- As a treatment algorithm considering risk factors of relapse and clinical pathological features,

- It is helpful in selecting a target patient who needs surgical treatments and estimate the scope of surgery.

We have got a research result suggesting a treatment algorithm by analyzing risk factors of recurring pancreatic neuroendocrine tumors. It will be helpful in selecting a patient who needs surgical treatments and estimate the scope of surgery, considering the prognostic factors and clinical pathological features based on the size of the pancreatic neuroendocrine tumors.

Dr.Wooil Kwon and his team including Dr. Jinyoung Jang and Dr.Hongbeom Kim at Hepatobiliary and Pancreatic Surgery, Seoul National University Hospital studied the data from a large cohort of 918 patients, who underwent the treatments for pancreatic neuroendocrine tumors between 2000 and 2017. At the study, they analyzed the risk factors fro recurring tumors and opened the result to the public on the 28th, suggesting a treatment algorithm.

pancreatic neuroendocrine tumor, which Steve Jobs suffered from, is basically different from a pancreatic cancer. While pancreatic ductal adenocarcinoma occurs from the cells in the pancreatic duct, pancreatic neuroendocrine tumors occur in the endocrine cells of the pancreas, of which the incidence rate is lower than that of pancreatic cancer. Tes, recently the incidence rate of pancreatic neuroendocrine tumors is increasing thanks to the advanced imaging technology and patients'active early health check-ups.

Unfortunately, it is tricky to decide if a patient needs a surgical treatment and to determine the surgery scope since its characteristics vary from benign to malignant. The prognostic factors are also unclear and the current treatment guidelines are too simple with a certain limitation.

In particular, the prognostic values are not only inconsistent but also not fully verified. That said, the result of this study has significant implications for understanding pancreatic endocrine tumors.

Acorrding to the study. the 5-year survival rate without having a relapse was 86.5% after the patient underwent the surgery for pancreatic neurocrine tumors.

It is reported that the risk factors are ▲remaining tumor cells on the resection surface after surgery, ▲the grade classified high in the World Health Organization(WHO), and ▲lymph node metastasis.

While it is hard to say that the size of tumor can be a direct risk factor to cause relapse, we could confirm that it indirectly affects recurrence when clinical pathological characteristics are reflected.

When compared to tumors larger than 2cm, tumors less than 2cm belong to a lower grade of WHO tumor classification, have less metastasis to lymph node, and show much better survival rate as long as 5 years without relapse. For smaller tumors sized between 1 and 2cm, the metastasis rate to lymph node was 10.3%, and recurrence occurred at 3%. Tumors less than 1cm have hardly had the metastasis to lymph node or recurrence.

So far, most studies have recommended observing the progress of tumors less than 2cm. However, we have found that even tumors sized 1 to 2cm have 10 % rate of metastasis to lymph node and 20% of them are identified as high in the WHO tumor classification, showing that its malignancy cannot be ignored.

Our team has recommended observing tumors less than 1cm can be appropriate but tumors 1 to 2 cm require surgical procedures.

<Figure> Treatment algorithm reflecting prognostic factors and clinical pathological features depending on the size of tumors

Dr.Wooil Kwon said, " While previous studies were conducted with statistical database, our research utilized a large-scale cohort study reflecting clinical data collected from 14 major domestic university hospital and the Korean Pancreatic Surgery Research Association, which helps our research carry more accuracy and reliability."

He also added, "Following our study, it is valid to determine a treatment procedure based on the size of tumors even though the size itself cannot be an independent risk factor for relapse. In the future, it will be an important milestone to predict 1 to 2cm high-risk tumors." This research result was published in "Neuroendocrinology," the European Journal of Neuroendocrine Oncology, which has the highest public confidentce in the field of neuroendocrine tumors.