What Is a Well Differentiated Neuroendocrine Tumor?

A well differentiated neuroendocrine tumor is a type of cancer that grows from the body’s hormone-making cells, which are scattered through organs like the gut, pancreas and lungs. “Well differentiated” is good news within that diagnosis: under the microscope the cells still look orderly, and these tumors tend to grow slowly. It is still a cancer that can spread, so it is usually treated and watched closely rather than ignored. Many people live with it for years as a long-term condition.1PubMed Central. Health-Related Quality of Life (HRQoL) in Neuroendocrine Tumors: A Systematic Review

Where These Tumors Come From and Why the Name Has Changed

Neuroendocrine cells have features of both nerve cells and the endocrine cells that make hormones.2UCSF Helen Diller Family Comprehensive Cancer Center. What Is a Well Differentiated Neuroendocrine Tumor? That is why the tumors that grow from them can sometimes release hormones into the blood, the same way the healthy cells do.3Wikipedia. Neuroendocrine tumor Because these cells exist in many organs, a tumor can start in places as different as the appendix and the lungs. It is a different disease from the common cancers of the same organ, such as typical pancreatic or bowel cancer. Under the microscope, pathologists see neat nests or ribbons of similar-looking cells with finely speckled centers, often described as “salt-and-pepper.”4IntechOpen. Histopathologic Diagnosis of Neuroendocrine Neoplasms of Head and Neck, Lung and Gastrointestinal Tract

For decades these tumors were called carcinoids, once thought of as benign or as gentler than ordinary cancers.5PubMed. Carcinoid tumors: development of our knowledge Since 2000 the World Health Organization has used “neuroendocrine tumor” instead, because “carcinoid” did not cover the full range of how these tumors behave.6PubMed. The gastroenteropancreatic neuroendocrine cell system and its tumors: the WHO classification Current classification also separates well differentiated neuroendocrine tumors from poorly differentiated neuroendocrine carcinomas, even though both carry the same cell markers.7PubMed Central. A common classification framework for neuroendocrine neoplasms: an International Agency for Research on Cancer (IARC) and World Health Organization (WHO) expert consensus proposal The older name still lingers for lung tumors and in the name “carcinoid syndrome.”8PubMed Central. Advanced typical and atypical carcinoid tumours of the lung: management recommendations

So an older letter or a different hospital may say “carcinoid” while a newer report says neuroendocrine tumor, and they usually describe the same diagnosis. Which name was used matters less than the grade and site of your tumor, so ask your doctor for both.

What the Grade and Ki-67 Number on Your Report Mean

Grade (G1, G2, G3) is set by how fast the tumor cells are dividing:

The Ki-67 index is the percentage of tumor cells caught in the act of preparing to divide, measured with a stain on your biopsy. A lower percentage means a slower-growing tumor, which makes it one of the most important numbers on your report. Some specialists now also flag tumors with a Ki-67 of 10% to 20% as behaving more aggressively than other grade 2 tumors.12PubMed. Differentiating well-differentiated neuroendocrine tumors grade 3 from poorly differentiated neuroendocrine carcinomas and adenocarcinoma with neuroendocrine differentiation: a comprehensive review

A well differentiated grade 3 tumor is not the same as a neuroendocrine carcinoma (NEC), the poorly differentiated, fast-growing kind. People with a well differentiated grade 3 tumor survive significantly longer than people with a carcinoma.13memo – Magazine of European Medical Oncology. NEC versus NET G3—is there a grey zone? Case report of pancreatic NET G3 with rapid disease progression In pancreatic tumors, median survival was about 52 months for well differentiated grade 3 versus about 10 months for poorly differentiated carcinoma.14PubMed Central. Treatment Response and Outcomes of Grade 3 Pancreatic Neuroendocrine Neoplasms Based on Morphology: Well Differentiated Versus Poorly Differentiated Carcinomas usually have even higher Ki-67 scores, grow in solid sheets rather than organized clusters, and more often show abnormal p53 and RB1 stains.15PubMed Central. Distinguishing neuroendocrine tumor grade 3 from neuroendocrine carcinoma in gastroenteropancreatic high-grade neoplasms Some grade 3 tumors with very high Ki-67 behave aggressively, so a few sit in a grey zone between the two.16memo – Magazine of European Medical Oncology. NEC versus NET G3—is there a grey zone? Case report of pancreatic NET G3 with rapid disease progression Doctors may treat those borderline tumors more like carcinomas.17PubMed. Differentiating well-differentiated neuroendocrine tumors grade 3 from poorly differentiated neuroendocrine carcinomas and adenocarcinoma with neuroendocrine differentiation: a comprehensive review

Differentiation describes how the cells look, while grade describes how fast they divide, so the two are separate measures. Asking “is mine a NET G3 or a carcinoma?” gets to the answer quickly.

