From May 1, 1977, to July 31, 2009, 139 patients underwent resection of an incidentally identified PET. Thirty resections were performed from 1977 to 2000 and 109 after 2000. shows the number of patients who underwent resections per year. No sex predilection was observed in this series (51.1% women), and the median patient age was 56 years (range, 21–85 years). The indication for obtaining the axial imaging that revealed the incidental lesion was available for 71 patients (51.1%) (). The indication for imaging could not be confidently determined in the remaining patients. Tumor size ranged from 0.4 to 17.0 cm (median, 3.0 cm). One hundred tumors (71.9%) were larger than 2 cm.
Year of resection. The 2009 column includes those patients on whom operations were performed between January 31 and July 1 only.
Indication for Abdominal Imaginga
Tumors were most commonly found in the tail of the pancreas (46.8%), with 30.2% in the head or uncinate process. Seventy-four patients (53.2%) underwent distal pancreatectomy, 39 (28.1%) underwent pancreaticoduodenectomy, 17 (12.2%) underwent middle segmental pancreatic resection, and 9 (6.5%) underwent enucleation. Clear surgical margins were obtained in 121 patients (87.1%), and lymph node metastases were identified in 28 patients (20.1%). Fifteen patients (10.8%) had distant metastases at the time of initial surgery, all in the liver. Three of the patients with synchronous metastases had nonanatomic hepatic resections at the time of pancreatectomy, and 1 patient had a subsequent formal hepatectomy for a synchronous metastasis. One patient had a wedge resection of a liver metastasis before pancreatic surgery. Twenty-six patients (18.7%) had benign histologic findings, but72(51.8%) had uncertain and 39 (28.1%) had malignant findings. We were unable to confidently classify 2 tumors due to lack of information regarding mitotic rate in the pathology report. No relationship was observed between age and histopathologic findings, with median ages of 55, 56, and 57 years for patients with benign, uncertain, or malignant disease, respectively (P=.67).
No perioperative deaths were reported. Median length of stay was 7 days. One or more perioperative complications occurred in 61 patients (43.9%) (). One patient required a subsequent operation in the perioperative period for debridement of peripancreatic necrosis and abscess after a distal pancreatectomy that resulted in an uncontrolled pancreatic leak. A total of 16 patients (11.5%) patients under went postoperative chemotherapy, radiotherapy, or both.
Postoperative Complications Within 30 Days of Resection of Incidentally Identified Pancreatic Endocrine Tumorsa
Complete follow-up was available for 112 patients (80.6%), with a median follow-up of 34.2 months. Five-year and 10-year actuarial survival rates were 88.8% and 67.7%, respectively, among those with benign disease, 92.5% and 77.8%, respectively, for those with tumors of uncertain biology, and 49.8% and 16.6%, respectively, for those with malignant tumors (P=.01 overall, P=.03 for benign vs malignant, P<.001 for uncertain vs malignant, and P=.27 for benign vs uncertain). Tumor-related5-yearand10-yearmortality rates were 7.1% and 7.1% for the benign group, 6.1% and 14.0% for the uncertain group, and 35.9% and 78.6% for the malignant group. Overall survival data stratified by World Health Organization classification are depicted in and . Late metastasis, tumor recurrence, or disease progression was seen in1 patient (3.8%) with tumors initially classified as benign, 8 patients (11.1%) with tumors initially classified as uncertain, and 15 patients (38.5%) with tumors initially classified as malignant (P<.001). Negative margin status was associated with improved 5-year survival rates (91.2% vs 55.0%, P<.001), as was negative lymph node status (94.1%vs55.1%, P<.001). Among patients without positive lymph node status, no significant association was found between number of lymph nodes analyzed and survival, using a univariate Cox proportion hazards regression model (hazard ratio, 1.05; 95% confidence interval, 0.93–1.18; P=.45). Tumor size as a dichotomous variable (<2 vs ≥2 cm) was a predictor for disease progression or metastasis, with an odds ratio of 5.00 (95% confidence interval, 1.12–22.35; P=.04). However, 3 of 39 patients (7.7%) with a resected tumor no larger than 2 cm developed metastatic disease and eventually died of disease. illustrates the distribution of tumors by size.
Overall survival of patients after resection of an incidentally identified, nonfunctioning pancreatic endocrine tumor (N=139). Crosshatch marks indicate date of censure.
Figure 3 Overall survival stratified by histopathologic classification after resection of an incidentally identified, nonfunctioning pancreatic endocrine tumor. Crosshatch marks indicate date of patient censure. The difference in survival between patients with (more ...)
World Health Organization pathologic classification by tumor size. Number of tumors with each classification are shown for each size interval.
During the same period, 30 patients underwent resection for symptomatic, nonfunctioning PETs. These patients comprise 17.8% of the total group of patients with nonfunctioning PETs. When compared with the patients with incidentally discovered PETs, no difference was observed in sex (50.0% vs 48.9% men in the incidental group), median age (55 vs 56 years), frequency of malignant histopathologic findings (30.0% vs 28.1%), or surgical complications (46.7% vs 44.0%). Also, no significant difference was observed in median size of tumor (3.5 vs 3.0 cm, respectively;P=.48). Nonincidental tumors were more likely to be found in the head (36.7% vs 28.8%), but this finding did not reach statistical significance (P=.39). Five-year and 10-year overall survival rates were 81.7% and 65.4%, respectively, in the symptomatic group compared with 82.8% and 65.1% for patients with incidentally identified tumors (P=.27) ().
Overall survival from date of surgery comparing patients with incidentally identified lesions (n=139) with those with nonincidental lesions (n=30) (P=.27).