Hormone Therapy for Gastric Neuroendocrine Tumors

If you’ve been diagnosed with a gastric neuroendocrine tumor and are discussing treatment options with your cancer care team, you may have heard of hormone therapy. Your doctors may even recommend it as part of your treatment plan. While all this new information about hormone therapy can leave you feeling confused and overwhelmed, understanding how this type of treatment works is very useful. Not only will it help you stay on top of medical discussions, but it can prepare you for what to expect during your treatment journey.

Neuroendocrine tumors (NETs) are rare cancers that can occur anywhere in the body. Those that originate from neuroendocrine cells located in the mucosal lining of the stomach are called gastric NETs. These specialized cells produce hormones controlling the release of gastric juices and how quickly food moves through the stomach.

Hormones are chemical substances that help to coordinate different bodily functions, such as the growth and activity of certain cells and organs. Some gastric NETs release large amounts of hormones, such as histamine and gastrin, into your bloodstream. High levels of circulating hormones can sometimes cause symptoms like flushing and abdominal pain. Collectively, these symptoms are known as carcinoid syndrome, which occurs up to 35% of patients with NETs and is more common among those with NETs that have spread to the liver.

Hormone therapy is a type of cancer treatment that uses drugs to prevent the release of excessive hormones by the tumor cells, thereby easing the symptoms of carcinoid syndrome. These drugs also slow the growth of the tumor, although they do not typically shrink them.

Hormone therapy is used to treat gastric NETs that cannot be surgically removed (unresectable), have spread to the rest of the stomach or other organs in the body and/or are causing carcinoid syndrome. The most common locations of metastatic spread are the lymph nodes and liver.

The drugs commonly used in hormone therapy for gastric NETs are known as somatostatin analogs (SSAs). Somatostatin is a hormone that controls the release of other hormones such as gastrin, histamine and serotonin. SSAs are man-made (synthetic) versions of somatostatin that mimic the hormone’s function and can slow down the excessive production of hormones by gastric NETs. This reduces the amount of circulating hormones, thereby relieving the symptoms of carcinoid syndrome.

SSAs slow the growth of gastric NETs by inhibiting the release of gastrin, which is a known proliferative stimuli of enterochromaffin cells (ECL) that make up the gastric tumor. While this antiproliferative effect slows the tumor’s progression, SSAs unfortunately cannot cure gastric NETs completely.

Two SSAs that are used as first-line treatment for carcinoid syndrome and unresectable, metastatic gastric NETs are octreotide and lanreotide.

Octreotide

This drug is available in two forms: short-acting and long-acting octreotide. The former is given under your skin (subcutaneous), while the latter is administered as an injection into your muscle (intramuscular).

Short-acting octreotide starts working immediately but only stays in your body for a short duration. This means you will need to receive octreotide injections more frequently, roughly once or twice a day. On the other hand, long-acting octreotide is slowly absorbed, which means that the drug stays in your body for a longer period. Long-acting octreotide injections are usually administered once a month.

Depending on the severity of your symptoms and the extent of your cancer, you may receive short-acting octreotide injections every day when first beginning treatment. The long-acting injection may be used once your doctors have pinpointed the appropriate dose.

Lanreotide

Lanreotide is typically administered as a long-acting subcutaneous injection every two to four weeks. Depending on the symptoms you experience, your doctors may alter the dose and period of time between your injections.

If you are receiving lanreotide to control the growth of your gastric NET, you will continue this regimen for as long as it is working and if the side effects are manageable.

If you have any questions regarding hormone therapy and whether it can help in your treatment, please speak to your doctors and cancer care team. They may run some laboratory tests on your tumor tissue to find out if hormone therapy is suitable for you and if it is, which drug would be most effective in the treatment of your gastric NET and carcinoid syndrome.