Mutation screening of mismatch repair gene Mlh3 in familial esophageal cancer.

AIM: To shed light on the possible role of mismatch repair gene Mlh3 in familial esophageal cancer (FEC). METHODS: A total of 66 members from 10 families suggestive of a genetic predisposition to hereditary esophageal cancer were screened for germline mutations in Mlh3 with denaturing high performance liquid chromatography (DHPLC), a newly developed method of comparative sequencing based on heteroduplex detection. For all samples exhibiting abnormal DHPLC profiles, sequence changes were evaluated by cycle sequencing. For any mutation in family members, we conducted a segregation study to compare its prevalence in sporadic esophageal cancer patients and normal controls. RESULTS: Exons of Mlh3 in all samples were successfully examined. Overall, 4 missense mutations and 3 polymorphisms were identified in 4 families. Mlh3 missense mutations in families 9 and 10 might be pathogenic, but had a reduced penetrance. While in families 1 and 7, there was no sufficient evidence supporting the monogenic explanations of esophageal cancers in families. The mutations were found in 33% of high-risk families and 50% of low-risk families. CONCLUSION: Mlh3 is a high risk gene with a reduced penetrance in some families. However, it acts as a low risk gene for esophageal cancer in most families. Mutations of Mlh3 may work together with other genes in an accumulated manner and result in an increased risk of esophageal tumor. DHPLC is a robust and sensitive technique for screening gene mutations.

Surgery for young patients with lung cancer.

OBJECTIVES: To investigate the relationship between the clinical features and prognosis in young patients with lung cancer who underwent resection. METHODS: Statistical analysis was employed on sex, age, symptoms, diagnosis, treatment and prognosis, in 92 young cases younger than 40 years old among 930 cases with primary lung cancer who underwent surgery from January 1978 to December 1996. RESULTS: There were 92 young patients with lung cancer, accounting for 9.89% of the total cases. They were 71 male and 21 female patients, with the ratio of 3.38:1. The histological types were 34 squamous cell carcinomas (37%), 30 adenocarcinomas (33%), 26 small cell carcinomas (28%), and two large cell carcinomas (2%). On TNM staging, there were 30 cases in stage I (32.6%), 30 in stage II (32.6%) and 32 in stage III (34.8%). Lobectomy was conducted in 54 patients (59%), pneumonectomy in 36 (39%) and wedge-shaped resection in two cases (2%). The rate of pneumonectomy in young patients was significantly higher than that of 18% in older patients (>40) with lung cancer (P<0.01). 57 patients (62%) received absolutely curative resection; 28 cases (30%), relatively curative resection; seven cases (8%), non-curative resection. The postoperative 5-year-survival was 46% (42/92), in comparison with 34% (288/838) in patients older than 40 receiving operation during the same period, with significant difference between the two groups (P<0.05). The 5-year-survivals in patients with squamous cell carcinoma, adenocarcinoma, small cell carcinoma and large cell carcinoma were 68% (23/34), 30% (9/30), 38% (10/26) and 0 (0/2), respectively. The survival in squamous cell cancer was markedly higher than in adenocarcinoma (P<0.01) and in small cell carcinoma (P<0.05). There was no significant difference between adenocarcinoma and small cell cancer. The 5-year-survivals in stage I, II and III were 63% (19/30), 53% (16/30) and 22% (7/32), respectively. There was no significant difference between stage I and II, while remarkable difference was found between stage I and III (P<0.01), and between stage II and III (P<0.05). The 5-year-survival in patients undergoing absolutely curative resection was 67% (38/57), and 14% (4/28) in patients with relatively curative resection, with significant difference (P<0.01). No patient survived longer than the 5th postoperative year in seven cases receiving non-curative resection. CONCLUSIONS: Young patients with lung cancer were more often seen in male than in female. Squamous cell carcinoma accounted for the most part, no statistical difference, however, compared with adenocarcinoma and small cell carcinoma. The pneumonectomy rate in young patients was remarkably higher than that in patients older than 40. The postoperative 5-year-survival in young patients was considerably higher than in patients older than 40 who underwent surgery during the same period. Favorable prognosis was seen in patients with squamous cell carcinoma and undergoing absolutely curative resection, while worse outcome in stage III cancer.