Journal of Surgical Oncology 2009;100:111–114

Prognostic Impact of Lymphatic Invasion in Patients With

Node-Negative Gastric Cancer

DAISUKE ICHIKAWA, MD,* TAKESHI KUBOTA, MD, SHOJIRO KIKUCHI, MD, HITOSHI FUJIWARA, MD,HIROTAKA KONISHI, MD, MASAHIRO TSUJIURA, MD, HISASHI IKOMA, MD, MASAYOSHI NAKANISHI, MD,

KAZUMA OKAMOTO, MD, CHOHEI SAKAKURA, MD, TOSHIYA OCHIAI, MD,YUKIHITO KOKUBA, MD, AND EIGO OTSUJI, MD

Division of Digestive Surgery, Department of Surgery, Kyoto Prefectural University of Medicine, Kamigyo-ku, Kyoto, Japan

Background and Objectives: This study investigated the prognostic impact of lymphatic invasion on the outcome of patients with node-negative

gastric cancer.

Methods: A total of 828 patients with node-negative gastric cancer who underwent curative gastretomy were reviewed retro-

spectively. The clinicopathological features and prognoses of patients with lymphatic invasion were compared to those of patients without

such invasion.

Results: The total rate of lymphatic invasion was 18.2% in node-negative gastric cancers, with a significant difference between early gastric

cancers (9.8%) and advanced gastric cancers (49.2%). The presence of lymphatic invasion correlated significantly with tumor location, size and

depth of tumor (P< 0.01). Lymphatic invasion was significantly associated with a poorer overall survival in node-negative gastric cancer patients

on univariate analysis (P< 0.001) as well as multivariate analysis (P< 0.01).

Conclusions: Lymphatic invasion provides additional useful information that could be applied to identify patients at high risk for recurrence who

might be candidates for adjuvant therapies in patients with node-negative gastric cancers.

J. Surg. Oncol. 2009;100:111–114. � 2009 Wiley-Liss, Inc.

KEY WORDS: lymphatic vessel; survival; prognostic factors; invasion

INTRODUCTION

Although the incidence of gastric cancer has decreased significantly

over the past several decades, it remains the second most common

cause of cancer-related deaths worldwide [1]. Since the lymph node

metastasis is one of the most important prognostic factors, both of

the two main staging systems for gastric cancer, the Union

Internationale Contre le Cancer (UICC) and the Japanese Classification

of Gastric Carcinoma (JCGC), defines the stage of the disease

based mainly on status of lymph node metastasis and depth of wall

invasion [2,3].

However, lymphatic invasion has also been recognized as a

significant prognostic factor, strongly associated with potential lymph

node metastasis [4–7]. We have sometimes encountered gastric cancer

patients showing discrepancy between the status of lymph node

metastasis and the degree of lymphatic invasion. Therefore, lymphatic

invasion of tumor cells does not necessarily indicate the lymph node

metastases.

Large-scale randomized studies have recently demonstrated that

post-operative adjuvant chemotherapy is the standard of care after

curative surgery in patients with stage II and III gastric cancers [8,9].

However, since the two main staging systems that are currently

applied to gastric cancer do not include the degree of lymphatic

invasion in the staging system, lymphatic invasion generally is not

included in the determination of whether adjuvant chemotherapy is

indicated or not.

This study investigated the frequency of discrepancy between the

degree of lymphatic invasion and the status of lymph node metastases,

and the clinical significance of lymphatic invasion without lymph node

metastasis in patients with gastric cancer.

MATERIALS AND METHODS

Patients

Between 1974 and 2006, a total of 2,599 patients with gastric

cancer underwent surgical resection at Kyoto Prefectural University of

Medicine Hospital. Of these patients, 828 patients (31.9%) histo-

logically proven node-negative gastric cancer, who underwent curative

gastrectomy with lymph node dissection, were enrolled in this

retrospective study.

The clinicopathological features of these node-negative gastric

cancer patients were retrospectively reviewed using the hospital

database. The presence of lymphatic vessel invasion was determined

by routine hematoxylin and eosin staining of the resected specimens,

and immunostaining using D2-40 antibody (Nichirei, Tokyo, Japan) as

needed. The degree of lymphatic invasion was divided into four

grades according to the Japanese Classification of Gastric Carcinoma

(JCGC): ly0(no lymphatic invasion), ly1(minimal lymphatic invasion),

ly2(moderated lymphatic invasion), ly3(marked lymphatic invasion).

Other histological features were also classified according to the

JCGC [3].

