The Clinical Features and Molecular Mechanisms of ACTH-Secreting Pancreatic Neuroendocrine Tumors

Cui Zhang; Jiabin Jin; Jing Xie; Lei Ye; Tingwei Su; Lei Jiang; Weiwei Zhou; Yiran Jiang; Luming Wu; Ting Wang; Xu Zhong; Guang Ning; Baiyong Shen; Weiqing Wang


J Clin Endocrinol Metab. 2020;105(11) 

In This Article


Clinical Manifestations and Diagnosis (Table 1)

Of the 7 patients, 2 were males and 5 were females, ranging in age from 24 to 59 years (median age: 50 years). All patients were admitted with CS, mostly showing hypokalemia, severe fatigue, and hyperglycemia. The median course of disease was 8 (IQR 5, 10) months. All patients showed hypokalemia with serum potassium of 3.1 (IQR 2.4, 3.3). All 7 patients showed high levels of serum ACTH, serum cortisol, and 24-hour UFC. The median level of preoperative serum ACTH was 345.8 (IQR 149.2, 1112.1) pg/mL and that of UFC was 2012.6 (IQR 698.0, 18 473.0) μg/24 hours. Case 7 had the highest levels of ACTH and UFC. Six patients were diagnosed with CS by failed suppression of LDDST, and 5 of 7 patients were diagnosed with EAS by failed suppression of HDDST. Two patients (Cases 2 and 7) had extremely high levels of serum cortisol ACTH and were extremely fatigued and compulsively bedridden with pulmonary infection; they were not treated by HDDST. One could not tolerate LDDST (Case 7). All 7 patients had positive findings on CT imaging, MRI, or PET, and the primary pancreatic lesion was measured as 3.0 (IQR 2.0, 5.0) cm. Four patients had primary tumors in the uncinate process, 2 in the head, and 1 in the body of the pancreas. Two patients (Cases 5 and 7) had liver metastases at the time of diagnosis, of which 1 patient (Case 7) had additional metastases in both the adrenal gland and the retroperitoneal lymph node. One patient (Case 6) had a tumor embolus in the superior vena cava. According to the European Neuroendocrine Tumor Society staging,[19,20] 1 patient was at stage I, 2 patients were at stage IIa, 1 patient was at stage IIIa, and 3 patients were at stage IV Table 1.

Treatment (Table 1)

Case 1 and Case 3 underwent pancreatic enucleation (open and robotic, respectively) and maintained disease free status.

Case 2 underwent open pancreatic enucleation. The cortisol level declined from 44.42 μg/dL to 8.49 μg/dL, and plasma ACTH declined from 443.07 pg/mL to 89.01 pg/mL; however, the patient died of septicemia with Acinetobacter baumannii caused by pulmonary infection leading to multiple organ failure 4 weeks postoperatively.

Case 4 had a tumor in the pancreatic head involving the common hepatic artery, proper hepatic artery, and portal vein and was evaluated as borderline unresectable. Somatostatin analogs (SSAs) were given initially, and everolimus was added 1 month later as a biopsy confirmed a G2 pNET with Ki67 of 10%. Six months later, serum cortisol decreased from 18 μg/mL to 13 μg/mL, and plasma ACTH levels decreased from 301.85 pg/dL to 78.04 pg/dL. Radical surgery was attempted but ended with a right adrenalectomy. Clinical symptoms were relieved, and no infection occurred. Fourteen months later, with a relapse of serum ACTH to 295.8 pg/mL, her serum cortisol level was elevated to 60 μg/mL. An embolization of the gastroduodenal artery was performed but was complicated with pancreatitis plus an internal fistula between the duodenum and transverse colon. An emergency laparotomy was required, as a massive digestive hemorrhage persisted, and converted to pancreaticoduodenectomy with vascular resection. Postoperatively, ACTH decreased to 47.88 pg/mL, serum cortisol decreased to 0.78 μg/mL, 24-hour UFC decreased to 8.57 μg/24 hour, and the patient showed "withdrawal syndrome".[9] Venous cortisol was given to treat adrenal inefficiency. Eventually, the patient died of septicemia with Klebsiella pneumoniae and Enterococcus faecalis.

Case 5 had a large tumor in the uncinate process with multiple liver metastases. After liver TAE in another hospital, the cortisol level returned to normal, and she came to our hospital. She gave up the suggested treatment (SSA + everolimus) and was lost to follow-up. She died 1 year later according to information from a telephone interview.

Case 6 remained symptomatic after resection of the primary tumor in the uncinate process in an outside hospital. In our hospital, the tumor thrombus was found in the superior vena cava confirmed by chest CT scan with contrast and PET, and targeted therapy (everolimus) plus SSA was then recommended. Two months later, the patient died of pulmonary embolism after returning home.

