2012 EDUCATIONAL BOOK - American Society of Clinical Oncology

GASTRIC CANCER LYMPHADENECTOMY AND OUTCOMES
of perioperative death (odds ratio 0.55–0.74), yet more than
80% of patients were operated on at centers that performed
20 or fewer gastrectomies per year. 7 As most U.S. surgeons
see only a few GC patients a year, they likely err on the side
of more limited LADs in order to avoid excess morbidity and
mortality. In the Intergroup 0116 trial published in 2001,
patients were randomly selected after GC surgery to undergo
no further therapy or chemoradiation, and more than
50% of operations were less aggressive than a D1 LAD (aka
D0 LAD). 9 Despite the performance of less extensive LADs
in the United States, surgical morbidity and mortality rates
for gastric adenocarcinoma are generally much higher in the
United States than in South Korea and Japan. An analysis
of the Nationwide Inpatient Sample from 1998 to 2003 of
more than 50,000 patents with GC found the overall mortality
rate following gastric surgery was 6%. 10 Singleinstitution
series have reported morbidity rates following
gastrectomy of up to 40%. 11
Differences in Survival
Gastric adenocarcinoma frequently metastasizes to regional
nodes. For T1 lesions invading the submucosa, node
involvement is found in approximately 20% of patients. 12
For T2 lesions (invading muscularis propria), the node
metastasis rate increases to more than 50%. There is some
evidence that at least some patients with node metastases
beyond the immediate perigastric (D1) nodes and into D2
nodes can be cured with surgical resection alone. 13 A sizable
minority of GC patients with positive D2 nodes survive for
more than 5 years following D2 lymphadenectomy at the
Japanese National Cancer Center in Tokyo.
Numerous studies have demonstrated decreased overall
KEY POINTS
● More extensive D2 lymphadenectomies are standard
in high-incidence Eastern countries such as Japan
and South Korea, leading to better staging of disease
and likely lower rates of locoregional recurrence.
● In the United States (a low-incidence Western country),
the vast majority of gastric resections are performed
at low-volume (less than 20 cases per year)
centers with generally less extensive lymphadenectomies
and higher morbidity and mortality.
● Stage for stage, overall survival is worse in the
United States than in Japan and South Korea, but
much of this difference could be explained by stage
migration and clinicopathologic differences between
gastric cancers in Eastern versus Western countries.
● The Dutch and U.K. D1 versus D2 lymphadenectomy
randomized trials were flawed, and further prospective
randomized trials of lymphadenectomies performed by
well-trained Western surgeons on Western patients are
needed to determine if there is an overall survival
benefit to more extensive lymphadenectomies.
● Strategies to improve the surgical outcomes of patients
with gastric cancer in low-incidence Western
countries include referral to tertiary centers and
improved training of surgeons.
Fig 1. Location of node stations according to the Japanese Gastric
Cancer Association. 38 (A) Perigastric nodes stations 1 to 7. (B) Second
tier node stations 8 to 12 and 14.
survival (OS) after potentially curative gastrectomy for
gastric adenocarcinoma in the West compared with the East.
Table 3 demonstrates 5-year OS results stage-for-stage from
four large databases based on the sixth American Joint
Committee on Cancer (AJCC) staging system. D2 LADs are
generally performed at the National Cancer Center (NCC) in
Tokyo, Japan, and at SNUH is South Korea. The median
number of examined nodes at both these institutions is
greater than 30, and there is a remarkable similarity in the
5-year survival figures from these two institutions. In the
U.S. Surveillance Epidemiology and End Results (SEER)
database, most patients had either a D0 or D1 LAD, and the
median number of examined nodes is 10 to 11. 14 For stages
I to III, the 5-year survival rate is 14% to 30% lower for
SEER database patients. At Memorial Sloan-Kettering Cancer
Center, where approximately 80% of patients receive a
D2 LAD, 15 stage-for-stage OS is intermediate between
SEER database patients and NCC/SNUH patients. 16 Some
of these differences in 5-year survival can clearly be attributed
to stage migration. 17 As more nodes are harvested,
more malignant nodes can be found, leading to a higher
staging of patients.
There are also clearly some differences in the clinical and
pathologic presentation and adjuvant treatment of GC in the
West compared with the East that make comparison of
outcomes difficult. In terms of patient demographics, West-
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