Minimally Invasive Surgical Resection for Mid-Stage Gastric Cancer




BACKGROUND AND EPIDEMIOLOGY



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Gastric cancer is a global health problem with an estimated one million new cases diagnosed a year.1 It is the third and fifth leading cause of cancer-related deaths worldwide in men and women, respectively.2 It is the fourth leading cause of cancer-related death in the United States, accounting for approximately 11,000 deaths a year.2 The majority of new cases are occurring in developing countries in Asia, South America, and Eastern Europe, with almost half of all new cases diagnosed in China alone.3 Although the overall incidence of gastric cancer has not increased in the United States, tumors located at the gastroesophageal (GE) junction have increased.2



Gastric cancer subtypes in the Eastern countries differ when compared to the United States and other Western countries. Generally, the United States and other Western countries develop a higher incidence of diffuse-type histology and tumors are more commonly located at or around the GE junction.4 The relative distinction has been postulated to reflect cultural, behavioral, and dietary patterns.



Racial and gender variation has been observed in gastric cancer. In the United States, white patients have approximately half the risk for gastric cancer in age-matched minority patients, including blacks, Hispanics, and Asian/Pacific Islanders.5 Moreover, white patients are less likely to die from disease compared to other minorities. For example, black patients are 2.2 times as likely to die from gastric cancer compared to white patients. Similar trends are seen for other minorities including Hispanics and Asian/Pacific Islanders who have 1.8 and 2.2 higher mortality rates compared to whites, respectively.5 Finally, the incidence of gastric cancer in males is double the incidence in women, and men have mortality rates twice as high as women.5




DIAGNOSIS AND STAGING



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The diagnosis of gastric cancer is established by standard upper endoscopy. With this tool, tumor location can be determined and tissue obtained for diagnosis. Endoscopic ultrasound (EUS) offers the additional benefit of assessing tumor depth of invasion and potentially nodal status, although the sensitivity and specificity are operator dependent. EUS has an accuracy of 65% to 92% for T staging and approximately 50% for N staging.6,7 Patients will undergo a computerized tomography (CT) scan of the abdomen and pelvis to improve preoperative clinical staging. Patients then undergo staging laparoscopy to detect occult peritoneal metastases. A review from our institution at Memorial Sloan Kettering Cancer Center of 657 patients with gastric adenocarcinoma without definitive metastatic disease on CT imaging who underwent staging laparoscopy found that 31% of those patients had occult peritoneal metastases.8 Patients without nodal metastases (N0) and early T staging (T1 or T2) on EUS are considered early-stage gastric cancer and may not need staging laparoscopy as the risk of peritoneal metastases is relatively low (4%).9 Some patients may also undergo positron emission tomography (PET) with 18-flurodeoxyglucose (FDG) for staging gastric cancer; however, the National Comprehensive Cancer Network considers this an optional staging modality.6



We will now focus on our discussion on minimally invasive surgical resection techniques for midstage gastric cancer. An important consideration in this patient population is the use of neoadjuvant chemotherapy as has been shown to be effective in improving overall survival according to the MAGIC trial.10




MINIMALLY INVASIVE SURGERY AND GASTRIC CANCER



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The incidence of gastric cancer is significantly higher in the Eastern world, thus experience with minimally invasive resection techniques is greater. The first laparoscopic-assisted distal gastrectomy (LADG) and D1 lymphadenectomy were successfully performed by Kitano et al in 1994.11 The safety and feasibility of laparoscopic resection has been established by Eastern surgeons since that landmark study. The experience of Western surgeons has emerged at a significantly slower pace. In 1999, the first laparoscopic total gastrectomy was performed by Azagra et al12 in the West. This may be explained by various factors including lower disease incidence, the natural history of disease progression, and locally advanced disease precluding laparoscopic resection. Moreover, in the United States almost half of all gastric resections for adenocarcinoma are performed at low-volume centers, where knowledge and experience with advanced laparoscopic surgical techniques are limited. Thus, the majority of gastric cancer resections are performed via an open approach.



The benefits of minimally invasive surgery have been established. Patients experience significantly less postoperative pain, improved cosmesis, shorter hospitalizations, and improved convalescence. Surgical morbidity, mortality, and oncologic outcomes are equivalent to the open approach in experienced hands. The most important principle is maintenance of oncologic principles and oncologic adequacy of resection. Oncologic adequacy is evaluated and measured by margin status, extent of lymph node dissection, and number of lymph nodes procured.




MINIMALLY INVASIVE DISTAL GASTRECTOMY



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Several randomized controlled trials (RCT) and other case series comparing minimally invasive to open gastrectomy for early gastric cancer have been reported (Table 98-1) with a predominance of literature from the East.1317 The LADG was associated with less pain, early patient mobilization, shorter hospitalizations, improved cosmesis, as well as improved quality of life. Kim et al from Korea reported the largest study comprised of 342 patients randomized to either open or laparoscopic distal gastrectomy for stage I gastric adenocarcinoma.17 There were no statistical differences in morbidity, mortality, or short-term outcomes. Nevertheless, the patient population was highly selected and different than Western patients. Those patients in the study were relatively younger (mean age 55 years), thinner (mean body mass index [BMI] 23.5 kg/m2), and healthier (most patients had no other comorbidities and patients with ASA >2 were excluded) than typical Western patients.4,17




TABLE 98-1:

Laparoscopic Versus Open Gastrectomy for Mid-Stage Gastric Cancera


Jan 6, 2019 | Posted by in ONCOLOGY | Comments Off on Minimally Invasive Surgical Resection for Mid-Stage Gastric Cancer

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