To inhibit local recurrence, it is very important to ensure a sufficient circumferential resection margin (CRM). Consequently, total pelvic exenteration1 is the standard procedure performed for patients with locally advanced rectal cancer. Recently, intraoperative evaluations identified only localized involvement of the prostate. The combined radical retropelvic prostatectomy with bladder-sparing surgery is frequently reported to be without sacrificing survival.2,3 But the combined radical resection of the seminal vesicle alone has been less well studied, especially with regard to disease pathology. We evaluated disease pathology for combined radical resection of the seminal vesicle in the treatment of rectal cancer.

Materials and Methods

We enrolled 7 patients who had combined radical resection of the seminal vesicle for treatment of rectal cancer. We recruited patients from the Department of Gastroenterological Surgery, Aichi Cancer Center Hospital (Nagoya, Japan), from January 1990 to December 2001 (Table 1). In all patients, the tumor was located in the rectum, and a radical operation was performed. However, a pelvic total extirpation surgery case was excluded. In the 6 remaining patients, combined radical resection of the seminal vesicle was predetermined before the operation (Fig. 1); in only 1 case was the combined radical resection assessed intraoperatively. The combined, radical, bilateral resection of the seminal vesicle was done for the right seminal vesicle in 4 patients and the left seminal vesicle in 1 patient. In the same study period, 35 cases without resection were weighed.

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Table 1 Clinicopathologic findings

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There were no significant differences between combined radical resection cases and cases without resection in terms of patient age, maximum tumor size, macroscopic tumor configuration, histologic type, surgical procedure, and Dukes classification score.

The resected specimens were fixed with 10% formalin for several days, and the entire tumors were macroscopically sliced into 4-mm sections at the deepest part of the tumor containing tissue sample. Histopathologic diagnosis was made by hematoxylin and eosin stain in the usual manner, without specific immunostaining.

Using a microscope, we evaluated the CRM4—that is, the shortest distance between the deepest part of the cancer and the incisal surface—and the shortest distance between the deepest part of the cancer and the surface of seminal vesicle (Fig. 2).

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We also evaluated the “tumor deposit” in fat tissue surrounding the excised specimen, that is, the carcinomatous clumped tissue that was continuous with the main tumor, including lymphatic or vascular invasions (Fig. 3).4 But the worldwide consensus on the definition of “tumor deposit” was made as a decision.5 Ueno et al6 advocated “extramural cancer deposits” that differ in structure from lymph nodes. Ishikawa et al7 defined “extranodal cancer deposits” as small cancers in the fatty tissue outside the colon or rectum and in the detached fatty tissue around the dissected lymph nodes. Here, we defined a positive finding as one in which the “tumor deposit” was present less than 1000 µm from the incisal surface.

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We sought to determine the local recurrence rate between patients undergoing combined radical resection of the seminal vesicle and patients without resection.

All data are expressed as mean (±SD). Statistical analysis was performed using the χ² test or Fisher exact probability text, or Student t test or Mann-Whitney U test. Multivariate stepwise logistic regression analysis was subsequently performed to identify factors that were considered to have an influence on lymph node metastasis. Statistical significance was set at P < 0.05.

Results

Among combined radical resection cases of the seminal vesicle, no histopathologic invasion to the seminal vesicle was found. Denonvilliers fascia was not destroyed in all cases.

The average CRM distance was 5.97 mm (range, 0.48–16.08 mm) among the combined radical resection cases, which was significantly longer than the distance in cases without resection (P < 0.001). The CRM of the combined radical resection cases was significantly longer than the distance between the seminal vesicle and the surface of the cancer (P  =  0.038; Table 2).

Table 2 The average CRM distance and the distances between seminal vesicle and the surface of cancer^a

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There were no tumor deposits in the combined radical resection cases, but 7 cases were found in the group without resection (Table 3).

Table 3 “Tumor deposits” in the specimen

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Disease recurrence was seen in 2 cases (28.6%) in the combined radical resection group and in 17 cases (33.7%) in the group without resection. Local recurrence was not seen among combined radical resection cases; it was seen in 3 cases (5.9%) without resection (Table 4).

Table 4 Disease recurrence in the combined radical resection group and in the group without resection

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Discussion

The CRM of surgical specimens has evolved as an important prognostic factor in cases of rectal cancer.4,8 Previously, cases that had a distance of 1 mm or less were taken as CRM involvement in the tumor, and local recurrence was well recognized.9,10 Recently, it was reported that a CRM smaller than 2 mm is associated with a poor prognosis and that such patients should receive neoadjuvant therapy.8,11

But so far only the distance of the resection margin was investigated, and this was done without an anatomic study. In particular, where the main tumor is located on the anterior wall of the rectum, it is important to be aware of the relationship among seminal vesicle, Denonvilliers fascia, and the main tumor. Denonvilliers fascia lies posterior to the prostate and seminal vesicles and anterior to the extraperitoneal rectal wall, anterior mesorectum, and fascia propria.12–14

To date, histopathologic studies about operative, local, far-advanced rectal cancer, such as total pelvic resection or prostatectomy,1,2 have been frequently discussed. In these specimens, Denonvilliers fascia that was destroyed by local, far-advanced rectal cancers or by recurrent colorectal cancer was almost completely recognizable, and consequently the earlier phases of the histopathologic mode of invading Denonvilliers fascia were not well understood. But our study indicates that no histopathologic invasion into the seminal vesicle was found, and Denonvilliers fascia was not destroyed in all combined radical resection cases, despite identification of invasion on gross findings during surgery. Our histologic study gives the first detailed description of the therapeutic effectiveness of combined radical resection of the seminal vesicle in the treatment of rectal cancer in the light of Denonvilliers fascia.

The pathologic finding that a tumor deposit was not found inside the seminal vesicle suggested that Denonvilliers fascia has the potential to protect against the invasion of rectal cancer. Similarly, Kinugasa et al15 reported that Denonvilliers fascia prevented invasion.

Accordingly, the combined radical resection of the seminal vesicle ensures the full-thickness excision of Denonvilliers fascia, whereas the combined radical resection of the seminal vesicle in the treatment of rectal cancer ensures a sufficiently large CRM and attenuates local recurrence.