Surgical Therapy of Distal Gastric Carcinoma
The goal of surgical therapy for gastric carcinoma in all potentially curable stages is to completely remove the tumor along with its lymphatic drainage area and to extend the procedure in cases of infiltration of adjacent organs in the sense of an extended en-bloc resection to achieve an R0 situation.
For a long time, gastrectomy was considered the standard for the treatment of gastric carcinoma until randomized studies could unequivocally demonstrate that total gastrectomy for gastric carcinoma in the distal third has no advantage over subtotal gastric resection in terms of achieving an R0 resection (3, 8). Based on the recommendations of the Japanese Gastric Cancer Association (see Guidelines) and the German Gastric Cancer Study 1992 (15), the tumor location is primarily decisive in the selection of the extent of resection:
- Carcinoma in the distal third of the stomach → subtotal 4/5 resection
- Carcinoma in the middle third → gastrectomy
- Carcinoma in the proximal third with involvement of the cardia → extended gastrectomy with transhiatal resection of distal esophageal segments
Other indications for total gastrectomy include linitis plastica, a special form of gastric carcinoma that leads to diffuse infiltration of the gastric wall (usually signet ring carcinoma), and carcinomas affecting multiple anatomical subregions (upper, middle, and lower third of the stomach).
Subtotal, Distal Resection versus Gastrectomy in Gastric Carcinoma
While in early gastric carcinoma of the intestinal type, tumor spread is predominantly within macroscopically recognizable boundaries, in advanced stages, especially in the diffuse type, discontinuous growth may occur, so that a macroscopically inconspicuous gastric wall can be misleading. To achieve an R0 resection, an oral safety margin of 8 cm in situ should be maintained for the diffuse type, and 5 cm for the intestinal type. From this perspective, in early gastric carcinoma of both types and in the intestinal type in advanced stages with tumor location in the middle and distal third, a subtotal, distal gastric resection is indicated. With knowledge of the histological classification of the tumor type and adherence to the recommended oral safety margins, the extent of resection can thus be planned preoperatively (9, 13, 14).
In subtotal, distal gastric resection, to achieve tumor-free status at the oral resection margin, removal of approximately 80% of the aboral stomach is required. The proximal resection plane should be about 2 cm subcardially on the lesser curvature side and above the confluence of the right and left gastroepiploic vessels on the greater curvature, with the distal resection boundary approximately 3 cm postpyloric. In addition to gastric resection and lymphadenectomy, resection of the lesser omentum with liver-proximal transection and subtotal resection of the greater omentum are required. The latter is completely resected in gastrectomy (14, 17).
For carcinomas in the proximal third of the stomach, a transhiatal extended gastrectomy is necessary. A transthoracic approach is only indicated if tumor-free status at the distal esophageal resection margin cannot be achieved with the transhiatal approach, which can be verified by intraoperative frozen section examination. A primary transthoracic approach is not recommended (13, 17).
Studies have shown that for tumor locations in the middle and distal third, subtotal, distal gastric resection and gastrectomy lead to identical treatment outcomes. There is no significant difference in postoperative morbidity and mortality, and with consideration of oral safety margins, there are no differences in five-year survival rates. However, subtotal resection generally offers better quality of life than gastrectomy (3, 8, 17).
Currently, the various resection procedures are predominantly performed conventionally. The number of laparoscopically performed resections, especially in early gastric carcinoma, is steadily increasing, but a final assessment of the value of minimally invasive techniques is currently not possible due to the lack of randomized studies with larger case numbers and long-term results (2, 10, 18).
Reconstruction of Intestinal Passage
After subtotal, distal gastric resection, the intestinal passage is generally restored by an end-to-side gastrojejunostomy. To spare patients a very burdensome bile reflux with reflux gastritis (in gastrectomy: esophagitis), a Roux-Y reconstruction with a loop at least 40 cm long between the oral anastomosis and Roux-Y jejunojejunostomy is recommended. A Braun's anastomosis does not completely prevent alkaline reflux.
