Explaining Pancreatic Tumors: An Expert Q&A

Pancreatic cancer is on the rise in the United States, but there's another, less common type called pancreatic neuroendocrine tumors (PNET). It's important to know the difference, because these two cancers act differently and need different treatments.

• Pancreatic cancers start in the exocrine cells in the pancreas. This is where enzymes are made to help digest food.
• PNETs begin in endocrine (or neuroendocrine) cells in the pancreas. This is where different hormones are made, including insulin.

We spoke with Pamela Kunz, MD, FASCO, about the differences between these two cancers. Dr. Kunz is an American Society of Clinical Oncology (ASCO) expert and a medical oncologist at Yale Medicine. She specializes in the treatment of neuroendocrine tumors.

What are the key differences between pancreatic cancer and pancreatic neuroendocrine tumors (PNETs)?

Dr. Kunz: Over 90% of pancreas cancers are pancreatic adenocarcinoma. That’s the one that most of us think about when we think about pancreatic cancer. Of the other 10%, about 7% are PNETs, and the other 3% are a range of much less common cancers.

Pancreatic adenocarcinoma tends to be faster growing and is often associated with a worse prognosis (outlook). PNETs grow more slowly, patients may have had them for longer, and they may be discovered incidentally. Patients with PNET often will have years to live, even with advanced disease. The biology of these two cancers is very different, partly because they originate in different cells within the pancreas.

Who is typically most affected by pancreatic neuroendocrine tumors vs. pancreatic cancer?

Dr. Kunz: Interestingly, they will typically occur in a very similar demographic. People diagnosed with both are usually older, in their 60s and 70s. But like some other cancers, we are seeing people who are diagnosed at younger ages.

How can symptoms differ between the two diagnoses?

Dr. Kunz: The symptoms are actually very similar and are largely based on where the cancer originates in your body. If the tumor starts in the head of pancreas — that’s near the liver and the small intestines — the tumor can block something important, bringing patients to medical attention sooner. They may have a blocked bile duct, which may make their skin turn yellow, called jaundice. These symptoms can be true regardless of whether a pancreatic head tumor is from an adenocarcinoma or neuroendocrine tumor.

For patients whose cancer originates in the tail of the pancreas — on the far-left side of the body near the spleen — those may go undetected for a period of time. This is partly because there’s no opportunity for the tumor to block anything and cause symptoms. Unfortunately, many of these patients may ultimately present with disease that’s already spread outside of the pancreas. This is called metastatic disease.

How does treatment differ for pancreatic cancer vs. PNETs?

Dr. Kunz: This is where they really differ. Chemotherapy is the backbone for how we treat pancreatic adenocarcinoma. For patients with a cancer that can be surgically removed, we’ll often start with chemotherapy and may also give chemotherapy after surgery. If a pancreatic adenocarcinoma is metastatic, we use chemotherapy to help control the growth and prevent further spread.

Treatment is very different for PNETs. PNETs are categorized by terms called their “differentiation” and “grade,” both of which refer to how rapidly dividing the cancer cells are. In general, these categories serve as a dividing line for thinking about treatment for PNETs. Well-differentiated and low-grade tumors are slower growing. Whereas poorly differentiated and high-grade tumors are faster growing.

Like for pancreatic adenocarcinoma, we first determine whether the cancer can be surgically removed. If a PNET is metastatic, we use systemic treatments, including hormone-related treatments, biologic treatment, radioligand therapy, and chemotherapy. For the poorly differentiated, high-grade neuroendocrine carcinomas, we often use chemotherapy only.

If someone has been diagnosed with one of these cancers, what questions should they ask their doctor?

Dr. Kunz: Be sure you know what type you have. I’ve had patients who have done their own reading on the internet and have inadvertently gone down the wrong path. Ask your treatment doctor about your type and stage of pancreas cancer and the goals of treatment. Is the goal to cure the cancer? Or is the goal to help slow down the cancer?

Then, ask about treatment options and side effects associated with those treatments. It’s also really important to talk both about standard treatment options and clinical trials. Clinical trials are ways that we often get access to new medicines. A clinical trial may not be right for everybody. But ask your doctor, are there clinical trials available for me?

Dr. Kunz is the Editor-in-Chief of ASCO’s JCO Oncology Advances.

Note: This conversation has been edited for length.