida’s only NCI-designated cancer center, Sylvester can offer access to studies targeting these treatments.

“I am honored to get support from Sylvester,” said Dr. Chauhan. “We currently have multiple trials because each sub-type of NET warrants different treatments and trials. We are spearheading some of the national and international studies and working with industry partners so our patients can have access to all these cutting-edge studies.”

So physicians, take note. When you hear hoof beats, think horses first. But think zebras second.

Tags: Dr. Aman Chauhan, neuroendocrine cancer, Neuroendocrine Tumor Program, Sylverster Comprehensive Cancer Center, USNWR Oncology