Lymphadenectomy (“LAD”)
In addition to an R0 resection, the extent of tumor spread through the lymphatic drainage pathways is a significant prognostic factor for gastric carcinoma, so the lymphatic drainage area of a gastric carcinoma should also be resected with an adequate safety margin to improve the patient's prognosis, which is reflected in the removal of a sufficient number of non-cancerous lymph nodes. If less than 20% of the removed lymph nodes are affected, the prognosis is significantly better than with a less favorable lymph node involvement (20). Therefore, as many lymph nodes as possible should be removed, but the benefit of LAD should not be jeopardized by increasing morbidity and mortality.
There are three prospective randomized European studies on the radicality of lymph node dissection in gastric carcinoma that examined LAD in compartment 1 (perigastric lymph nodes) with extended LAD (compartment 1 and 2 = lymph nodes of the left gastric artery, celiac trunk, common hepatic artery, splenic artery, and hepatoduodenal ligament), the so-called D2-LAD (1, 6, 7).
In the Dutch (1) and English studies (6), morbidity and mortality were significantly increased after extended LAD, but in both studies, the proportion of patients who underwent splenectomy and/or pancreatic tail resection was significantly higher. A closer look at the two studies reveals that increased morbidity and mortality were primarily due to complications following pancreatic surgery and especially splenectomy. In the third D2-LAD study (7), spleen- and pancreas-preserving procedures were considered, and no significant difference in morbidity and mortality compared to D1-LAD was observed. A Cochrane review from 2004 emphasizes improved staging accuracy and improved prognosis through D2-LAD (12).
Whether an extension of D2-LAD by additional dissection of paraaortic lymph nodes is useful was investigated in a randomized Japanese study (16). Compared to D2-LAD, morbidity and mortality were only slightly increased, but no significant difference in prognosis could be determined. Therefore, an additional extension of D2-LAD cannot be recommended.
Conclusion: With subtle preparation, morbidity and mortality in D2-LAD are not higher than in D1-LAD. D2-LAD leads to an improvement in the prognosis of gastric carcinoma with consistent avoidance of splenectomy (with/without pancreatic tail resection).
Splenectomy and Pancreatic Tail Resection
A routine splenectomy should not be performed in gastric carcinoma and is not justified in the context of gastrectomy (5). A distal pancreatic resection with/without splenectomy may be useful in a T4 stage, but only if an R0 resection can be achieved (11).
Endoscopic Resection of Early Gastric Carcinomas
Superficial, mucosa-limited early gastric carcinomas (T1aN0M0) can be resected endoscopically, as the risk of lymph node metastasis is 0 – 2%. However, if the superficial parts of the submucosa are already affected, the rate of lymph node metastases increases to 25%. According to the Japanese classification of gastric carcinomas, endoscopic submucosal resection can be performed for mucosal carcinomas with:
- Lesions < 2 cm of the elevated type,
- Lesions < 1 cm of the flat type,
- no ulceration,
- histological differentiation grade good to moderate (G1–G2).
The goal is en-bloc R0 resection with adherence to safety margins depending on tumor histology (intestinal type: 4 – 5 cm, diffuse type: 5 – 8 cm). Patients with Helicobacter pylori colonization should receive eradication treatment.
Palliative Situations
The current S3 guideline for surgery of gastric carcinoma has issued consensus-based statements for symptomatic tumor stenosis, tumor bleeding, and the treatment of metastases based on existing studies:
Tumor Stenosis
- Stent implantation, gastroenterostomy, jejunal feeding tube, or palliative radiation
- palliative resection: only in exceptional cases, as there is no sufficient evidence
Tumor Bleeding
- endoscopic hemostasis; if not possible or ineffective:
- angiographic embolization
- palliative resection as a last resort
- chronic oozing bleeding: palliative radiation
Metastases
Currently, there is insufficient evidence for the effectiveness of surgical measures for metastases in terms of survival. In individual cases, resection of isolated organ metastases (liver, ovary) without the presence of peritoneal carcinomatosis may be considered.