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ORIGINAL ARTICLES |
From the General Surgery Department, Clínica Universitaria, University of Navarra (AS, FMR, JLH-L, FP, JA-C), and Epidemiology (MAM-G), School of Medicine, University of Navarra, Pamplona, Spain.
Correspondence: Address correspondence and reprint requests to: A. Sierra, MD, General Surgery Department, Clínica Universitaria, University of Navarra, Avenida Pío XII, No. 36, 31008 Pamplona, Spain; Fax: 34-948-296500; E-mail: asierra{at}unav.es
| ABSTRACT |
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Methods: We retrospectively assessed 85 patients who underwent a limited lymphadenectomy (D1) and 71 who had an extended lymph node dissection (D2) in a single institution between 1990 and 1998 (median follow-up, 37.3 months). Prognostic factors were assessed by Cox proportional hazard models adjusted for potential confounders.
Results: We found no significant difference in the length of hospital stay (median, 12.1 and 13.1 days), overall morbidity (48.2% and 53.5%), or operative mortality (2.3% and 0%) between D1 and D2, respectively. Five-year survival in the D2 group was longer (50.6%) than in the D1 group (41.4%) for tumor stages (tumor-node-metastasis) >I. In multivariate analysis, tumor-node-metastasis stage (hazard ratio for stages >I vs. 0I, 11.6), the ratio between invaded and removed lymph nodes, the presence of distant metastases, Laurén classification, and the extent of lymphadenectomy (hazard ratio for D1 vs. D2, 2.3; 95% confidence interval, 1.254.30) were the only significant prognostic factors.
Conclusions: Our experience shows that extended (D2) lymph node dissection improves survival in patients with resected gastric cancer.
Key Words: Extended Lymphadenectomy D2 Gastric cancer
| INTRODUCTION |
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In 1981, the Japanese Research Society for Gastric Cancer4 proposed D2 lymphadenectomy as the proper treatment for gastric cancer; this involved radical gastrectomy with level 2 lymph node dissection. Since then, Western groups5,6 have not reproduced Japanese results in terms of survival and complications. They have found no difference between limited lymphadenectomy and EL, as two large multicenter randomized studies have shown.7,8 However, these studies had problems of protocol violations (incomplete or more extensive lymph node dissections in the different study groups), a high morbidity/mortality rate because there were a large number of experiences in different hospitals, and, at times, an unnecessary extent of organ resection (that includes the excision of the tail of the pancreas). The aim of this study was to investigate the role of extended (D2) lymph node dissection in a group of patients undergoing surgery in a single institution, thus avoiding the problem of protocol violations associated with multicenter prospective trials.79
| METHODS |
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Although we did not use a randomized design, we did not follow a biased assignment of patients to one or another procedure. Changes in recruitment were due to skepticism about EL results reported in different published series.1012
We included resectable patients with any tumor stage (1997 tumor-node-metastasis classification13), except for those with macroscopic distant metastases (bone, hepatic, lung, or peritoneal) and any location, excluding esophageal tumors, affecting the stomach. Patients with positive peritoneal lavage (two cases in D1 and four cases in D2), affected hepatoduodenal lymph nodes, or localized carcinomatosis at the bursa omentalis (one patient in the D2 group) were also included.
Table 1 shows the characteristics of both groups. They differ only in age (8 years younger in the D2 group), type of gastrectomy (56.5% of patients in the D1 group were submitted to a subtotal gastrectomy vs. none in D2), American Society of Anesthesiologists (ASA) index,14 and associated radiotherapy. All these features were properly included in a multivariate model to determine their prognostic value and to control for potential confounding.
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The median follow-up was 37.3 months (25th75th percentile, 16.361.5 months), continued until March 2000, and was complete for all the patients in the study. At the end of this study, 39 patients of the D1 group and 25 patients of the D2 group had died. The remaining 92 patients (46 in D1 and 44 in D2) had no evidence of disease.
End Points
Once confirmed that we had two well-balanced groups of patients, one receiving limited lymphadenectomy (D1 operation) and the other an extended lymph node dissection (a modified D2 operation), our purposes were the following.
