Pancreatic Cancer
Reasoning
Pancreatic adenocarcinoma is diagnosed in just over 30,000 patients every year in the United States and has a dismal prognosis, with an almost identical yearly death rate. Surgery is the only modality that can lead to cure; however, most patients present with inoperable disease. The overall 5-year survival is <5%. Patients with localized disease have a 15% 5-year survival after curative resection. In a disease with such a poor prognosis even after curative resection, it is not only important to identify patients with resectable disease but also to spare patients with incurable disease the morbidity, inconvenience, and expense of an unnecessary operation. Thus, accurate staging of pancreatic adenocarcinoma is of paramount importance. A high quality CT scan of the pancreas is considered the best initial diagnostic modality for this disease. Nevertheless, even after appropriate preoperative imaging, 11-48% of patients are found to have unresectable disease during laparotomy. For this reason, many authors have introduced staging laparoscopy in the treatment algorithm of pancreatic adenocarcinoma patients in an effort to decrease the number of unnecessary laparotomies
Indications
- As a staging procedure for pancreatic adenocarcinoma
- For detection of imaging occult metastatic disease or unsuspected locally advanced disease in patients with resectable disease based on preoperative imaging prior to laparotomy
- For assessment prior to administration of neo-adjuvant chemoradiation
- For selection of palliative treatments in patients with locally advanced disease without evidence of metastatic disease on preoperative imaging
Contraindications
- Known metastatic disease
- Inability to tolerate pneumoperitoneum or general anesthesia
- Multiple adhesions/prior operations
Technique
The procedure is usually performed under general anesthesia, and the majority of reports have used 15 mm Hg insufflation pressures. A thorough evaluation of peritoneal surfaces is performed. The suprahepatic and infrahepatic spaces, the surface of the bowel, the lesser sac, the root of the transverse mesocolon and small bowel, the ligament of Treitz, the paracolic gutters, and pelvis are inspected with frequent bed position changes as necessary. In addition to visual inspection, peritoneal washings can be performed, ascitic fluid, if present, sent for cytology, and biopsy specimens of lesions suspected to be malignant obtained. When no metastatic disease is identified on inspection, a detailed laparoscopic ultrasound examination can be employed during which the
deep hepatic parenchyma, the portal vein, mesenteric vessels, celiac trunk, hepatic artery, the entire pancreas, and even pathologic periportal and paraaortic nodes can be evaluated and biopsied. The addition of color flow Doppler can further assist in the assessment of vascular patency. A controversy exists in the literature about the extent of staging laparoscopy for pancreatic adenocarcinoma patients. Advocates of a short duration procedure that is based only on inspection of abdominal organ surfaces argue that the procedure can be performed quickly (usually within 10–20 min), can be done through one port, does not require significant expertise, minimizes the risk of potential complications by the dissection near vascular structures, and has good diagnostic accuracy. On the other hand, advocates of a more extensive procedure that includes opening the lesser sac and assessment of the vessels argue that the diagnostic accuracy of the procedure can be enhanced by detecting metastatic lesions in the lesser sac, vascular invasion by the tumor, or deep hepatic metastasis, often missed by visual inspection alone, and that it can be performed safely without a significant increase in morbidity and within a reasonable time. It is very important, therefore, to consider these differences in technique when evaluating reports of the diagnostic yield of this procedure in patients with pancreatic adenocarcinoma.
Evidence
The feasibility of staging laparoscopy has been demonstrated in multiple studies with success rates ranging from 94-100%. Dense adhesions that impair inspection and examination with the ultrasound probe are the main reason for technical failures. Nevertheless, even patients with adhesions can be examined; however, the extent and yield of the examination may be compromised. Conversions to open surgery are uncommon and have been reported to occur in <2% of patients in a large series. The reported median (range) sensitivity, specificity, and accuracy in detecting imaging-occult, unresectable pancreatic adenocarcinoma in the literature is 94% (range, 93-100%), 88% (range, 80-100%), and 89% (range, 87-98%), respectively. However, the procedure misses 6% (range, 5-25) of patients whose disease is identified as unresectable during an ensuing laparotomy. Overall, in 4-36% of patients, an unnecessary laparotomy can be avoided. A number of studies have also evaluated the added benefit of laparoscopic ultrasound at the time of laparoscopic staging indicating that the diagnostic accuracy of the procedure can be improved by 12-14%. In addition, peritoneal washings have been reported to augment the yield of the procedure. Reports on the sensitivity of peritoneal washings have ranged widely (25-100%). The highest sensitivity for peritoneal cytology has been reported in patients with a disrupted ventral pancreatic margin (when peripancreatic fatty tissue cannot be differentiated from the tumor by helical CT scan). In addition, locally advanced pancreatic cancers have a higher incidence of positive cytology. Importantly, studies have reported a 7-14% incidence of positive peritoneal washings in the absence of other findings of metastatic disease during preoperative imaging and scopy. This incidence seems to be lower in studies that include a variety of periampullary tumors. The diagnostic yield of the procedure also depends on the histology, stage of disease, tumor size, and location. There is convincing evidence that the yield of staging laparoscopy is significantly higher in patients with pancreatic cancer compared with other types of periampullary tumors. Furthermore, staging laparoscopy appears to have a higher yield in patients with locally advanced cancer compared with patients with localized disease. Identification of metastatic disease by staging laparoscopy in patients with locally advanced disease by high quality imaging studies has been reported in 34-37% of cases, which compares favorably with the identification rates of metastatic disease in patients with localized disease. Tumors of the pancreas body and tail are associated with a higher chance for unsuspected metastasis found at laparoscopy. Larger tumors appear to be associated with a higher incidence of imaging occult metastatic disease. Although the tumor size at which the risk of occult metastatic disease justifies the added time and cost of laparoscopy is currently unknown, some studies have suggested that tumors > 3 cm are more likely to be associated with metastatic disease at exploration. Moreover, a Ca19-9 level <150 has been associated with a lower chance for metastatic disease and consequently a lower yield for staging laparoscopy.