4.1.3.5. Results of computed tomography and magnetic resonance imaging.
Computed tomography, especially multi-slice computed tomography and magnetic resonance imaging, is a diagnostic method with higher accuracy than abdominal ultrasound, assessing the degree of vascular invasion to decide whether to resect the pancreaticoduodenectomy or not [51]. Direct signs are images of the tumor, comparing the density of the tumor before and after contrast injection [116]. Small tumors (usually < 2 cm) are difficult to detect by computed tomography, only indirect signs such as dilatation of the intrahepatic and extrahepatic bile ducts and dilatation of the main pancreatic duct can be seen. Multi-slice computed tomography has a sensitivity and specificity ranging from 75 - 100% and 70 - 100%, respectively. However, when the tumor is < 2 cm in size, computed tomography has a sensitivity of 68% - 77%, when the tumor is > 2 cm, the sensitivity increases to 98% [117].
Computed tomography and magnetic resonance imaging also have prognostic value in the possibility of pancreaticoduodenal resection and are significant in selecting patients for laparoscopic surgery. The following images are considered warning signs of unresectable tumors: liver metastasis; tumor invasion of the superior mesenteric vein and portal vein; tumor invasion of the superior mesenteric artery with signs such as loss of fatty rim around the vessel, tumor invasion causing deformation, stenosis or occlusion; collateral circulation in the post-pancreatic region, splenic hilum and enlarged spleen; peritoneal metastasis [51].
Currently, with good techniques, combining chemotherapy and radiotherapy before and after surgery, tumors at the border between resectable and non-resectable tumors are still indicated for pancreaticoduodenectomy such as: (i) pancreatic head tumors invade the hepatic artery but have not invaded the celiac artery, (ii) tumors adhere to the superior mesenteric artery less than 180 0 around the circumference, (iii) invasive tumors cause obstruction of the portal vein, superior mesenteric vein or a short confluence but above and below the common vein enough to cut or graft the vessel. These characteristics can be completely assessed on computed tomography before surgery [118].
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Magnetic resonance imaging (1.5 Tesla or higher) can image the biliary and pancreatic ducts, vascular invasion, and can even detect
Endocrine pancreatic tumors, even very small ones, are an adjunct to computed tomography in diagnosis [38], [119].
In our study, 21 patients underwent CT scans and 12 patients underwent MRI scans with tumor detection rates of 85.7% and 91.7%, respectively, and no cases of vascular invasion or pancreatic duct dilation were found in 28.6% and 75%, respectively (Tables 3.8 and 3.9). Of the 21 patients undergoing CT scans, 3 patients (Nos. 14, 22, and 27) underwent additional MRI and endoscopic ultrasound. Patients No. 14 and 22 did not have tumor lesions detected on CT scans but had tumors detected on MRI and endoscopic ultrasound. Patient No. 27 had tumors detected on all CT scans, but the CT scan was taken at a lower level, so additional MRI and endoscopic ultrasound were indicated to confirm the diagnosis and assess the degree of invasion before surgery.
4.1.3.6. Gastroscopy results
Flexible gastroduodenoscopy allows the endoscopist to directly observe the local lesions of the ampulla of Vater, biopsy suspicious lesions for histopathological diagnosis before surgery. Through endoscopy, it is easy to detect tumors located in the ampulla of Vater (vesiculated lesions, ulcers, bleeding) or duodenal tumors (loss of mucosal folds, hard infiltration, etc.), but it is very difficult to detect tumors in the common bile duct or pancreatic tumors. We indicated flexible upper gastrointestinal endoscopy for all 30 patients (Table 3.10). Vater ampulla tumors were detected in 23 cases (76.7%), tumor lesions infiltrated into the duodenal wall in 1 case (3.3%), external masses compressing the duodenum (3.3%), the rest had normal images of the ampulla of Vater, no ulcers or changes in mucosal color. Biopsy results: 23 ampullary cancers, 1 grade 2 neuroendocrine tumor, 6 inflammatory lesions corresponding to 4 patients with common bile duct cancer and 2 patients with pancreatic head cancer.
The results of detecting Vater tumor during gastroduodenoscopy in Nguyen Tan Cuong's study (2004) were 72/75 cases (95.8%), and Nguyen Ngoc Bich's (2009) study was 24/29 patients [113],[120].
4.1.3.7. Endoscopic ultrasound results
The study included 27 patients who underwent preoperative endoscopic ultrasound with a rate of dilated common bile duct (92.6%), dilated pancreatic duct (66.7%), 100% tumor detection, and adenocarcinoma rate of Vater in 17/20 (85%) of biopsy specimens. Our tumor detection rate (100%) was high because most of the tumors were T2 or higher, with no cases of Tis or T1 (Table 3.11).