When you read your pathology report, look for three things: “well differentiated,” the grade (G1, G2 or G3), and the Ki-67 percentage. If the two measures disagree, the higher one usually decides the grade. Note the primary site listed too, since the same grade can mean different things in different organs. Ask for a copy of the full report so you can show it to any specialist you see.

Where in the Body They Start and Why It Matters

In a large national registry of digestive and pancreatic neuroendocrine tumors, about 55% were classic intestinal carcinoids and about 20% were pancreatic tumors that release no hormones.18PubMed. Incidence, patterns of care and prognostic factors for outcome of gastroenteropancreatic neuroendocrine tumors (GEP-NETs): results from the National Cancer Registry of Spain (RGETNE) In about 9%, the tumor had already spread and the starting point could not be found.19PubMed. Incidence, patterns of care and prognostic factors for outcome of gastroenteropancreatic neuroendocrine tumors (GEP-NETs): results from the National Cancer Registry of Spain (RGETNE) Overall, about 44% had already spread to distant organs when first found, most often from the small intestine (65%) and least often from the appendix (about 1%).20PubMed. Incidence, patterns of care and prognostic factors for outcome of gastroenteropancreatic neuroendocrine tumors (GEP-NETs): results from the National Cancer Registry of Spain (RGETNE) So an appendix tumor found after appendix surgery usually carries a much lower chance of spread than one in the small intestine.

Site also predicts grade. Higher-grade tumors are far more likely to start in the esophagus, stomach, bowel or bile system than in the small intestine, pancreas or appendix.21The American Surgeonâ„¢. Primary Site Predicts Grade for Gastroenteropancreatic Neuroendocrine Tumors

In the lungs, low-grade tumors are called typical carcinoids and make up about 9 in 10 lung neuroendocrine tumors.22cancer.org. Lung Neuroendocrine Tumor They grow slowly, rarely spread beyond the lungs and don’t seem linked to smoking.23cancer.org. Lung Neuroendocrine Tumor Intermediate-grade atypical carcinoids grow faster, spread more often and are more common in smokers.24cancer.org. Lung Neuroendocrine Tumor Both have a more favorable outlook than high-grade lung neuroendocrine cancers.25PubMed Central. Advanced typical and atypical carcinoid tumours of the lung: management recommendations

Many of these tumors turn up by accident, during surgery or scans for something else, such as appendicitis or a colonoscopy. A small incidental appendix or rectal tumor often needs little more than removal and follow-up. Still, ask whether further scans are needed to check for spread before assuming it is fully dealt with.

Why Some Cause Flushing, Diarrhea or Low Blood Sugar and Others Cause Nothing

Functional tumors release hormones that cause symptoms, while nonfunctional tumors usually cause no symptoms at all.26PubMed Central. A review of functional pancreatic neuroendocrine tumors: Exploring the molecular pathogenesis, diagnosis and treatment About 30% to 40% of people with a well differentiated neuroendocrine tumor develop carcinoid syndrome, a set of symptoms caused by released hormones.27PubMed. Recent Advances in the Diagnosis and Management of Carcinoid Syndrome These tumors can release around 40 active substances, mainly serotonin, along with histamine and others.28Cureus. Carcinoid Syndrome: A Review From gut tumors, though, the liver normally breaks these down, so the syndrome usually appears only after the tumor has spread to the liver.29Cureus. Carcinoid Syndrome: A Review New flushing and diarrhea in someone with a gut tumor can therefore be a sign of liver spread worth reporting. Because serotonin drives most of the symptoms, its breakdown products can be measured to help diagnose and follow the syndrome.30PubMed. Serotonin pathway in carcinoid syndrome: Clinical, diagnostic, prognostic and therapeutic implications

Day to day, carcinoid syndrome often means flushing of the face and neck that comes and goes, sometimes set off by alcohol, stress or large meals. Frequent loose stools are common and may be mistaken for irritable bowel syndrome for years. Wheezing can occur, and over time some people develop heart valve problems, which is why doctors may check the heart. A symptom diary of episodes and triggers is useful to bring to appointments.

