Multi-institutional Registry of Large Bowel Cancer in Japan Conducted by the Japanese Society for Cancer of the Colon and Rectum in 2023: Cases Treated in 2015

Abstract

Objectives:

Colorectal cancer is the most prevalent malignant disease in Japan. This study aimed to publish data on colorectal cancer cases registered in 2023, involving initial treatments in 2015.

Methods:

Participating facilities of the Japanese Society for Cancer of the Colon and Rectum (JSCCR) registered cases treated in 2015 according to the 8th edition of the Japanese Classification of Colorectal Carcinoma. Data sent to the National Registration Committee in 2023 were analyzed.

Results:

The study analyzed 12,804 cases. Endoscopic treatments were performed in 983 cases, endoscopic treatment followed by surgical resection in 734 cases, and surgeries were carried out in 10,884 cases. Notably, the proportion of laparoscopic surgeries increased significantly from 34.7% in 2010 to 63.5% in 2015.

Conclusions:

This report details the characteristics, treatment methods, and outcomes of colorectal cancer patients who received initial treatment in 2015 at JSCCR-participating facilities. These data should be helpful for patients to understand their disease accurately and for healthcare professionals to explain colorectal cancer and its treatments to patients.

Introduction

The nationwide registration of colorectal cancer cases in Japan began in 1974 and has been continuously carried out annually by the participating facilities of the Japanese Society for Cancer of the Colon and Rectum (JSCCR). The National Registration Committee of the JSCCR has disclosed the results. However, opinions suggested that the results should be published in a more citable format, leading to the committee's decision to publish these findings continuously. This paper aims to disclose the treatment details and outcomes of colorectal cancer cases treated in 2015 and compiled in 2023.

Methods

Cases

JSCCR-participating facilities registered cases treated in 2015 according to the 8th edition of the Japanese Classification of Colorectal Carcinoma. Data sent to the National Registration Committee in 2023 were analyzed, excluding personal information such as facility registration numbers, dates of birth, and names. Registration was voluntary and conducted by willing facilities. The JSCCR and Teikyo University ethics committee approved this registration (93-1 and 20-246).

Statistics

The analysis was performed using JMP 13 software (SAS Institute Japan, Ltd., Tokyo, Japan). Unspecified data were clarified to ensure the accuracy of information. The prognosis was analyzed using the Kaplan-Meier method, and the log-rank test was conducted.

Results

Algorithm of data cleaning

Out of 13,091 registered cases, those with unknown gender, age, final confirmation date, and treatment date were excluded, resulting in 12,804 cases for analysis (Figure 1).

Figure 1.

Patient flow diagram.

Treatment methods

The registered cases comprised 983 endoscopic resections, 734 additional surgeries following endoscopic treatment, 10,884 surgical cases, and 203 non-surgical cases.

Endoscopic treatment cases

Of the 983 endoscopic treatment cases, 62.9% were male and 37.1% were female, with a median age of 68 years (22-93). Table 1 shows the age distribution. The distribution of patients was highest in their 70s, followed by those in their 60s. Table 2 lists the lesion locations, with the sigmoid colon being the most common site, followed by the ascending colon and lower rectum. Table 3 details treatment methods, showing endoscopic mucosal resection (EMR) as the most frequent. Endoscopic submucosal dissection (ESD) was performed in 26.6% of patients. Excluding unknown cases, en bloc resection was achieved in 93.6%. Table 4 shows the macroscopic types of tumors. Among the macroscopic types, Isp lesions were the most common, followed by Ip lesions. Depressed-type lesions accounted for 3.6%. The median size of the lesions was 15 mm (range: 3-115), with the distribution shown in Table 5. Table 6, 7 list histological types and invasion depth, respectively; approximately 80% are pTis. Well-differentiated adenocarcinoma was the most common. Lymphatic and venous invasion were observed in 2.1% and 2.5% of cases, respectively. Positive horizontal and vertical margins were 2.2% and 0.8%, respectively.

Table 1.

Age Classification.