*Correspondence to: Dr. Daisuke Ichikawa, MD, Division of DigestiveSurgery, Department of Surgery, Kyoto Prefectural University of Medicine,465 Kajii-cho, Kamigyo-ku, Kyoto 6028566, Japan. Fax: 81-75-251-5522.E-mail: ichikawa@koto.kpu-m.ac.jp

Received 29 November 2008; Accepted 14 April 2009

DOI 10.1002/jso.21311

Published online 27 May 2009 in Wiley InterScience(www.interscience.wiley.com).

� 2009 Wiley-Liss, Inc.

Follow-up consisted of blood examinations, radiological examina-

tions of the gastrointestinal tract, endoscopic procedures, computed

tomography, and ultrasonography. Follow-up procedures were per-

formed every 3 months for at least 2 years, and continued periodically

for at least 5 years.

Statistical Analysis

Survival rates were calculated by the Kaplan–Meier method, with

the date of gastrectomy as the starting point. Differences in survival

were examined by log-rank test. Multivariate analysis of prognostic

factors related to survival was performed using the Cox proportional

hazard mode. The significance of differences was accepted at P< 0.05.

RESULTS

Clinicopathologic Findings

The mean patient age was 60.9 years (range 22–91), and the

male:female ratio was 2.1:1. The median tumor size was 36mm (range

5–272mm). Six hundred fifty-one of 828 patients (78.6%) had early

gastric cancer (T1). Among the 828 node-negative gastric cancer

patients, lymphatic invasion was present in 151 patients (18.2%), with

a significant difference between early gastric cancer (T1: 9.8%) and

advanced gastric cancer (T2,3: 49.2%; Table I). Other factors, such as

tumor location and tumor size, also correlated significantly with the

presence of lymphatic invasion. However, clinicopathologic factors

such as age, sex, and histological type were not found to be associated

with the presence of lymphatic invasion (Table I).

The 151 patients with lymphatic invasion were classified into three

groups according to the JCGC; 100 patients as ly1, 45 patients as ly2

and 6 patients as ly3. Since only 6 patients were classified as ly3, ly2

and ly3 were grouped into one category (ly2,3) for the further

prognostic study. Meanwhile, all patients showing lymphatic invasion

were classified into one category (ly1,2,3) for further prognostic study

of early node-negative gastric cancers, since there were only 8 patients

in ly2 and no patients in ly3 in the early gastric cancer group.

Survival

Figure 1 shows the survival curves for each group according to the

lymphatic invasion grade. The lymphatic invasion was a significant

prognostic factor on univariate analysis (P< 0.0001). Then, the

survival curves for patients in each early and advanced gastric cancer

are shown in Figure 2. In early gastric cancers, the presence of

lymphatic invasion was a significant prognostic factor (P< 0.05).

Lymphatic invasion greater than ly2 was a significant prognostic factor

in advanced gastric cancers (P< 0.05).

As well as lymphatic invasion, univariate analyses demonstrated that

age, tumor size, and depth of tumor were also significant prognostic

factors of patients with node-negative gastric cancer, but sex, tumor

location, and histological type were not (Table II). Next, these significant

prognostic factors and lymphatic invasion were analyzed by multivariate

analysis. Lymphatic invasion was an independent prognostic factor, as

were age and depth of tumor (Table III).

DISCUSSION

The lymphatic metastasis of tumor cells consists of a highly

complex series of mechanisms as follows; (1) invasion to the stromal

tissues and penetration into the lymphatic vessels; (2) release of tumor

cells from the primary tumor mass; (3) dissemination within the

lymphatic circulating system; (4) adhesion of the tumor cells to the

lymphatic endothelium in lymph nodes; and (5) formation of tumor

deposit [10,11]. Although the details of these steps remain unknown,

the step in which the tumor cells enter the lymphatic flow is the most

important for lymph node metastases. In fact, the lymphatic invasion

has been reported to associate with lymph node metastases [12,13].

We, however, sometimes experienced node-negative gastric cancer

patients with histological findings of lymphatic invasion in the

primary tumors.

There should be several reasons for the discrepancy between

findings of lymphatic invasion and status of lymph node metastasis.

First, there is good likelihood that latent lymph node metastasis existed

between each pair of a sectional plane on routine histological

examinations. Second is the possibility that there might be micro-

metastasis detected by only immunohistochemistry but not by routine

hematoxylin and eosin staining. Another possibility is that the tumor

cells entering the lymphatic flow did not have the ability to adhere to

lymphatic endothelium and develop metastatic deposit in lymph node.

Miyazaki et al. [14] reported that galectin-3 might be involved in

Journal of Surgical Oncology

TABLE I. Clinicopathological Features With or Without Lymphatic

Invasion in Patients With Node-Negative Gastric Cancer

Lymphatic invasion

P valueNegative Positive

Age

<65 413 91

�65 264 60 NS

Sex

Male 457 103

Female 220 48 NS

Location

Upper 94 36

Middle 342 62

Lower 228 53 <0.01

Unknown 13

Size

<3 cm 389 36

�3 cm 288 115 <0.001

Depth

T1 587 64

T2T3 90 87 <0.001

Histology

Diff. 387 82

Undiff. 289 69 NS

Unknown 1

Fig. 1. Survival curve of patients with node-negative gastriccancer according to lymphatic invasion. The lymphatic invasion wasa significant prognostic factor by univariate analysis.