Endoscopic ultrasound can determine the location of suspected metastatic lymph nodes, tumor invasion into the blood vessels around the tumor, and predict the possibility of performing laparoscopic pancreaticoduodenectomy. Most authors agree on the criteria for diagnosing metastatic lymph nodes based on 4 criteria: round or elliptical lymph nodes, hypoechoic, clear margins, and size ≥ 1 cm. SANS accurately diagnoses lymph nodes 64% - 82% [121].
Nawaz (2013), analyzed 512 patients and showed that: endoscopic ultrasound diagnosis of abdominal lymph nodes has a sensitivity of 69%, specificity of 81%, positive prediction of 81%, negative prediction of 65% and diagnostic accuracy of 83%. Compared with postoperative pathology, endoscopic ultrasound has a probability of correctly diagnosing Vater ampullary tumors at T1, T2, T3 + T4 of 50%, 81.8%, 69.2%, respectively [122].
4.2. INDICATIONS AND CHARACTERISTICS OF ENDOSCOPIC SURGERY
4.2.1. Indications for laparoscopic pancreaticoduodenectomy
Clinical practice shows that in many cases, preoperative diagnosis is very difficult due to invasive tumors, unable to define the lesion boundary. Absolute indications are cancers around the ampulla of Vater, not invading the superior mesenteric artery, not metastasizing to the peritoneum, the patient's physical condition allows, and the surgeon is capable of laparoscopic pancreaticoduodenectomy [113],[123].
About tumor location:
Wang (2015) selected tumors located in the ampulla of Vater, duodenal tumors limited to segment D2, tumors in the lower part of the common bile duct, and localized pancreatic head tumors [2]. We prioritized ampulla of Vater tumors (up to 80%) for a number of reasons such as:
small size, less adhesion, convenient for endoscopic dissection. In major surgical centers around the world, Vater tumors account for a higher proportion than common bile duct and duodenal tumors but less than pancreatic head tumors. The proportion of Vater tumors in the study of Asbun (2012) was 15.1%, Dokmak (2015) was 26%, Senthilnathan (2015) was 31.5%,
Delito (25%) [7],[14],[76],[124].
The incidence of low bile duct cancer in Cameron's (2015) study was 8.7% [43], and in Gumbs' (2011) study was 7% [125]. Petrova (2017) studied 228 patients in five centers in Germany and Russia and found that the regional lymph node metastasis rates of tumors in T1, T2, and T3/T4 were 0%, 45.2%, and 56.8%, respectively. The survival rates after 1-, 3-, and 5-years after surgery were 78%, 44%, and 27%, respectively [8]. Therefore, pancreaticoduodenectomy with regional lymph node dissection is an absolute indication if the patient's condition allows. The rate of common bile duct tumors treated laparoscopically in Song's (2019) study was 12.2%. The author performed standard lymph node dissection for cancers located in the lower common bile duct and ampulla of Vater, including suprapyloric and infrapyloric lymph nodes, lymph nodes along the common hepatic artery, hepatic pedicle lymph nodes, and lymph nodes around the head of the pancreas [12].
Pancreatic head tumor: found in 2 (9.4%) patients and all were pancreatic adenocarcinoma. The rate of pancreatic head cancer in the study of Asbun (2012) was 41.5% [76], Croome (2015) was 100% [14], and Senthilnathan (2015) was 44.6% [7],
Delito's (2016) is 54% [124].
Neuroendocrine tumors: classified by WHO as malignant lesions . Dogeas (2017) retrospectively reviewed 101 patients with neuroendocrine tumors in the periampullary region of Vater and found that tumor size was related to the rate of regional lymph node metastasis. When the tumor was < 1 cm, 1-2 cm and > 2 cm, the lymph node metastasis rates were 4.5%, 72% and 81%, respectively. Therefore, tumors > 1 cm in size determined by gastrointestinal endoscopy or endoscopic ultrasound should be indicated for pancreaticoduodenectomy and lymph node dissection [126]. Lubezky's study (2017) followed 32 patients for up to 228 months and found that the tumor recurrence rate was 9.3%, of which 6.25% of patients had
Liver metastasis, 3.1% of patients had peritoneal and lymph node metastasis, 5-year and 10-year disease-free survival were 96.5% and 89.6%, respectively [127].