Age classification	Endoscopic excision			Surgery after endoscopic excision			Surgery
	Number	Percentage		Number	Percentage		Number	Percentage
<20	0	0		1	0.1		6	0.06
20-29	3	0.3		0	0.0		38	0.3
30-39	13	1.3		23	3.1		161	1.5
40-49	63	6.4		50	6.8		593	5.4
50-59	156	15.9		145	19.8		1,373	12.6
60-69	297	30.2		261	35.6		3,264	30.0
70-79	313	31.8		198	27.0		3,530	32.4
80-89	132	13.4		55	7.5		1,743	16.0
90=<	6	0.6		1	0.1		176	1.6
Total	983	100		734	100.0		10,884	100

Table 2.

Tumor Location.

Tumor location	Endoscopic excision			Surgery after endoscopic excision			Surgery
	Number	Percentage		Number	Percentage		Number	Percentage
Vermiformis appendix	0	0		0	0		70	0.6
Cecum	31	3.2		37	5		782	7.2
Ascending	130	13.2		80	10.9		1,723	15.8
Transverse	100	10.2		51	6.9		1,030	9.5
Descending	60	6.1		40	5.5		504	4.6
Sigmoid	336	34.2		276	37.6		2,619	24.1
Rectosigmoid	94	9.6		84	11.4		1,409	12.9
Upper rectum	87	8.9		63	8.6		1,105	10.2
Lower rectum	119	12.1		96	13.1		1,411	13.0
Proctos	0	0.0		1	0.1		84	0.8
Unknown	26	2.6		6	0.8		147	1.4
Total	983	100		734	100		10,884	100.0

Table 3.

Endoscopic Excision-Procedure.

Procedure	Number	Percentage
Polypectomy	121	12.3
EMR	561	57.1
ESD	261	26.6
Unknown	40	4.1
Total	983	100.0

Table 4.

Endoscopic Excision-Macroscopic Type.

Macroscopic type	Number	Percentage
Ip	212	21.6
Isp	283	28.8
Is	114	11.6
IIa	146	14.9
IIb	0	0
IIc	3	0.3
IIa+IIc	29	3.0
IIc+IIa	3	0.3
Others	84	8.5
Unknown	109	11.1
Total	983	100

Table 5.

Endoscopic Excision-Tumor Size 2.

Tumor size	Number	Percentage
<=5 mm	36	4.0
6-10 mm	237	26.4
11-15 mm	215	23.9
16-20 mm	180	20.0
21-30 mm	144	16.0
31-40 mm	37	4.1
>40 mm	49	5.5
Unknown	85
Total	983

Table 6.

Histologic Type.

Histologic type	Endoscopic excision			Surgery after endoscopic excision			Surgery
	Number	Percentage		Number	Percentage		Number	Percentage
Well differentiated	820	83.4		417	56.8		3,934	36.1
Moderately differentiated	90	9.2		176	24		5,695	52.3
Poorly differentiated	2	0.2		5	0.7		321	2.9
Mucinous	0	0		4	0.5		386	3.6
Signet ring cell	0	0		0	0		30	0.3
Medullary carcinoma	0	0		0	0		15	0.1
Adenocarcinoma (NOS)	0	0		0	0		22	0.2
Squamous cell carcinoma	0	0		0	0		12	0.1
Neuroendocrine tumor	24	2.4		13	1.8		56	0.5
Others	5	0.5		7	0.1		43	0.4
Unknown	42	4.3		112	15.3		370	3.8
Total	983	100		734	100		10,884	100.0

Table 7.

Endoscopic Excision-Depth of Tumor Invasion.

Depth of tumor invasion	Endoscopic excision			Surgery after endoscopic excision			Surgery
	Number	Percentage		Number	Percentage		Number	Percentage
pT0	0	0		0	0		31	0.3
pTis	784	79.8		61	8.3		360	3.3
pT1a	108	11		76	10.4		198	1.8
pT1b	61	6.2		456	62.1		1,014	9.3
pT1 (NOS)	4	0.4		23	3.1		73	0.7
pT2	2	0.2		25	3.4		1,557	14.3
pT3	0	0		20	2.7		4,877	44.8
pT4a				1	0.1		1,752	16.1
pT4b				1	0.1		588	5.4
Unknown	24	2.4		71	9.7		434	4.0
Total	983	100		734	100		10,884	100

