Endocrine Tumors; Researchers have discovered two distinct sub types of pancreatic neuroendocrine tumors known as pNETs that have dramatically different risks of recurrence following surgical treatment [or surgery]. The finding could yield predictive tests, ease anxiety in patients whose tumors are found to be unlikely to recur, while focusing vigilant follow-up monitoring on patients with pNETs having a higher rate of recurrence.
Until now, these pancreatic neuro endocrine tumors were viewed as relatively identical from a clinical point of view. While some pNETs never develop recurrent metastases following removal of the primary tumor, other patients experience recurrence within a few years, and there has been no specific way to predict these outcomes. Physicians use tumor size as a guideline, with non-functional pNETs larger than 2 centimeters considered the most likely to metastasize following surgery.
The Endocrine Tumors
Reporting in Nature Medicine, scientists led by Ramesh Shivdasani, MD, PhD, of Dana-Farber Cancer Institute and Bradley Bernstein, MD, PhD, of Massachusetts General Hospital identified molecular information; so that may help predict the likelihood of recurrence of non-functional pancreatic neuroendocrine tumors. Non-functional pNETs do not secrete hormones and are often discovered incidentally.
The researchers used molecular analytical methods; so to describe new subtypes of pNETS that differ in the expression of specific regulatory proteins and find; so that the differences correlated with the risk of recurrence following surgical treatment. The regulatory proteins, ARX and PDX1, are epigenetic modifiers that are involve in development of the pancreas.
The scientists found that tumors whose cells exclusively express the protein ARX had more than a 35% risk of recurrence following surgery; compare to less than a 5% risk if the tumor lack ARX but express another regulatory protein, PDX1. Among study participants whose tumors show high ARX levels, cancers recurred in the liver within one to four years, compared to the rare recurrence of tumors that express PDX1.
Same hormonal system
Pancreatic neuroendocrine tumors develop from cells of the same hormonal system; so within the pancreas that controls blood sugar levels. They are relatively rare, making up only one to 2% of all pancreatic tumors. Many pNETs are benign, while some are malignant. Some pNETs secrete hormones and are termed functional; but the majority are consider non-functional.
Shivdasani and his colleagues studied molecular findings first in about a dozen pNETs; also then analyze the molecular profiles of another 142 pNET specimens. They found that about half of the pNETs express; the regulatory protein ARX and resembled normal alpha cells in the pancreas; while the other half express the PDX1 regulatory protein; also resemble normal beta pancreatic cells.
The presence or absence of those proteins was strongly correlate with outcomes: among 103 cases the researchers studied, distant metastatic relapses occur almost exclusively in patients; so whose tumors express the ARX protein but not the PDX1 protein. “This robust molecular stratification provides insight; so into cell lineage correlates of non-functional pNETs; so accurately predicts disease course; also can inform postoperative clinical decisions,” the authors wrote.
For patients whose tumors are type A, with a higher risk of recurrence; so close follow up be undertake to detect new metastases; which may be able to be treat with chemotherapy or other methods. “And even with metastatic disease,” he added, “people can live more than five years, in some cases even 10 years or longer,” he said.