Compared with some domestic and international studies, we did not encounter pancreatic pseudopapillary solid tumors, duodenal mesenchymal tumors (GIST), metastatic tumors to the pancreas, or cancerous pancreatic cysts [20], [43]. According to the research results of Song (2019), the rate of autoimmune pancreatitis was 20.8%, 2.6% duodenal tumors, 2.4% duodenal GIST, and 12.2% neuroendocrine tumors [12]. According to the WHO classification, GIST is classified into the potentially malignant group. After the conference in the US in 2001, GIST was classified into the malignant tumor group, the prognosis is mainly based on two indicators: tumor size and the number of divisions/50 x 400 microscopic fields. Histopathology divides malignancy into four risk levels: very low, low, intermediate, and high risk. Surgical treatment is the main treatment, and after surgery, depending on the malignancy, adjuvant chemotherapy (Imatinib or Glivec) will be given [128]. Intraductal papillary mucinous neoplasms (IPMNs): This type of tumor accounts for 15 - 30% of pancreatic head cystic tumors, it is considered a precancerous stage, about 20% - 30% of complications into pancreatic ductal adenocarcinoma [129], [130]. According to the American Society of Radiology (2017), based on multi-slice CT scan, it is possible to see lesions with a risk of malignancy such as: cyst size ≥ 3 cm, thick and contrast-enhanced cyst wall, enlarged lymph nodes ≥ 5 mm, pancreatic duct size ≥ 5 mm [131]. According to the recommendations of the European Society for the Study of the Pancreas (2018), surgery is indicated for intraductal papillary mucinous neoplasms of the pancreatic head when: (i) the size of the main pancreatic duct is from 5 - 9.9 mm, (ii) the size of the pancreatic head cyst ≥ 40 mm or (iii) lymph nodes around the pancreatic head ≥ 5 mm [132].
Duodenal adenocarcinoma: relatively rare, with a frequency of 0.4 - 0.6/10 5 in men and 0.3 - 0.5/10 5 in women, with a 1- and 5-year survival rate of 35.9% and 16.1% [133]. Preoperative diagnosis, we encountered only one case (3.1%) with a lesion located in the duodenal wall. This was a 59-year-old female patient with symptoms of duodenal stenosis, gastroscopy showed extensive infiltrative lesions around the duodenum, ulcerated Vater ampulla, easy bleeding, total bilirubin = 4 µmol/l, common bile duct size 6 mm. Postoperative pathology showed cancer.
Vater ampulla. When tumors around the ampulla of Vater progress and invade surrounding structures, it is difficult to make a preoperative diagnosis of whether the lesion is ampulla of Vater cancer invading the duodenum or vice versa. The gold standard is based on the results of postoperative pathology.
Most studies have shown that the best indications for laparoscopic surgery in general and laparoscopic pancreaticoduodenectomy in particular are tumors of the ampulla of Vater, followed by tumors of the pancreatic head and tumors of the lower part of the common bile duct in the early stages. Pancreatic tumors combined with chronic pancreatitis should be limited in their indications because of adhesions, bleeding, and a high conversion rate to open surgery [2], [12], [134].
- Regarding tumor size: In the study, tumor size around the ampulla of Vater was assessed preoperatively based on ultrasound, computed tomography, magnetic resonance imaging and endoscopic ultrasound. The proportion of tumors with size
< 30 mm on ultrasound, CT, MRI and endoscopic ultrasound were 9/9 (100%), 16/18 (88.9%), 11/11 (100%) and 26/27 (96.3%) patients, respectively (Table 3.13). In Dellito's study (2018), patients selected for laparoscopic surgery had an average size of 2.5 cm, which was statistically significantly smaller than the open surgery tumor size of 3.1 cm [124].
Before surgery, authors often rely on computed tomography, magnetic resonance imaging and endoscopic ultrasound to assess the degree of vascular invasion around the tumor, distant metastasis and tumor size. The average tumor size in the study of Dokmak (2015) was 2.82 (1.2 - 4) cm, of Caruso (2017) was 3.1 (1.8 - 3.5) cm, of Tan (2019) was 2.1 (1 - 3.5) [14],[98],[135]. Most authors choose tumors ≤ 4 cm in size when indicating laparoscopic pancreaticoduodenectomy [136].
