NETs increasing but mortality stable

The annual incidence of neuroendocrine tumours (NET) in Queensland has more than trebled from 2.0 per 100,000 in 1986 to 6.3 per 100,000 in 2015.

According to retrospective study of all 4,580 cases NETs diagnosed in the state during those thirty years, rectal, stomach, appendiceal and pancreatic NETs had the greatest increase in rates.

The only primary site where decreasing rates were observed was lung NETs in males.

The overall findings – that NETs are increasing – are consistent with other studies from Europe, North America, and Asian countries.

However mortality was relatively unchanged over the study period – 0.7/100,000 in 1986 and 0.6/100,000 in 2015.

Five-year cause-specific survival improved significantly from 69.4% during 1986–1995 to 92.6% from 2006 to 2015.

Survival was highest for NETs of the appendix (96.1%) and rectum (94.5%) and lowest for unknown primary (33.2%) and pancreas (47.8%).

Male sex and older age were also risk factors for poorer survival.

The study, published in Cancer Epidemiology, said the increased incidence of NETs may be due to new and improved imaging technologies, increased use of endoscopy and colonoscopy (additional to bowel cancer screening programs), increased awareness in clinical practice, and the introduction of 2010 WHO classification for NETs.

“In the 2010 WHO classification some morphologies with “uncertain tumour behaviour status” were changed to malignant tumour status. This resulted in appendiceal carcinoid tumours previously recorded as uncertain tumour behavior, being classified as malignant,” the study said.

The researchers added that low mortality rates, despite the increased incidence of NETs, supports the hypothesis of increased detection of early stage lesions.

“While we were unable to include stage in our study, a Canadian study found the proportion of patients presenting with metastatic disease decreased by about 55% from 1995 to 2009,” they said.

They added that management advances have included improvement in surgical techniques, endoscopic management of gastrointestinal mucosal NETs, effective systemic therapies for specific subcategories of NETs (chemotherapy, sunitinib, everolimus), and Peptide Receptor Radioisotope therapy.

Another important advance has been the development of somatostatin analogues such as sandostatin. Its widespread use has previously been linked with a dramatic increase in survival rates.

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