H. Takemoto and M. Makino

abFig. 2. Immunohistochemical staining of hMLH1 in gastric cancer. hMLH1 protein reveals abundantnuclear stainings in gastric cancer cells which are not deficient in mismatch repair (MMR) (a). MMRdeficient gastric cancer cells (b) show negative staining of hMLH1 protein (original magnification, × 200).

cancer group consisted of 5 patients with synchronous double primary cancer (median age 75.4
years, ranges 68–88 years) and 10 patients withmetachronous double primary cancer. Among the10 patients, 2 patients developed their 1st cancer inthe colorectum at the age of 63 and 69 years, respectively, with the intervals between the 1st and 2ndonsets were 6 and 8 years, respectively. The re120

MMR deficiency in double cancer

Table1. Clinicophathological features of 15 patients with double primary cancer of the colorectumand stomach
Patient Sex
number
12
3
4
5†
6†
7†
8
9*
10†
11
12*
1314†
15M
M
M
M
M
M
M
F
M
FM
M
M
M
F

Colorectal cancer
Gastric cancer
Expression
Age atExpression
Age atDepth
Lymph
Histologicalofdiagnosis
ofdiagnosisofnodedifferMLH1 MSH2 (year) MLH1 MSH2 (year)
invasion metastasis
entiation
–
–++–
–
+–
++–
+++++++++++++++++
–
+

72
70
61
72
68
88
72
71
63
76
63
69
73
73
58

–
–
++++++++++++++++++++++++++++

49
49
50
68
68
88
72
65
71
76
61
75
61
73
47

t3
t1
t2
t1
t1
t1
t1
t3
t1
t3
t1
t2
t3
t1
t2

10
1000010301200

por
por
pap
tub
pap
tubtubpap
tubmuctub
por
por
tubporStage

IIIAIAIIIAIAIAIAIIIAIAIVIAIIIA
IIIBIAIB

t1, invasion within submucosa; t2, invasion from the muscularis propria to submucosa; t3, penetration to serosa; t4,invasion to adjacent organs.
F, female; M, male; muc, mucinous adenocarcinoma; pap, papillary adenocarcinoma; por, poorly differentiatedadenocarcinoma; tub, tubular adenocarcinoma.
* Patients who developed colorectal cancer previous to gastric cancer.
† Patients who developed colorectal and gastric cancer synchronously.

maining 8 patients developed their 1st cancer in thestomach at the median age of 56.3 years (ranges 47–65 years), with the median interval between onsets
of 11.3 years (ranges 2–23 years).
Table 2 compares the clinicopathological findings of CRCs between the double primary cancer
and control groups. The incidence of MMR-deficient CRC was significantly higher (P < 0.05) in thedouble primary cancer group (7/15, 46.5%) than in
the control group (32/155, 20.6%). In the double
primary cancer group, MMR tended to be deficientin patients who were older, had less liver-andlymph-node metastases and were advanced in depthof invasion than in patients of the control group.
In both groups, patients with MMR-deficient
CRC tended to show localization proximal to thecolon (60.0% versus 40.0% and 28.2% versus 17.5%,respectively) and poorly differentiated and muci-nous adenocarcinomas in histology (100% versus
38.5% and 45.1% versus 17.0%, respectively); bothfeatures are characteristics of HNPCC. Furthermore, MMR-deficient CRCs tended to be less invenous invasion (22.2% versus 66.7% and 5.7%
versus 51.0%, respectively) and liver metastasis(0.0% versus 50.0% and 11.1% versus 21.2%, respectively) than non-MMR-deficient CRCs (Table2).
MMR-deficient gastric cancer was immunohistochemically detected in 2 (13.3%) of the 15 patients of the double primary cancer group. The 2
patients had the same deficient MMR gene protein(MLH1) in both CRC and gastric cancer. Furthermore, the 2 patients had several common clinicopathological features: both were male, their cancers
were poorly differentiated in histology and the preceding gastric cancer developed at a younger age.