Pancreatic tumors can release specific hormones. Insulinomas cause repeated, severe low blood sugar; gastrinomas cause recurring stomach ulcers; glucagonomas cause a distinctive rash and diabetes; and VIPomas cause watery diarrhea.31PubMed Central. Clinical Characteristics and Management of Functional PanNENs: A Single Institution 20-Year Experience with 286 Patients Insulinomas are by far the most common of these.32PubMed Central. Clinical Characteristics and Management of Functional PanNENs: A Single Institution 20-Year Experience with 286 Patients Rarely, a tumor makes the hormone ACTH and causes Cushing’s syndrome, with weight gain and high cortisol.33PubMed Central. Clinical Characteristics and Management of Functional PanNENs: A Single Institution 20-Year Experience with 286 Patients

Some symptoms need a prompt call to your doctor. Shakiness, sweating or confusion that improves with sugar can mean low blood sugar from an insulinoma. Severe ongoing watery diarrhea can quickly cause dehydration. A sudden worsening of flushing with a fast heartbeat or breathing trouble needs prompt medical attention.

How Doctors Confirm It and Find Where It Has Spread

Pathologists confirm neuroendocrine tumors by staining tissue for markers such as synaptophysin and chromogranin A, which you may see named on your report.34PubMed. Comparison of INSM1 immunostaining with established neuroendocrine markers synaptophysin and chromogranin A in over 14,000 neuroendocrine and non-neuroendocrine tumors Using both together picks up about 97% of these tumors.35PubMed. Comparison of INSM1 immunostaining with established neuroendocrine markers synaptophysin and chromogranin A in over 14,000 neuroendocrine and non-neuroendocrine tumors A newer marker, INSM1, is often added and is positive in nearly all well differentiated tumors in the pancreas and lung.36PubMed. Insulinoma-associated protein 1 (INSM1) is a useful marker for pancreatic neuroendocrine tumor37PubMed. Insulinoma-associated protein 1 (INSM1) is a sensitive and highly specific marker of neuroendocrine differentiation in primary lung neoplasms: an immunohistochemical study of 345 cases, including 292 whole-tissue sections

These tumors usually carry receptors for the hormone somatostatin on their surface. A Ga-68 DOTATATE PET/CT scan uses a lightly radioactive tracer that sticks to those receptors to light up tumors anywhere in the body.38PubMed. Neuroendocrine Tumor Diagnosis and Management: (68)Ga-DOTATATE PET/CT It is done in a single day and shows tumors more sharply than the older octreotide scan.39PubMed Central. The Role of 68Ga-DOTATATE PET/CT in Well Differentiated Neuroendocrine Tumors: A Case-Based Approach Illustrates Potential Benefits and Challenges A positive DOTATATE scan also helps doctors judge whether receptor-targeted treatments may work.

For the scan, you get an injection into a vein, wait about an hour, then lie in a scanner for roughly half an hour. Your team may ask about the timing of long-acting hormone-blocking shots before the scan. Results may report an uptake number showing how strongly areas light up. Other scans like CT or MRI are often used too, especially to follow liver spots.

You may also hear about blood and urine tests. Doctors may check chromogranin A in blood as a general marker, and a urine test for 5-HIAA, a serotonin breakdown product, helps assess carcinoid syndrome. Certain foods can affect the urine test, so follow the diet instructions you are given.

Treatment Options From Surgery to Targeted Radiation

Surgery is the only treatment that can cure these tumors, even when they have spread to the liver.40PubMed Central. Treatment of Liver Metastases in Patients with Neuroendocrine Tumors: A Comprehensive Review After removal of liver spread, more than 60% of people are alive five years later, with some reports near 80%.41PubMed Central. Treatment of Liver Metastases in Patients with Neuroendocrine Tumors: A Comprehensive Review Because the disease is slow, surgeons may remove only the tumor spots and spare healthy liver to keep options open for later treatments.42Surgical Oncology Insight. Parenchymal sparing liver resection for cytoreduction of neuroendocrine tumors metastases Experts still debate some choices, such as removing the original tumor when spread can’t be cleared, or liver transplant.43PubMed Central. Surgical management of neuroendocrine tumor-associated liver metastases: a review

Somatostatin analogs (octreotide, lanreotide) are man-made versions of somatostatin, first approved to control carcinoid syndrome and later to slow tumor growth in advanced low- and intermediate-grade tumors.44PubMed. Targeting neuroendocrine tumors with octreotide and lanreotide: Key points for clinical practice from NET specialists Long-acting octreotide delays tumor growth in spread gut tumors whether or not they release hormones.45PubMed Central. Octreotide – A Review of its Use in Treating Neuroendocrine Tumours The two drugs appear to work about equally well, each holding tumors steady for about 2.5 to 3 years on average.46PubMed Central. Long-term experience with octreotide and lanreotide for the treatment of gastroenteropancreatic neuroendocrine tumors

The hormone-blocking shots are usually given every four weeks, deep into the buttock or under the skin. Common side effects include loose or fatty stools, stomach cramps, and gallstones over time. Some people learn to give lanreotide at home, and short-acting shots may be added for symptom flare-ups.

