Surgical Therapy of Gastric Carcinoma
Gastric carcinoma is one of the most common solid malignancies worldwide, with an incidence of over 1 million new cases [1]. In Germany, the incidence is approximately 15,000 new cases per year (about 9,000 men and 6,000 women), with the current 5-year survival rate depending on gender between 30% (men) and 33% (women) [2]. While in Asia, 5-year survival rates of over 70% are achieved due to screening programs, gastric carcinoma often presents at an advanced stage at initial diagnosis in this region, which can no longer be removed locally by endoscopic resection.
The only option for curative therapy in locally advanced gastric carcinomas and adenocarcinomas of the esophagogastric junction (AEG) is currently the oncological-surgical resection with the aim of complete removal of the primary tumor (tumor-free resection margins, R0) and the regional lymphatic drainage pathways (systematic D2 lymphadenectomy) [3].
Endoscopic Submucosal Dissection (ESD)
An exception is early carcinomas (pT1a and N0), which can be resected en-bloc endoscopically, provided they meet all of the following four criteria [3]:
- < 2 cm in diameter
- not ulcerated
- mucosal carcinoma
- intestinal type or histological differentiation grade good or moderate [G1/G2)
Since some criteria (grading, submucosal invasion) are only available after precise histopathological diagnosis, endoscopic resection can initially be performed for diagnostic purposes. However, it should be ensured that this is done with the aim of an en-bloc R0 resection. Endoscopic submucosal dissection (ESD) is the method of choice, as it allows a safe en-bloc R0 resection regardless of size.
Gastric early carcinomas with a maximum of one "extended criterion" can also be resected endoscopically in a curative manner [3]:
- differentiated mucosal carcinoma (G1/G2) without ulceration and size > 2 cm
- differentiated mucosal carcinoma with ulceration and size ≤ 3 cm
- well-differentiated carcinomas with submucosal invasion < 500 µm and size < 3 cm
- undifferentiated mucosal carcinoma < 2 cm in diameter (provided no biopsy evidence of tumor cells within ≤ 1 cm distance exists)
If more than one extended criterion is present, an oncological-surgical resection should be performed [3].
Oncological-Surgical Resection
In addition to total and transhiatal extended gastrectomy, depending on the indication and tumor size, partial gastric resection in the form of proximal or distal gastric resection is possible.
In the case of gastric early carcinoma, the indication for surgery exists whenever the carcinoma confined to the mucosa (T1a) cannot be resected curatively endoscopically, or when a greater depth of penetration (T1b) increases the risk of lymph node metastases and an adequate lymphadenectomy is essential for achieving a cure [3, 4].
For early carcinomas, there is high evidence that laparoscopic procedures are technically safe and oncologically comparable to open surgery, regardless of tumor location and type of resection [5-18]. Compared to conventionally open-operated patients, patients recover faster after laparoscopic resection, show significantly earlier oral tolerance of food intake, reduced postoperative atony, faster mobilization, and a shorter hospital stay [5, 9-11, 16-18]. Overall morbidity after laparoscopic surgery is significantly lower in RCTs: laparoscopic vs. open 2.0-2.8% vs. 2.0-57.1% [13,18]. The 30-day mortality of the laparoscopic and open technique is equal at 0.1-3.0% [4, 5, 19]. An LAD with more than 25 removed lymph nodes and a D2-LAD can be performed laparoscopically without increasing morbidity [17].
Sufficient data is available to make reliable statements about the oncological outcome after laparoscopic resection of gastric early carcinomas. In the Korean COACT0301 trial, a 5-year DFS (disease-free survival) of 98.8% was found in the laparoscopic group and 97.6% in the conventionally open group. The 5-year overall survival was almost identical at 97.6% in the laparoscopic group and 96.3% in the open group [20]. Other comparative studies came to similar results [11, 21].
For locally advanced gastric carcinomas that are proximally located, gastrectomy is usually required. For adenocarcinomas of the esophagogastric junction (cardiac carcinoma, AEG Type II and III), distal esophageal resection is also indicated. Depending on the luminal tumor spread, subtotal esophagectomy with proximal gastric resection or esophagogastrectomy may be necessary to achieve an R0 resection. For distal tumors, the proximal stomach can be preserved without worsening the prognosis. A sufficient resection margin of 5 cm (intestinal type according to Lauren) or 8 cm (diffuse type according to Lauren) should be aimed for. If the safety margin is undershot orally, a rapid section examination should take place. Structures adherent to the tumor (e.g., diaphragm, spleen) should be removed en-bloc with the tumor if possible. Routine splenectomy should be avoided [22-27].
Numerous studies are now available for laparoscopic procedures for curative surgery of gastric carcinoma, which have a high level of evidence for distal, locally advanced carcinomas and distal or subtotal gastric resections, combining both technical feasibility and oncological outcome with the advantages of better early postoperative recovery [19, 28-42]. For proximally located advanced carcinomas, the safety of laparoscopic techniques is proven, but evidence-grade 1 studies (RCT) for oncological equivalence are still pending.
The current German S3 guideline (update 2019) currently recommends laparoscopic procedures for curative surgery of gastric carcinoma "not generally" [3]. The goal of cure should be pursued in all functionally operable patients with T1-T4 tumors [43]. Patients with T4b tumors involving non-resectable structures and those with distant metastases should not undergo radical surgery.