Surgical resection following endoscopic treatment

In 734 cases, additional bowel resection was performed following endoscopic resection. Among these, 60.2% were male and 39.8% were female, with a median age of 66 years (range: 17-97). Table 1 shows the age distribution. Most patients were in their 60s, followed by those in their 70s. Lesion locations are listed in Table 2, with the sigmoid colon being the most common, followed by the lower rectum and rectosigmoid junction. Table 8 details the operative approach, with 89.6% undergoing laparoscopic surgery. Table 9 shows lymph node dissection details; most patients underwent D2 dissection. Histologically, 57.2% were well-differentiated adenocarcinoma (Table 6). Invasion depth was T1b in 62.1% of cases, with T2 and T3 cases at 3.4% and 2.7%, respectively, requiring attention (Table 7). Lymph node metastasis occurred in 11.2% of cases. The median number of dissected lymph nodes was 13 (0-71). Recurrence occurred in 3.3% of cases, with recurrence sites detailed in Table 10. The liver and lung were the most frequent recurrence sites. The 5-year overall survival rate was 95.6%.

Table 8.

Operative Approach.

Operative approach	Surgery after endoscopic excision			Surgery
	Number	Percentage		Number	Percentage
Transanal	2	0.3		76	0.7
Laparoscopic	658	89.6		6,913	63.5
Open	67	9.1		3,642	33.5
Others	0	0		33	0.3
Unknown	7	1.0		220	2.0
Total	734	100		10,884	100

Table 9.

Lymph Node Dissection.

Operative approach	Surgery after endoscopic excision			Surgery
	Number	Percentage		Number	Percentage
D0	8	1.1		190	1.7
D1	16	2.2		364	3.3
D2	423	57.6		2,324	21.4
D3	255	34.7		7,194	66.1
Unknown	32	4.4		812	7.5
Total	734	100		10,884	100

Table 10.

Recurrence Site after Surgery.

Operative approach	Surgery after endoscopic excision		Surgery
	Number		Number
Anastomosis	1		83
Regional lymph node	3		188
Local	1		140
Peritoneal	1		318
Liver	8		675
Lung	8		552
Lymph node (not regional)	1		110
Bone	1		54
Brain	1		18
Adrenal gland	0		18
Skin	0		8
Others	2		78

(overlapping+)

Surgical cases

A total of 10,884 surgical cases were registered, 57.3% male and 42.7% female, with a median age of 70 years (range: 13-101). Table 1 shows the age distribution. Most patients were in their 70s, followed by those in their 60s. Table 2 lists tumor locations, with the most common sigmoid colon followed by the ascending colon and lower rectum. Preoperative CEA levels were normal in 53.3% of cases (Table 11). Synchronous multiple primary cancers appeared in 4.7%, and synchronous multiple colorectal cancers in 6.8%. Table 8 details the operative procedures, with stoma construction in 9.1% of cases. The approach was predominantly laparoscopic (Table 9), with the proportion of laparoscopic surgeries significantly increasing from 34.7% in 2010 to 63.5% in 2015[1]. Lymph node dissection involved D3 dissection in 66.1% of patients (Table 9). The median tumor size was 40 mm, with moderately differentiated adenocarcinoma being the most common histological type (Table 6). The depth of invasion was mostly T3 (Table 7). Positive proximal, distal, and radial margins were 0.3%, 0.4%, and 2.2%, respectively. Lymph node metastasis occurred in 24.4% (N1), 9.6% (N2), and 4.8% (N3) of cases. The median number of dissected lymph nodes was 18 (0-266). Lateral dissection was performed in 737 cases, with a median of 8 dissected lymph nodes (0-58). Curative resection was achieved in 82.6% of cases. Table 12 shows the recurrence rates for each stage. Excluding unknown cases, the recurrence rates for Stage I, II, IIIa, and IIIb were 4.3%, 15.6%, 22.8%, and 41.7%, respectively. The most common recurrence site was the liver, followed by the lung and peritoneum (Table 10). Chemotherapy was the most common treatment for recurrence at 39.4%, with curative resection performed in 32.1% of cases. Figure 2 shows the prognostic curves. The 5-year overall survival rate for the entire cohort was 79.0%, with rates for Stage I, II, IIIa, IIIb, and IV cases at 92.5%, 84.9%, 81.7%, 65.3%, and 35.7%, respectively. Table 13 lists survival rates by stage for colon and rectal cancers. For Stage 0, I, II, IIIa, and IIIb patients, there was no difference in overall survival between colon cancer and rectal cancer. However, for Stage IV patients, the prognosis was significantly worse for colon cancer cases (P = 0.018).