Statistical Analysis
Analyses were performed with SPSS 9.0 for Windows (SPSS Inc., Chicago, IL). P < .05 (two sided) was considered statistically significant. The
2 test or Fishers exact test was used to compare qualitative variables. Students t-test (mean and SD) was used for quantitative variables if they were assumed to follow a normal distribution; quantitative nonnormal variables were compared by using the Mann-Whitney U-test or the Kruskal-Wallis test. The effect of each prognostic variable was studied in univariate analyses by using the log-rank test; variables with a P value of <.25 were considered candidates to enter a multivariate Cox regression model15 and were stratified for pathologic tumor stage.
| RESULTS |
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Once specific complications were studied (Table 2), hemorrhage was found in D1 more frequently than in D2 (five patients, due to bleeding through the nasogastric tube at gastroenteroanastomosis). We found that 40% of the D2 patients with a pancreatic fistula underwent an associated distal pancreatectomy.
The median number of dissected lymph nodes was 14.0 in D1 (25th75th percentile, 8.221.0) versus 31.0 in D2 (25th75th percentile, 24.042.0; P < .001). The ratio between the number of invaded and resected lymph nodes (N index) was evaluated in both groups, and we observed 33.8% of patients in D2 group with N index category <20%, compared with 16.5% in D1 (P = .041).
The overall 5-year survival rate was 50.4% (95% confidence interval [CI], 37.95%62.84%) in D1 and 64.9% (95% CI, 53.52%76.28%) in D2 when any cause of death was considered (P = .0309; Fig. 1). When mortality related only to gastric carcinoma for advanced pathologic tumor stages (II to IV) was considered, the 5-year survival rate in D2 was significantly higher (50.58%; 95% CI, 36.34%64.82%) than in D1 (41.45%; 95% CI, 26.99%55.91%; P = .04) (Fig. 2; Table 3).
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| DISCUSSION |
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Gastric cancer recurrence patterns (50% of recurrences take place in regional lymph nodes16) and the good Japanese clinical results seemed to confirm the benefits of this technique. Several nonrandomized Japanese studies2,3,1719 showed a 5-year survival rate as high as 50% or 75% (depending on whether there was tumoral invasion of the regional lymph nodes) when an EL was performed.
Because these data were significantly better than any Western series published,6,20 the EL technique began to be applied by Western surgeons, who, however, observed an increased postoperative morbidity without improved survival rates. Given these conflicting results, two large multicenter randomized studies7,8 were performed and demonstrated no survival benefit with EL. At the same time, several Western authors published nonrandomized studies2125 performed in specialized gastric cancer surgery centers, and these showed a higher survival rate.
In our study, we retrospectively analyzed 156 patients with resected gastric cancer operated on in a single institution by the same group of 3 surgeons. Eighty-one underwent a D1 lymphadenectomy, and 71 underwent an extended (D2) lymphadenectomy consisting of excision of the N1 and N2 Japanese classification lymph node levels4 and those located along the hepatoduodenal ligament, as well as a sampling of para-aortic, retropancreatic, and mesenteric nodes.
We studied two well-balanced groups that differed only in age, ASA index, type of gastrectomy, and associated radiotherapy. No systematic criteria were used to assign patients to a group. We have ample reason to think that no bias existed in the assignment of patients to each group. In addition, we applied a multivariate Cox model to control for confounding, adjusting for all the potential prognostic variables and stratifying for tumor stage.15
In relation to postoperative morbidity, we did not find any significant difference between the D1 and D2 groups. Operative differences observed (duration of surgery and production and maintenance of drains) did not imply a longer hospital stay in D2 (13.1 days) than in D1 (12.1 days), unlike data published by other authors.7,8,26
Overall morbidity was similar in D1 (48%) and D2 (53%); although these figures were apparently higher than those reported, this is because lesser complications are included (such as abdominal collections that did not need to be drained, urine infections, phlebitis, and so on). Despite this, the hospital stay (13 days) remains as short and the mortality rate (2%) in our series remains as low as data published by other gastric surgery specialty groups.5,22,23,25
The association of gastrectomy with other organ resection (such as splenectomy or pancreatectomy) has been related to an increased number of complications.20 In our study, we extended the resection to other organs (colon, liver, or pancreas) when the surgeon observed macroscopic infiltration during the operation in the context of a theoretically R0 resection, because this is generally accepted. Nevertheless, we systematically performed splenectomy on all patients submitted to total gastrectomy without observing a higher morbidity, unlike other authors.27
The overall mortality rate (2%, corresponding to two patients in the D1 group who died) was lower than that published by the large multicenter prospective trials.7,8 It seems that the greater specialization of the surgical team plays an important role in considering EL a safe procedure.
