Hiroharu Isomoto

An index for estimating the probability of lymph node metastasis in rectal cancers. Lymph node metastasis and the histopathology of actively invasive regions of cancer

We examined resected specimens from 40 cases of advanced rectal cancer to determine the extent of microtubular cancer nests and undifferentiated cancer cells (budding). We investigated the relationship between this budding and lymphatic invasion (ly), venous invasion (v), and lymph node metastasis (n), respectively. Moreover, we examined the relationship between ly, budding, and n in the preoperative biopsy specimens of 112 patients, including those of the 40 cases mentioned above. The degree of budding, which was abundant in the actively in asive region, showed a strong correlation with the degree of ly and the existence of n in the resected specimens. Also, budding was recognized in a relatively large portion of the biopsy specimens (52 of 112 [46.4%]) and lymph node metastasis was found in 41 of 52 specimens (78.8%). In 57 specimens, neither ly nor budding was found, and 16 of these specimens (28.1%) had positive lymph nodes. These results implied that the degree of budding in the actively invasive region can be a great help in predicting the presence of n. The presence or absence of budding in preoperative biopsy specimens also can be an important factor (along with the degree of differentiation and ly) in estimating the probability of n.

Surgical treatment for patients with pulmonary metastases after resection of primary colorectal carcinoma.

Background. The optimum treatment for patients with pulmonary metastases from colorectal carcinoma is still controversial.

Evaluation of endorectal ultrasound for the assessment of wall invasion of rectal cancer. Report of a case.

To accurately assess the depth of cancer invasion, endorectal ultrasound was performed using a radial scanner (Aloka, 7.5 MHz) in 145 patients with rectal cancer. High-resolution ultrasound clearly depicted five- or seven-layer echographic structures in the normal rectal wall, and demonstrated cancer as a hypoechoic lesion. These layer structures provided an important feature in determining the depth of cancer invasion. Rectal cancers of 122 patients were examined thoroughly by endorectal ultrasound. In 95 of these patients (77.9 percent), ultrasonic assessment of the depth of cancer invasion as classified in four groups was correct, corresponding accurately to the microscopic findings. Ultrasonography overestimated the depth of cancer invasion in 21 patients, however, and underestimated it in six patients. This study indicated that a cause of the overestimation was inflammatory cell infiltration around cancer, and that one possible cause of underestimation was microscopically minimal invasion of cancer. Although there are certain limitations of endorectal ultrasound, this ultrasound technique will provide valuable information to determine the preoperative staging of rectal cancer.

Prognostic Evaluation of Perineural Invasion in Rectal Cancer

To evaluate whether perineural invasion (PNI) is an important prognostic factor in patients with rectal cancer, we reviewed the records of 373 patients who underwent curative surgery. Thirty-seven patients (9.9%) were identified as having tumors with PNI. The incidence of PNI was significantly increased in lesions categorized as stage III by the International Union Against Cancer (UICC) system (20%). There was a significant difference in local recurrence between patients with stage III lesions with PNI and those with stage III lesions without PNI (p < 0.005). Also, patients with PNI of stage III lesions had a significantly lower 8-year survival rate (26.7%, p < 0.001). We conclude that PNI is an important factor influencing the prognosis of patients with stage III disease. PNI should be classified as a subgroup of the clinical stage.

Treatment of rectal carcinoid tumors

We investigated the treatment of 24 rectal carcinoid tumors from both the clinicopathologic and prognostic viewpoints. All tumors less than 2 cm in diameter had neither muscle layer invasion nor lymph node metastasis, except for an atypical carcinoid tumor that had both lymphatic permeation and intramural metastasis. One typical carcinoid tumor larger than 2 cm had both several lymphatic permeations and urinary bladder invasion. All cases had a good prognosis with no recurrence and no new metastases. For rectal carcinoid tumors less than 2 cm in diameter, local resection is sufficient, whereas radical operation is required for tumors larger than 2 cm in diameter. For atypical rectal carcinoid tumors, radical operation should be considered even if the diameter is less than 2 cm.

Detection of unrecognized liver metastases from colorectal cancers by routine use of operative ultrasonography

The importance of diagnosis and detection of liver metastases cannot be overemphasized for the treatment and prognosis of colorectal cancers. As a new diagnostic technique, operative ultrasonography has been performed during 33 operations for colorectal cancers including three operations for metachronous liver metastases. Of these, in five patients (15.2 percent) ultrasonography using 5- or 7.5-MHz instruments identified metastatic tumors that had not been diagnosed during preoperative imaging studies or at exploration. Most of these tumors were approximately 1 cm in size and nonpalpable. Cases of these five patients are presented in this report. High-resolution operative ultrasonography is considered to be a valuable method for detection of unrecognized metastatic tumors and for precise localization and spatial assessment of these hepatic lesions. Because it is safe, simple, and highly sensitive, the routine use of operative ultrasound is encouraged during surgery upon colorectal cancers for systematic screening of metastatic liver tumors.

Carcinomatous lymphatic permeation. Prognostic significance in patients with rectal carcinoma—A long term prospective study

Background. The question of whether lymphatic permeation in rectal carcinoma is an index of prognosis remains controversial.

Primary linitis plastica carcinoma of the colon and rectum

Background. Linitis plastica carcinoma (LPC) usually shows a scirrhous growth pattern with a severe stromal desmoplastic reaction. Another growth pattern showing lymphangiosis carcinomatosa rather than scirrhous growth pattern, however, was noted. This study was designed to clarify the clinical and pathologic characteristics of colorectal LPC.

Clinical efficacy of video-assisted gasless transanal endoscopic microsurgery (TEM) for rectal carcinoid tumor

BackgroundWe used video-assisted gasless transanal endoscopic microsurgery (TEM) to evaluate 12 consecutive patients for carcinoid tumor with pathologically typical features in the proximal rectum. The study parameters included feasibility, results and final outcome.MethodsA scope with an optical angle of 25° and a 7-mm diameter was used for TEM. The carcinoid tumor was resected in full thickness. Primary closure was accomplished using a running suture of 3-0 braided absorbable suture.ResultsThe tumor in these patients was <15 mm in diameter. It was localized within the submucosal layer on the oral side from the peritoneal reflection and unreachable via Park’s transanal approach. The mean duration of the operation was 63 min. The postoperative course in all patients was free from significant complications, and all patients were discharged within 1 week. None of the patients had postoperative pain or required sedatives.ConclusionVideo-assisted gasless TEM is a simple and minimally invasive procedure to treat benign carcinoid tumors in the proximal rectum.

Small-cell carcinoma of the rectum

Three cases of small-cell carcinoma of the rectum are presented. Our conclusions are as follows: 1) small-cell carcinoma and carcinoid tumor of the rectum might have a common origin; 2) indications for surgical intervention for small-cell carcinoma of the rectum should be considered seriously; 3) small-cell carcinoma of the rectum should be classified as an aggressive type of rectal tumor that metastasizes easily to distant organs.