Case 7 went to the emergency room for hypokalemia with a primary lesion in the pancreatic body and multiple liver metastases. She presented with severe CS with an extremely high level of serum cortisol of 200.49 μg/mL. The 68Ga DOTATATE PET/CT was negative. Distal pancreaticosplenectomy with left adrenalectomy, right partial adrenalectomy, retroperitoneal lymphadenectomy and 2 liver metastasectomies in segment III were performed. Postoperative evolution was complicated with epilepsy, hypotensive shock, fungal infection, thrombocytopenia, and chylous fistula. Methyrapone treatment was also started at day 3 postoperatively for her remaining high hormonal levels. She also showed "withdraw syndrome." She was once relieved hormonally and even transferred to an ordinary ward to prepare for subsequent TAE or capecitabine and temozolomide (CAPTEM) oral treatment. She finally died of septicemia with Klebsiella pneumoniae and Escherichia coli.

Histology and Immunohistochemistry

The immunohistochemical findings are summarized in Table 2. All pancreatic tumors were histologically confirmed as pNET after surgery (Figure 1A–C). ACTH was positive for histological staining in the pancreas of all 7 patients (Figure 1D). One patient (Case 5) had both liver and pancreas biopsy and was diagnosed with pNET and liver metastatic adenocarcinoma. One patient (Case 7) showed positive trypsin staining; for the positive staining of SYN, CgA, and neuron-specific enolase (NSE) at the same time, she was still diagnosed with pNET. According to the World Health Organization classification,[21] 3 patients had G1, 1 had G2, and 3 had G3 NETs.

Figure 1.

Immunohistochemistry staining. (A) Hematoxylin and eosin; (B) CgA; (C) Ki-67; (D) ACTH.

Survival and Prognosis

Twenty patients with ACTH-secreting TNETs were included in the control group (Table 3). The average level of preoperative serum ACTH was 342.4 (IQR 152.5, 533.4) pg/mL and that of UFC was 1140.3 (IQR 633.0, 2749.1) μg/24 hours, which were similar to ACTH-secreting pNETs (P > .05). Blood pressure, serum potassium, CA199, NSE, and tumor size were also not significantly different. The follow-up rate of patients with ACTH-secreting pNETs was 100% at the 1-year follow-up and overall follow-up. The follow-up rate of patients with ACTH-secreting TNETs was 95% at the 1-year follow-up and 85% at the overall follow-up. The 1-year survival of patients with ACTH-secreting pNETs was significantly lower than that of patients with ACTH-secreting TNETs (57% vs 90%, P < .05). During the long-term follow-up, 5 patients with ACTH-secreting pNETs and 8 patients with ACTH-secreting TNETs died (71% vs 40%, P > .05). Among the 5 deaths of patients with ACTH-secreting pNETs, 3 (G3) had metastases at the time of diagnosis (2 in the liver and 1 in the superior vena cava) and all died within the first year. Four patients without metastasis underwent surgery, 2 (G2 and G1) of whom died of surgery-related complications and ACTH-related complications, as both had the highest levels of cortisol and were infected preoperatively (1 pulmonary infection and 1 abdominal infection). The remaining 2 survivors (both G1) did not have any infections before surgery and were cured with good disease-free survival. Among the 8 deaths of patients with ACTH-secreting TNETs, 5 patients were classified as staging IV, 2 were at staging I and 1 was at staging II. Four patients had lymphatic metastasis at first diagnosis, and 2 of those patients had bone metastases during follow-up. Kaplan–Meier analysis showed that ACTH-secreting pNETs has a significantly poorer prognosis than ACTH-secreting TNETs (Figure 2, P < .05). However, Ki-67 indices in the 2 groups were similar between the 2 groups (P = 0.133).

Figure 2.

Overall survival. One-year survival rates of pNETs and TNETs were 42.9% and 89.5%. Five-year survival rates of pNETs and TNETs were 28.6% and 72.7%.

CpG POMC Promoter Methylation Analysis in pNETs and Pancreas Tissues

Four CpG sites are located in the POMC promoter upstream region, the most important of which is domain IV with E2F1 and neuroD1 binding sites. We measured the methylation rates of 5 ACTH-secreting pNETs (Cases 2, 3, 4, 6, and 7), 7 nonfunctional pNETs, and normal pancreas tissues in domain IV and found hypomethylation in ACTH-secreting pNETs compared with nf-pNET, especially in the second site (Figure 3, P < .001). Compared with normal pancreas, hypomethylation in domain IV in ACTH-secreting pNETs was significantly lower in all 4 sites (P < .05, P < .05, P < .05, P < .05, respectively). Moreover, there was also hypomethylation in the POMC promoter in ACTH-secreting TNETs compared with normal thymus.[13] However, methylation was lower in ACTH-secreting TNETs than in ACTH-secreting pNETs. The rate of methylation was not correlated with serum cortisol or tumor grade (P > .05).

Figure 3.

Methylation of domain IV in the promoter region of POMC among thymus, ACTH-secreting TNETs, ACTH-secreting pNETs, nf-pNETs and pancreas.