Microsatellite instable double primary cancers of the colorectum and stomach exhibit less favorable outcome

Table 1 Clinicopathologic features of double primary gastric and colorectal cancers

Case	Sex	Age (yr)	Onset	Gastric cancer				Site	Colorectal cancer
				Differentiation	T	N	Stage		Differentiation	T	N	Stage
1	Male	49	Synchronous	Diffuse	1	0	1	TC	Moderate	4	1	3/C
2	Male	35	Synchronous	Intestinal	2	0	1	AC	Mucinous	3	2	3/C
3	Male	50	Metachronous	Intestinal	2	0	1	DC	Moderate	3	1	3/C
4	Male	56	Synchronous	Intestinal	1	0	1	C	Moderate	3	1	3/C
5	Male	68	Synchronous	Intestinal	1	0	1	SC	Mucinous	3	0	2/B
6	Male	57	Synchronous	Diffuse	1	0	1	R	Moderate	3	2	3/C
7	Male	54	Synchronous	Intestinal	2	0	1	SC	Moderate	2	0	1/A
8	Male	61	Synchronous	Intestinal	1	0	1	AC	Moderate	2	0	1/A
9	Female	76	Metachronous	Intestinal	1	0	1	TC	Moderate	3	0	2/B
10	Male	65	Synchronous	Intestinal	1	0	1	AC	Moderate	3	0	2/B
11	Female	65	Synchronous	Diffuse	1	0	1	AC	Mucinous	3	1	3/C
12	Male	48	Metachronous	Diffuse	?	?	?	AC	Moderate	3	2	3/C
13	Male	71	Synchronous	Intestinal	1	0	1	AC	Well	3	1	3/C
14	Male	65	Synchronous	Diffuse	1	0	1	SC	Moderate	3	0	2/B
15	Male	59	Synchronous	Intestinal	1	0	1	AC	Mucinous	3	0	2/B
16	Male	61	Metachronous	Diffuse	2	0	1	SC	Moderate	3	1	3/C

C, cecum; AC, ascending colon; TC, transverse colon; DC, descending colon; SC, sigmoid colon; R, rectum.

Table 2 Microsatellite instability (MSI) and follow-up results of double primary gastric and colorectal cancers

Case	Gastric cancer (GC)						Colorectal cancer (CRC)						Follow-up (mo)
	bat26	D5S346	bat25	D17S250	D2S123	MSI	bat26	D5S346	bat25	D17S250	D2S123	MSI
1	●	●			●	H	●		●	⊙		H	21, alive, RGC
													22, alive, RCRC
2	●	●	●	⊙	●	H	●	●	⊙	⊙	⊙	H	88, alive, MGC, kidney
3	●	●	●	⊙	●	H	●	○	●	○	●	H	58, alive, +AOV cancer
4	●	○	●	○	○	H	●	○	●	○	○	H	10, alive, RCRC
5	●	●	●	●	●	H	●	○	⊙	⊙	⊙	I	18, alive, NED
6	○	○	●	○	○	L	⊙	⊙	⊙	⊙	⊙	I	38, alive, NED
7	○	○	○	○	○	S	○	○	○	○	○	S	29, alive, NED
8	○	○	○	○	○	S	○	○	○	○	○	S	18, alive, NED
9	○	○	○	○	○	S	○	○	○	○	○	S	114, alive, NED
10	○	○	○	○	○	S	○	○	○	○	○	S	85, alive, NED
11	○	○	○	○	○	S	○	○	○	○	○	S	61, alive, NED
12	○	○	○	○	○	S	○	○	○	○	○	S	82, alive, NED
13	⊙	⊙	⊙	⊙	⊙	I	○	○	○	○	○	S	19, alive, NED
14	○	○	○	○	○	S	⊙	⊙	⊙	⊙	⊙	I	17, alive, NED
15	⊙	○	⊙	⊙	⊙	I	○	○	○	○	○	S	29, alive, NED
16	⊙	○	⊙	⊙	⊙	I	○	○	○	○	○	S	67, alive, MCRC, lung

H, MSI-high; L, MSI-low; I, inconclusive; NED, no evidence of disease; RGC, recurrent gastric cancer; RCRC, recurrent colorectal cancer; MGC, metastatic gastric cancer; MCRC, metastatic colorectal cancer; AOV, ampulla of Vater.

Table 3 Differences of double primary gastric and colorectal cancers according to microsatellite instability (MSI)

	Both MSI-high (n = 4)	Others (n = 12)	P
Male : Female	4:00	10:02	NS
Age (yr)	47.5 ± 8.9 (35-56)	62.5 ± 7.6 (48-76)	NS
Gastric cancer
- intestinal : diffuse	3:01	7:05	NS
- size (cm)	2.8	3.1	NS
Colorectal cancer
- tubular : mucinous	3 : 1	9 : 3	NS
- size (cm)	4.7	4.2	NS
- node metastasis	100%	25%	NS
- Dukes A : B : C	0 : 0 : 4	2 : 5 : 5	NS
Recurrence, metastasis,	100%	8.3%	< 0.005
or other organ malignancy

NS: not significant.