In our study, we observed that with the D2 operation, the 5-year survival in patients with tumor stages >I was higher (50.6%) than in the D1 group (41.4%). Multivariate analysis identified D2 lymphadenectomy as one of the five independent prognostic factors. Patients submitted to EL (D2) had a 2.32 times lower risk of tumoral death than those receiving D1, independent of tumor stage. The following variables were identified as other independent prognostic factors: pathologic tumor stage (patients with tumor-node-metastasis stages >I had a 11.66 times higher rate of mortality than those with stages 0 and I), Laurén histological classification (gastric-type tumors presented a worse prognosis than intestinal types), N index (patients with an N index category <20% showed a better prognosis), and the presence of distant metastases (referring to patients with positive peritoneal lavage cytology, invaded hepatoduodenal ligament lymph nodes, or macroscopic localized carcinomatosis at the bursa omentalis).
The median survival follow-up was 37 months; although it is necessary to observe longer-term results, data obtained in our study have relevance if we consider that most tumor recurrences occur within the first 2 years of surgical treatment. These encouraging results are consistent with those observed by Siewert et al.23 and with most Japanese series,2,3,1719 but they differ from the recently published results of randomized multicenter trials.6,20
Recently the Dutch7 and the British (Medical Research Council)8 multicenter randomized studies concluded firmly that D2 is not a safe procedure and does not bring any advantage in the surgical treatment of gastric cancer. The Dutch study7 randomized 711 patients with resectable gastric cancer operated on in 80 different hospitals over 4 years, and it reported similar 5-year survival rates in the D1 and D2 groups (45% and 43%, respectively). Despite being a theoretically well-designed study (supervised by experienced Japanese surgeons), they found 51% of protocol violations (defined as the absence of lymph nodes from more than two lymph node stations that were supposed to be harvested). The Medical Research Council8 studied 400 patients treated with D1 and D2 and obtained no difference in 5-year survival (35% and 33%, respectively); nevertheless, their low median number of dissected lymph nodes (17 in D2 and 13 in D1) is the weak point of that study, because it is generally accepted nowadays that a correct lymphadenectomy must harvest at least a median of 25 lymph nodes.23,28
In our study, the median number of dissected lymph nodes in D2 was 31 and 14 in D1. These data are similar to some recently published series and are of great importance because the number of excised lymph nodes is considered as the quality control for a correct lymphadenectomy29 (the last 1997 tumor-node-metastasis classification13 established a total number of 15 dissected nodes as necessary to properly stage gastric adenocarcinoma). Indeed, some authors9 assert that EL should be used in any patient with resectable gastric cancer simply because it permits a better staging of this disease, because the stage migration phenomenon cannot be demonstrated.
Both of these prospective multicenter studies6,20 are good examples of how difficult randomizing a complex technique can be. They collected a large number of short experiences by many different surgeons and hospitals (80 hospitals in the Dutch study and 35 in the British study), and the likely bias of pooling in these studies might be larger than that of nonrandomized ones.
Although we used a nonrandomized design, our study has the strength of being conducted in a single institution (avoiding the problem of protocol violations) and comparing two well-balanced groups. In addition, we used a multivariate analysis to determine independent prognostic variables. The fact that the type of lymph node dissection performed has been identified as one of the main determinants of survival could add evidence to solve the dilemma about the benefits of lymphadenectomy, because nowadays it is not always possible or ethically correct to randomize patients to a treatment when the application of a different oncologic therapeutic procedure offers unequal results. Our results suggest that EL should be the procedure of choice in the management of resectable gastric cancer at any location, provided that adequate morbidity and mortality figures are maintained.
| Footnotes |
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Received for publication July 8, 2002. Accepted for publication October 15, 2002.
| REFERENCES |
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