4.2.2. Characteristics of endoscopically assisted surgery
4.2.2.1. Step 1: Place trocar.
Trocar placement: all patients were placed with 5 trocars in a U-shape towards the pancreaticoduodenal head. Of these, we used 3 10 mm trocars for the following positions: umbilical trocar (for camera and CO2 insufflation ) , right and left white line trocars (surgeon's working channel), 2 5 mm trocars for the position
right and left subcostal area for assistants 1 and 2 to retract the liver, lift the gallbladder, retract the colon, retract the stomach, lift the small intestine loop or use a suction machine to aspirate fluid. This trocar placement method is similar to the studies of Cho A [86], Mendoza [97] and Liao [137]. With five trocar positions placed, we did not encounter any difficulty in the process of resecting the pancreatic head duodenum.
Laparoscopic surgery and assisted laparoscopic surgery have the advantage over open surgery of avoiding large abdominal incisions, reducing the risk of surgical site infection, abdominal wall rupture, and surgical site hernia. The number and location of trocars depend on the surgeon's habits and experience for the surgery to be successful. In most cases, we placed trocars below the umbilicus (93.8%) and did not encounter any complications when placing trocars. In some studies, complications may occur such as trocars going in the wrong direction, causing dissection of the fascia, piercing the greater omentum causing bleeding or intestinal perforation [100]. Therefore, to avoid these complications, we often use two clamps to clamp the umbilicus to lift the abdominal wall, make a 1 cm subumbilical skin incision starting from the lower edge of the umbilicus, trying to go right in the midline, the depth must go through the fascia layer, then use a forceps to puncture the peritoneum of the abdominal wall.
4.2.2.2. Step 2: abdominal exploration
Assessing the possibility of resecting the pancreaticoduodenal mass through laparoscopic observation is a rather important step and also more difficult than open surgery because the tumor cannot be directly touched. Normally, we will check the level of cholestasis of the liver, whether there is liver or peritoneal metastasis, the level of abdominal fluid, the nature of the peritoneal adhesions after the previous surgery or after acute pancreatitis, observe the hepatic pedicle, hepatic pedicle lymph nodes and the upper edge of the pancreas, the tumor's invasion of the transverse colon mesenteric vessels, intestinal loops, uterus and adnexa (in women).
The study showed that the signs of biliary obstruction were the most common, in which gallbladder distension was 83.3%, and cholestatic liver was 66.7%. In addition, peritoneal adhesions occurred in 6.7% (one case after laparoscopic cholecystectomy, one case after acute pancreatitis), and superior jejunal adhesions were 3.3% (Table 3.15). The characteristics of gallbladder distension and cholestatic liver were similar to those in the study of Hoang.
Cong Lam (2018) was 77.8% and 66.7% and Ho Van Linh (2016) was 81.8% and 75% [21],[100]. In fact, many patients come to the hospital because of symptoms of obstructive jaundice and pain under the right rib cage, which are common symptoms of cancer around the ampulla of Vater.
4.2.2.3. Kocher procedure – pancreaticoduodenal mass release
In this step, we open the lesser omentum, carefully evaluate whether the lymph nodes along the hepatic artery are numerous or few, large or small in size, and whether the superior pancreatic portal vein is likely to be infiltrated or not. Next, release the duodenum mass of the head of the pancreas using the Kocher procedure to assess the degree of surrounding invasion, especially invasion of the superior mesenteric fascicle, from which we decide whether to continue performing the pancreaticoduodenal resection or not. For patients with ampulla of Vater tumors and common bile duct tumors, the Kocher procedure is relatively easy, in contrast to cases of tumors in the head of the pancreas with acute pancreatitis, which are often difficult to dissect and easily cause complications because of tumor adhesion and bleeding.
This step study had 3.3% of superior mesenteric vein bleeding complications . This complication occurred when the right edge of the superior mesenteric vein was exposed. In some cases, small veins from the head of the pancreas could be severed during dissection, causing bleeding. Duodenal perforation occurred in one case (3.3%) when using an ultrasonic knife to release the pancreaticoduodenal mass. This injury did not cause much bleeding but caused digestive fluids (bile, pancreatic juice, intestinal juice) to flow into the abdominal cavity, the surgical field would be dirty, causing abdominal infection and limiting laparoscopic surgery (Table 3.16).
When the pancreaticoduodenal mass is separated from the vena cava and the left renal vein is visible, laparoscopic dissection can be performed. On the contrary, when the pancreatic head has signs such as: (i) inflammation and adhesion of the pancreatic head, difficulty in performing the Kocher procedure; (ii) the superior edge of the pancreas is infiltrated, the hepatic pedicle is edematous; (iii) the tumor is adherent to the mesentery of the colon, the mesentery of the colon is inflamed and swollen; (iv) the tumor infiltrates the superior mesenteric vein, then open surgery should be performed.