112 Ichikawa et al.

developing lymph node metastasis in gastric cancer. PRL-3 was also

reported to play important roles in lymph node metastasis [15]. These

factors on primary tumor cells might be involved partly in the

discrepancy.

In the present study, we evaluated the lymphatic invasion by routine

hematoxylin and eosin staining and immunostaining as needed.

Immunostaining was mainly performed to distinguish lymphatic

invasion from blood vessel invasion in the present study. In the present

study, the overall incidence of lymphatic invasion was 18.2% in node-

negative patients, similar to that in previous reports [4]. Lymphatic

invasion was a significant prognostic factor in node-negative gastric

cancer on both univariate and multivariate analyses. Since the

incidences and degrees significantly differed between early gastric

cancers and advanced gastric cancers, we examined the survival impact

separately in each group. In the node-negative early gastric cancer

group, the presence of lymphatic invasion, even minimal lymphatic

invasion (ly1), was a significant prognostic factor. Two patients who

died from recurrences had each developed peritonitis carcinomatosa,

which is an uncommon recurrence pattern for post-operative patients

Journal of Surgical Oncology

Fig. 2. Survival curve of patients with N0 early gastric cancer (A) and N0 advanced gastric cancer (B) according to lymphatic invasion. Thepresence of lymphatic invasion was a significant prognostic factor in node-negative early gastric cancer (P< 0.05). Lymphatic invasion greaterthan ly2 was a significant prognostic factor in node-negative advanced gastric cancer (P< 0.05).

TABLE II. Prognostic Significance by Univariate Analysis of Variables for

Patients With Node-Negative Gastric Cancer

Variables

No. of

patients

5-year

survival (%) P value

Age

<65 504 95.4

�65 324 92.5 <0.05

Sex

Male 560 94.2

Female 268 94.5 NS

Location

Upper 130 92.6

Middle 404 95.8

Lower 281 92.7 NS

Unknown 13

Size

<3 cm 425 96.9

�3 cm 403 91.3 <0.01

Depth

T1 651 92.7

T2T3 177 82.0 <0.001

Histology

Diff. 469 94.2

Undiff. 358 94.4 NS

Unknown 1

Ly

0 677 97.1

1 100 88.8

2, 3 51 69.4 <0.001

TABLE III. Prognostic Significance by Multivariate Analysis of Variables

for Patients With Node-Negative Gastric Cancer

Risk ratio

95% confidence

interval P value

Age

<65 1 <0.01

�65 3.137 1.457–6.753

Size

<3 cm 1 NS

�3 cm 1.184 0.459–3.054

Depth

T1 1 <0.001

T2T3 6.977 2.575–18.904

Ly <0.01

0 1

1 1.651 0.542–5.030

2, 3 4.818 1.889–12.288

Lymphatic Invasion in Gastric Cancer 113

with early gastric cancers. Peritoneal dissemination might have arisen

from tumor cells exfoliated from lymphatic vessels during surgery.

However, the survival of patients with minimal lymphatic invasion

(ly1) was similar to that of those without lymphatic invasion in patients

with node-negative advanced gastric cancers. When we examined the

prognostic impact of lymphatic invasion on multivariate analysis,

because some factors other than tumor stage were also significant

prognostic factors on univariate analysis, lymphatic invasion was a

significant prognostic factor on multivariate analysis again.

Other findings in the present study were that the histological type

did not correlate with either lymphatic invasion or survival in patients

with node-negative gastric cancers. Because lymph node metastasis

was more frequent in undifferentiated gastric cancer [13], the high

frequency of lymph node metastasis in undifferentiated gastric cancer

might depend on the ability of tumor cells to adhere to the lymphatic

endothelium in lymph nodes and form tumor deposits. Other

interesting finding was that tumor location also correlated significantly

with the presence of the lymphatic invasion. The reason is not known

exactly, however, because the tumors located in the upper-third tended

to be more advanced T-stage compared to those of other regions in the

present study (data not shown), the differences might effect the

frequency of the lymphatic invasion.

CONCLUSIONS

In conclusion, the present study clearly demonstrated the prognostic

impact of lymphatic invasion in patients with node-negative gastric

cancer. Intensive chemotherapy and close follow-up should be

recommended for node-negative gastric cancer with lymphatic

invasion, especially those showing moderate or marked lymphatic

invasion.

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114 Ichikawa et al.