Abstract:Background. Increased numbers of mast cells are found in various solid tumors. To investigate the role of mast cells in the vicinity of gastric cancer cells, we used special staining and an immunohistochemical technique. Methods. Specimens were surgically obtained from 102 patients with gastric cancer. Mast cells around the tumor edge of gastric cancer nests were counted by staining with 0.05% toluidine blue solution. Blood vessels in these areas were also counted, by immunohistochemical staining of endothelial cells for factor VIII. Results. The average number of mast cells and blood vessels in gastric cancer specimens was significantly higher than that in normal gastric tissue. Specimens from patients with advanced disease with metastases to lymph nodes had more mast cells than specimens from patients with early-stage disease. Mast cells in specimens from patients with metastatic lymph nodes were significantly increased in comparison with numbers in specimens from those without nodal metastases. Mast cell numbers in the specimens of patients with lymphatic or blood vessel invasion were significantly higher than numbers in specimens from patients without such invasion. Mast cells were localized near the new vessels around gastric cancer cells. Mast cell numbers increased as the number of blood vessels increased (correlation coefficient, 0.783). Postoperative survival curves revealed that patients with increased numbers of mast cells had a poor prognosis. Conclusions. All these results suggest that mast cell accumulation at the tumor site may lead to increased rates of tumor vascularization and, consequently, increased rates of tumor growth and metastasis.

Generally, LN metastases are seen in a small percentage of patients with early gastric cancer with mucosal or submucosal invasion [7]. In recent years, the technique of laparoscopy-assisted distal gastrectomy (LADG) with regional LN dissection has been developed and employed for early gastric cancer [8]. In March, 1997, we began to perform LADG as a minimally invasive surgery for early gastric cancer. However, the feasibility of LADG for early gastric cancer and the associated clinical outcome of patients who undergo LADG for early gastric cancer remain unclear.We therefore conducted a review of patients who underwent LADG for early gastric cancer, in an effort to compare the operative times, intra-operative blood loss, number of removed lymph nodes, postoperative recovery, and morbidity and mortality rates of LADG and conventional open distal gastrectomy (ODG). Our research was aimed at determining whether the laparoscopic procedure of LADG for early gastric cancer is really safe and minimally invasive, and whether or not the LADG improves quality of life, compared with ODG. Patients and methods PatientsThe patients were preoperatively diagnosed as having an early gastric cancer located in the lower or middle third of the stomach, from the results of endoscopy, endoscopic ultrasonography (EUS), and examination of biopsy specimens. The indications for LADG were that: (1) the tumor was located in the middle or lower part of the stomach, (2) the invasion of the tumor was limited to the mucosal layer or the submucosal layers (SM1). Results. The clinical and pathological backgrounds of the patients in the two groups were similar. The duration of surgery was not significantly different between the two groups, but the blood loss in the LADG group was significantly less than that in the ODG group. The number of removed lymph nodes was not significantly different between the two groups. The times to the first passing of flatus, first walking, and the restarting of oral intake; the length of hospital stay; and the duration of epidural analgesia were significantly shorter in the LADG group. The morbidity rate in the LADG group was lower than that in the ODG group. Conclusions. LADG is a safe and minimally invasive surgical technique, after which we can expect a faster recovery.

p21/Cip1/Waf1 (wild-type p53 activated fragment 1/cyclin-dependent kinase [Cdk]-interacting protein 1) is a prominent Cdk inhibitor and has been shown to be a downstream mediator of p53. In this study, we sought to clarify the clinical significance of Waf1 and the relationship between Waf1 and p53 in breast cancer. For this purpose, the expressions of Waf1 and p53 were evaluated immunohistochemically in a series of 104 patients. Waf1 was expressed in 51 (49%) of 104 tumors tested, and p53 in 33 tumors (32%). Inverse expression of these two proteins was seen in 76 cases (73%); 47 were Waf1-positive and p53-negative, and 29 were Waf1-negative and p53-positive. A comparison with clinicopathologic parameters showed that Waf1 expression correlated with negative lymph nodes (P<.01), a low histologic grade (P<.0001), and positive estrogen receptor status (P<.01). Recurrence-free survival was lower for patients with Waf1-negative tumors than for those with Waf1-positive tumors (P<.0001). In multivariate analysis, Waf1 expression and low histologic grade (1 or 2) tumors had an independent prognostic significance for recurrence-free survival. These results suggest that Waf1 is induced mainly by a p53-dependent pathway and could be a reliable indicator of recurrence in breast cancer.

