Pancreas: New procedure detects tumours more efficiently (Medical Xpress, 20 August 2013)

Swiss researchers have developed a method that is able to reliably localise certain tumours in the pancreas known as insulinomas. The new method was published in the medical journal Lancet Diabetes and Endocrinology. The study has been supported by the Swiss National Science Foundation, the Swiss Cancer League and the United Kingdom's Department of Health.

Insulinomas are rare tumours that produce hormones, especially insulin. They are normally found in the pancreas and are mostly benign and small (approx. 1 to 1.5 cm in diameter). As they release insulin uncontrollably, however, leading to low blood sugar levels (hypoglycaemia), which can lead to disorientation, loss of consciousness and in rare cases to seizures or coma. They often take a long time to be diagnosed. For the patients, this means a prolonged and intensive period of suffering.

The only cure is to remove the insulinoma by a surgical intervention. However, the surgeon needs to know the exact location of the insulinoma. Using conventional imaging such as CT (Computed Tomography) and MRI (Magnetic Resonance Imaging) identifies the tumour in only 60-705 of cases. So far, invasive investigations are proposed in case of a negative outcome of conventional imaging: these include insulin concentration measurements in the vessels surrounding the pancreas.

In order to localize the insulinomas, the researchers injected an artificial substance combined with low-level radioactive indium into thirty patients with a strong suspicion of insulinomas. The substance accumulates in the tumour and, thanks to its low-level radioactive radiation, renders the mini-tumour visible in a special camera. As a result, 95% of the insulinomas could be localised. With CT or MRI, the detection rate would only have been 47%.

Dr Martin Béhé and colleagues developed the low-level radioactive substance to outwit the invisible tumour by exploiting a familiar phenomenon: nearly all insulinomas have a large number of so-called GLP-1 receptors on their surface – a kind of keyhole that can only be opened with a single key, the chemical substance GLP-1. The researchers used a similar substance they had co-developed, exendin-4, which fits the same "keyhole". Using exendin-4, the low-level radioactive indium could thus be smuggled into the tumour and its veil of camouflage lifted.

This new imaging technique will become increasingly useful for detection of insulinomas not seen using conventional imaging techniques.

Source: Medical Xpress