121

H. Takemoto and M. Makino

Table 2. Clinicophathological features and MMR deficiency in the double primary cancer group andcontrol group
Double cancer group
MMR deficiency
Positive
Number/Total%
Patients
Age (year)

60 ≥
60 <SexMaleFemale
Location of tumor
Proximal
DistalHistological type
Poorly diff. and mucinous
adenocarcinomas
OthersDepth of invasion
t1
t2, t3, t4
Liver metastasis
Positive
Negative
Lymph node metastasis Positive
Negative
Venous invasion
Positive
Negative
Lymphatic invasion
PositiveNegative

Control group
MMR deficiency
Positive
Number/Total%

P value

7/15
7/14
0/1
6/12
1/3
3/5
4/10
2/2

46.7
50.0
0.0
50.0
33.3
60.0
40.0
100

32/155
27/118
5/37
18/75
14/80
11/39
21/116
9/20

20.6
22.9
13.5
24.0
17.5
28.2
18.1
45.0

0.022
0.028
0.693
0.061
0.484
0.151
0.061
0.136

5/13
0/2
7/13
0/1
7/14
2/7
5/8
2/9
4/6
3/5
4/10

38.5
0.0
53.8
0.0
50.0
28.6
62.5
22.2
66.7
60.0
40.0

23/135
1/13
31/142
1/9
31/146
9/45
23/1106/104
26/51
14/63
18/92

17.0
7.7
21.8
11.1
21.2
20.0
20.9
5.7
51.0
22.2
19.6

0.060
0.685
0.010
0.725
0.016
0.606
0.008
0.065
0.467
0.060
0.136

t1, invasion within submucosa; t2, invasion from the submucosa to the muscularis propria; t3, penetration to serosa;
t4, invasion to adjacent organs.
diff., differentiated; MMR, mismatch repair.

a more important role in carcinogenesis in the colorectum than in other extracolonic sites.
MMR-deficient CRC shows localization in theproximal colon and poor histological differentiation, which are characteristics of HNPCC. As reported, genetic instability might play an importantrole in developing multiple primary CRC (Horii etal., 1994); however, our data suggested that patientswith MMR-deficient CRC may also have a risk ofdeveloping double primary cancer. Furthermore,
MMR-deficient CRCs were more advanced in
depth of invasion but less frequent in venous invasion and liver metastasis than non-MMR-deficient
CRCs. This tendency was more marked in the double primary cancer group than in the control group.
Tumors with an MMR deficiency might affect somefactors and suppress spreading cancer cells.

Discussion
Multiple CRC occurs in 5 to 10% of CRC patients(Enker et al., 1978; Rennert et al., 1995), and over
85% of multiple CRC patients show MSI (Horii etal., 1994; Masubuchi et al., 1999). In our study, theincidence of double primary cancer was 8.8% (15/170) in CRC patients, and the incidence of an MMR
deficiency in CRC of double primary cancer patients was 46.7% (7/15), consistently with a reported level (Kim et al., 2001). The incidence of multiple CRC and that of double primary cancer weresimilar in CRC patients; however, the incidence ofan MMR deficiency was lower in double primarycancer patients than in multiple CRC patients.
These findings indicate that MMR deficiency plays

122

MMR deficiency in double cancerand Clinical Science, Department of Multidisciplinary
Internal Medicine, School of Medicine, Tottori
University Faculty of Medicine, for their critical readingof the manuscript.

MMR-deficient tumors reduce the expressionof COX-2 protein (Karnes et al., 1998) and suppress
the expression of vascular endothelialgrowth factor.
This factor is very potent in tumor angiogenesis andplays an important role in the migration and growthof vascular endothelial cells, the promotion of vascular permeability and the formation of vascular canals (Connolly et al., 1989; Leung et al., 1989).
These reports could explain the few vessel invasions in tumors with an MMR deficiency. Also, in
another of our studies (in submission), we reported
that MMR-deficient tumors tended to express β2microglobulin protein at a lower level than nonMMR-deficient tumors, and that MMR-deficienttumors might evoke an immune response. This also
may be a reason for the favorable prognosis of patients with MMR-deficient CRC.
Of the 15 gastric cancer patients of the double
primary cancer group, 2 patients (13.3%) had an
MMR deficiency, and their deficient MMR geneprotein (MLH1) was the same in CRC and gastriccancer, similarly as reported (Kim et al., 2001). An
MMR deficiency could relate to carcinogenesis ofdouble primary cancer in the colorectum and stomach, but the incidence of an MMR deficiency ingastric cancer was lower than that in CRC. Thus, anMMR deficiency seems to affect the developmentof gastric cancer to some extent, which is not somarked as in development of CRC.
In the present study, we observed that an
MMR deficiency of CRC was more frequent in thedouble primary cancer group than in the controls.
Patients with MMR-deficient CRC or gastric cancer
need periodical and intensive follow-up focusing
not only on metachronous multiple CRC but also on
double primary cancer.

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Received September 16, 2003; accepted November 10, 2003
Corresponding author: Masato Makino, MD124