In a series of 45 poorly differentiated adenocarcinomas (por) and 7 signet‐ring‐cell carcinomas (sig) of the colorectum, K‐ras gene mutation, p53 immunostaining and microsatellite instability (MSI) were analyzed for a comparison with 46 cases of colorectal carcinomas of the well or moderately differentiated type (well/mod). In addition, the mutations of simple repeated sequences in the transforming‐growth‐factor‐β type‐II receptor (T β R‐II) gene and the BAX gene were analyzed as possible targets for DNA replication errors. Mutation of the K‐ras gene in the por, sig and well/mod specimens was detected in, respectively, 22%, 11% and 48%, positive immunostaining for p53 in 41.8%, 28.6% and 60.3%, and MSI in 36%, 30% and 4%. Frameshift mutation of the T β R‐II gene was detected in 27.5% of the por and none of the sig specimens, while corresponding figures for mutation of the BAX gene were 15.7% and 0%. Significant differences between the por and well/mod tumors were found in the occurrence of K‐ras mutation at codons 12 and 13, and MSI. Clinicopathologically, the tumor status of por with MSI was found to significantly correlate with the tumor's location in the proximal colon. In cases without MSI and sig, no frameshift mutation of either the T β R‐II or the BAX gene was found. These results suggest that poorly differentiated and signet‐ring‐cell carcinomas have a genetic background different from that of well or moderately differentiated carcinomas of the colorectum, and that DNA‐replication error is at least partly involved in the carcinogenesis of these specific types of colorectal carcinomas. Int. J. Cancer (Pred. Oncol.) 84:33–38, 1999. © 1999 Wiley‐Liss, Inc.

Immunohistochemical staining for the p53 protein was performed in microwave-fixed, paraffin-embedded sections of normal, premalignant and malignant tissues of the female genital tract using a monoclonal antibody, PAb 1801. No staining was detected in normal and premalignant tissues, whereas nuclear staining of cancer cells was observed in 12 (22%) of 55 cervical squamous cell carcinomas, 4 (25%) of 16 cervical adenocarcinomas, 37 (42%) of 88 endometrial carcinomas, 23 (38%) of 60 ovarian adenocarcinomas, and 6 (100%) of 6 squamous cell carcinomas arising in dermoid cysts. Of interest, 1 of 7 endometrial cancers with concomitant atypical hyperplasia showed weak nuclear staining in a few atypical hyperplastic glands in addition to the cancerous lesions. Although staining was associated with cancers having a high histologic grade and serous papillary adenocarcinomas of the endometrium, it did not correlate with invasion, metastasis, or clinical stage. Comparison of the staining patterns with molecular analysis of mutations in the p53 gene showed the expected correlation of nuclear staining with missense mutations but not with nonsense mutations, which consistuted one third of all mutations found in this series. In addition, cytoplasmic staining did not predict mutation.

Recent studies have shown that the cyclin-dependent kinase (CDK) inhibitor p27^Kip1 represents an indicator for patients’ outcome in several human malignancies including gastric cancer. However, the clinicopathologic value of another class of CDK inhibitor, p16^INK4, has not been determined. In a retrospective study, we examined the expression of p16^INK4 by immunohistochemical assay of 80 samples of primary gastric cancers and their adjacent nonneoplastic mucosas. Less than 10% of non-tumor gastric mucosal cells were p16^INK4 positive, whereas the expression of p16^INK4 in gastric cancer cells varied widely from 0 to 100% (mean, 24.5%). The expression of p16^INK4 was not seen in 11.3% (9/80) of the cancer cases, but in 65% (52/80) this protein was even overexpressed when compared with the nonneoplastic mucosa. A clinicopathologic survey indicated that a low or no expression of p16^INK4 was associated with poorly differentiated carcinoma (p = 0.0133), but the level of expression did not correlate with other parameters including patients’ prognosis or with the expression of the pRb protein. In an effort to explore the underlying mechanism for the p16^INK4-negative cases, a prospective study was also performed on 20 cases of gastric cancer to compare the level of the p16^INK4 protein with the methylation status of the p16^INK4 promoter. Gastric cancer tissues with methylation expressed significantly lower levels of the p16^INK4 protein (p = 0.0013) and two of them lacked p16^INK4 expression altogether, whereas all the cancer tissues without methylation expressed it. These findings suggest that the p16^INK4 protein may be associated with differentiation of gastric cancer tissues and that methylation of the p16^INK4 promoter may, in part, account for the loss of p16^INK4 expression.

The tumour suppressor gene product p53 is believed to play an important role in the progression of human malignant tumours through mutation and over-expression. Using a microwave oven heating method, we have detected over-expression of p53 in buffered-formalin fixed, paraffin-embedded sections of oesophageal carcinomas immunohistochemically and examined the relationship between the p53 over-expression and postoperative survival. Employing a monoclonal antibody (pAb1801), nuclear p53 was detected in 56 of 105 (53%) tumour specimens. Homogeneous, heterogeneous, and focal immunostaining patterns were noted. No immunostaining was found in adjacent benign tissues. The results in buffered-formalin fixed sections were similar to those in the frozen sections. The cumulative survival rate of patients with p53 expression was significantly lower than that of the patients without expression (P < 0.05), even though there were no significant differences between the clinicopathological features of the two groups. The results indicate that the nuclear accumulation of p53 might be an independent prognostic factor in patients with oesophageal squamous cell carcinomas.

The results of this study suggest that absorbable clips are as safe and effective as standard metal clips for vessel and duct ligation in LC.