Pathological study of distal mesorectal cancer spread to determine a proper distal resection margin

Table 1 Site and frequency of cancer spread in mesorectum.

Site of spread	n	%
Proximal	3	14.3
Deep	5	23.8
Distal	1	4.8
Proximal+deep	5	23.8
Deep+distal	4	19
Proximal+deep+distal	3	14.3
Total	21	100

Table 2 Comparison of clinicopathologic characteristics between patients with and without in distal mesorectum (mean±SD, n, %).

Parameters	With involvement (n = 8)	Without involvement (n = 37 )	P value
Age, mean±SD (yr)	61.7±19.4	63.4±12.5	NS
Gender			NS
Male	6 (75.0)	23 (62.2)
Female	2 (25.0)	14 (37.8)
Tumor location1			NS
Anterior	2 (25.0)	13 (35.1)
Lateral	3 (37.5)	10 (27.0)
Posterior	1 (12.5)	7 (18.9)
Circumferential	2 (25.0)	7 (18.9)
Distance of tumor from dentate line (cm)			NS
≤5	5 (62.5)	26 (70.3)
> 5	3 (37.5)	11 (29.7)
Patterns of tumor growth			NS
Infiltrating	6 (75.0)	28 (75.7)
Pushing	0 (0.0)	4 (10.8)
Mixed	2 (25.0)	5 (13.5)
Tumor maximal diameter (cm)			NS
≤5	5 (62.5)	22 (59.5)
>5	3 (37.5)	15 (40.5)
Tumor differentiation			NS
Well	2 (25.0)	9 (24.3)
Moderate	3 (37.5)	21 (56.8)
Poor	3 (37.5)	7 (18.9)
TNM stage2			NS
I	0 (0.0)	6 (16.2)
II	0 (0.0)	11 (29.7)
III	7 (87.5)	17 (45.9)
IV	1 (12.5)	3 (8.1)
Depth of tumor invasion			NS
T1	0 (0.0)	3 (8.1)
T2	0 (0.0)	11 (29.7)
T3	7 (87.5)	21 (56.8)
T4	1 (12.5)	2 (5.4)
Lymph node metastasis			0.043
Present	7 (87.5)	15 (45.9)
Absent	1 (12.5)	22 (54.1)
Distant metastasis during follow up			NS
Present	1 (12.5)	1(2.7)
Absent	7 (87.5)	36 (97.3)

NS = not significant.

¹Confirmation of tumor location according to more than two-thirds of tumor area within any side of rectal wall.

²According to the American Joint Committee on Cancer Staging Manual[14].

Table 3 Mode of distal mesorectal and intramural spread of lower rectal cancer.

Number	Pattern ofgrowth	Tumor Differentiation	pTNMstage1	Layer ofspread	Mode ofspread	Maximum extentin situ (mm)	Distal resection Margin (mm)	Outcome after2.5 yr
1	Infiltrating	Poor	pT2N1M0	Mesorectum	LN	11	45	Disease free
2	Infiltrating	Poor	pT2N2M0	Submucosa	LN	8	33	Disease free
3	Mixed	Moderate	pT2N1M0	Mesorectum	LN	13	35	Local recurrence
4	Infiltrating	Moderate	pT3N2M0	MP	ly	10	40	Disease free
				Mesorectum	LN	25
5	Infiltrating	Moderate	pT2N0M0	Submucosa	D	7.5	40	Disease free
6	Infiltrating	Poor	pT3N1M0	Mesorectum	LN	36	38	Disease free
7	Mixed	Moderate	pT3N2M1	MP	D	5	25	Distant metastasis
				Mesorectum	LN	14
8	Infiltrating	Well	pT2N2M0	Mesorectum	ly	8	43	Disease free
9	Infiltrating	Moderate	pT2N0M0	Mesorectum	D	6	23	Disease free
10	Infiltrating	Moderate	pT3N2M0	MP	vi	4	28	Disease free
				Mesorectum	LN	9

¹According to the American Joint Committee on Cancer Staging Manual[14]; LN = lymph node metastasis; ly = lymphatic permeation; vi = vessel invasion; D = direct infiltration; MP = muscularis propria.

Table 4 Review of distal mesorectal spread of rectal cancer.

References	Cases (n)	With DMS (n)	Frequency of DMS (%)	Pattern of DMS	Maximum extent of DMS (cm)	Suggested DCM (cm)
Heald et al.[12]	-	5	-	ly, vi, LN	4	TME
Williams et al.[19]	50	3	6	LN	1.3	<5
Scott et al.[10]	20	4	20	ly, D	3	3 to 5
Shirouzu et al.[20]	610	44	7.2	ly, D, LN	≤2	1
Reynolds et al.[7]	50	12	24	LN, foci	5	TME
Hida et al.[21]	198	40	20.2	LN	4	2 cm (lower rectal cancer)
Tocci et al.[11]	53	19	35.1	LN, foci	-	TME
Ono et al.[5]	40	3	7.5	LN	2.4	3

DMS = distal mesorectal spread; DCM= distal resection margin; LN = lymph node metastasis; ly = lymphatic permeation; vi = vessel invasion; D = direct infiltration; foci = neoplastic microfoci.