Table 11.

Surgery-Preoperative Serum CEA Value.

Preoperative serum CEA value	Number	Percentage
Normal	5,798	53.3
<2 × ULN	1,898	17.4
<4 × ULN	891	8.2
<8 × UNL	576	5.3
>=8 × UNL	858	7.9
Unknown	863	7.9
Total	10,884	100

Table 12.

Surgery-Recurrence Rate according to Stage.

	Stage 0	Stage I	Stage II	Stage IIIa	Stage IIIb	Stage IV	Unknown	Total
Absent	358 (93.7)	1,992 (91.3)	2,589 (79.4)	1,674 (72.8)	609 (53.6)	537 (48.7)	351 (67.6)	8,110 (74.5)
Present	5 (1.3)	89 (4.1)	479 (14.7)	495 (21.5)	436 (38.4)	197 (17.9)	71 (13.7)	1,772 (16.2)
Unknown	19 (5.0)	100 (4.6)	194 (6.0)	132 (5.7)	91 (8.0)	369 (33.5)	97 (18.7)	1,002 (9.2)
Total	382	2,181	3,262	2,301	1,136	1,103	519	10,884

Figure 2.

The overall survival curves according to the stage of colorectal cancer.

Table 13.

Overall Survival Rates after Surgery (%).

Stage	Colon							Rectum
	Number of patients	1 year	2 years	3 years	4 years	5 years		Number of patients	1 year	2 years	3 years	4 years	5 years
Stage 0	265	98.7	95.6	95.1	92.4	89.4		112	97.1	96.1	94.0	91.7	91.7
Stage I	1,257	98.1	96.8	95.0	93.4	92.0		901	99.2	97.7	96.4	94.8	93.1
Stage II	2,178	96.8	93.3	90.4	87.9	84.6		1,053	98.3	95.1	91.9	88.6	85.5
Stage IIIa	1,438	96.0	91.0	87.3	83.9	80.9		850	98.5	95.3	90.3	86.1	83.1
Stage IIIb	601	91.3	81.3	73.7	68.2	62.9		525	95.5	88.1	79.5	73.3	68.1
Stage IV	746	80.6	62.1	48.8	38.3	34.1		338	84.7	70.6	56.7	46.8	40.3
All	6,485	94.7	89	84.8	81.1	78.0		3,779	97.0	92.7	88.0	84.0	80.9

Limitations

According to regional cancer registry estimates, the incidence of colorectal cancer in 2015 was 140,339 cases[2], meaning this registration covers only 9.3% of the total incidence in Japan. Therefore, the data in this report may not accurately represent the characteristics of colorectal cancer in Japan.

Conclusion

This report details the characteristics, treatment methods, and outcomes of colorectal cancer patients who received initial treatment in 2015 at facilities participating in the JSCCR. These data should be helpful for patients to understand their disease accurately and for healthcare professionals to explain colorectal cancer and its treatments to patients.

Conflicts of Interest

There are no conflicts of interest.

Author Contributions

Study design, analysis and draft: HK

Interpretation of data: MA, MI, SI, MI, YK, KK, and HM

Critical review: KS and YA

Approval by Institutional Review Board (IRB)

Japanese Society for Cancer of the Colon and Rectum (93-1)

Teikyo University (20-246)

Disclaimer

Soichiro Ishihara is the Editor-in-Chief and Masafumi Inomata is one of the Associate Editors of Journal of the Anus, Rectum and Colon and on the journal's Editorial Board. They were not involved in the editorial evaluation or decision to accept this article for publication at all.