PRRT (Lutathera, Lu-177 DOTATATE) delivers radiation straight to tumors by attaching it to a molecule that seeks somatostatin receptors, the same ones the DOTATATE scan finds.47PubMed. Lutetium-177 DOTATATE: A Practical Review In a major trial it kept tumors from growing longer than octreotide alone, with manageable side effects, and earned FDA approval.48PubMed. Lutetium-177 DOTATATE: A Practical Review It is typically offered when tumors grow despite the shots, usually as about four infusions spaced around eight weeks apart. You may need to limit close contact with others, especially children, for a few days after each dose, and doctors check blood counts and kidney function because these can be affected.

For spread pancreatic tumors, the daily pill everolimus roughly doubled the time before growth, from about 4.6 to 11 months.49PubMed Central. Everolimus for Advanced Pancreatic Neuroendocrine Tumors Sunitinib is another option, and everolimus and sunitinib work about equally well in either order.50PubMed. Sequential Everolimus and Sunitinib Treatment in Pancreatic Metastatic Well-Differentiated Neuroendocrine Tumours Resistant to Prior Treatments

Not everyone starts drugs right away: slow, small tumors with no symptoms are sometimes watched with regular scans first. The order of treatments depends on grade, site, receptor status and symptoms. A specialist neuroendocrine team or tumor board helps plan treatments in sequence over years.

Outlook and Living With It Long Term

Because these tumors are often slow-growing, people may receive treatments for a decade or more.51PubMed Central. Health-Related Quality of Life (HRQoL) in Neuroendocrine Tumors: A Systematic Review In one center using PRRT, about 6 in 10 people were alive five years later, including some with higher-grade disease.52Journal of Clinical Oncology. Peptide receptor radionuclide therapy (Lu-177 PRRT) in neuroendocrine tumors (NET): Single institution experience over 15 years The outlook depends on grade, site and spread, which is why the details on your report matter so much.

The most common daily symptoms are tiredness, diarrhea, stomach discomfort and trouble sleeping.53PubMed Central. Living With Neuroendocrine Tumors: Assessment of Quality of Life Through a Mobile Application These can vary a lot from one day to the next.54PubMed Central. Living With Neuroendocrine Tumors: Assessment of Quality of Life Through a Mobile Application

Expect regular scans, often every few months at first and less often if the tumor is stable. Diarrhea from the tumor or the shots can be helped by diet changes, enzyme pills or medicine. Fatigue is real and worth raising, not just accepting. Patient groups for neuroendocrine cancer offer practical tips and specialist directories. Ask whether a specialist neuroendocrine center has reviewed your case, and what signs of growth or symptom change should prompt an earlier visit.

Could It Run in Your Family

About 10% of pancreatic neuroendocrine tumors are caused by an inherited syndrome.55PubMed Central. Inherited syndromes involving pancreatic neuroendocrine tumors The main ones are MEN1, MEN4, von Hippel-Lindau disease, neurofibromatosis type 1 and tuberous sclerosis.56PubMed Central. Inherited syndromes involving pancreatic neuroendocrine tumors Tumors that occur in these syndromes are usually the well differentiated, slow-growing kind.57PubMed. Neuroendocrine neoplasms in the context of inherited tumor syndromes: a reappraisal focused on targeted therapies MEN1 is linked with tumors in the gut, pancreas and chest.58PubMed. Neuroendocrine neoplasms in the context of inherited tumor syndromes: a reappraisal focused on targeted therapies

Most tumors carry gene changes that arose only in the tumor, not inherited, such as changes in MEN1 found in about 44% of pancreatic tumors.59PubMed Central. DAXX/ATRX, MEN1 and mTOR Pathway Genes are Frequently Altered in Pancreatic Neuroendocrine Tumors Some of these changes switch on a growth pathway that everolimus blocks.60PubMed. The landscape of molecular alterations in pancreatic and small intestinal neuroendocrine tumours A gene change on a tumor report doesn’t automatically mean your family is at risk.

It is worth asking about genetic testing if you were diagnosed young, have more than one tumor, or have relatives with hormone gland tumors. Signs of MEN1 include high calcium from overactive parathyroid glands or pituitary tumors. A blood or saliva test can check for inherited syndromes, and genetic counseling explains the results. If you carry a syndrome, relatives can be tested and screened early.