The p53 gene in patients under the age of 40 with gastric cancer: mutation rates are low but are associated with a cardiac location.

BACKGROUND: Determining both the frequency and the spectrum of p53 gene mutation in young patients with gastric cancer might provide clues to the host related genetic mechanism(s) in gastric carcinogenesis. PATIENTS AND METHODS: p53 mutations were assessed (by means of polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP), followed by DNA sequencing) in a cohort of 105 consecutive Italian patients in whom gastric cancer was ascertained before the age of 41. RESULTS: A low prevalence of p53 mutations (eight of 105) was observed, with no significant difference between intestinal (three of 31; 10%) and diffuse (five of 74; 7%) phenotypes. A significantly higher prevalence of p53 mutations was associated with the cardiac location (odds ratio, 7.09; confidence interval, 1.56 to 32.11). In all but one case, p53 mutations were associated with a stage higher than I. All eight mutations were located at CpG sites, where G : C to A : T transitions have been associated with frequent methylation at the C5 position of cytosine. CONCLUSIONS: These findings show that, unlike what has been consistently demonstrated in the general population, p53 mutations are uncommon in gastric cancer occurring in young patients, and in such patients, p53 alterations are significantly associated with the cardiac location.

Oesophageal resection for high-grade dysplasia in Barrett's oesophagus.

BACKGROUND: The aims of this study were to evaluate the prevalence of invasive cancer in patients with high-grade dysplasia in Barrett's oesophagus and to verify whether a second endoscopy with multiple biopsies could improve the accuracy of preoperative diagnosis. In addition, the mortality, morbidity and survival rates in patients with high-grade dysplasia having oesophageal resection were recorded. METHODS: Fifteen patients were observed from 1982 to 1998; the first seven patients were offered primary oesophageal resection after diagnosis. The other eight patients underwent a second endoscopy with a median of 12 biopsies examined. All later underwent oesophageal resection. RESULTS: Invasive adenocarcinoma was found in five patients, with a minimal difference between the first and second periods (two of seven versus three of eight). There were no perioperative deaths. Early morbidity was observed in eight patients and late morbidity in four. The actuarial survival rate was 79 per cent at 5 years. The Karnofsky status was unchanged from preoperative values in 13 of 15 patients after a median follow-up of 46 months. CONCLUSION: These patients with high-grade dysplasia had a 33 per cent probability of harbouring invasive oesophageal carcinoma but even a second endoscopy failed to identify patients with invasive tumour. Oesophagectomy was performed with no deaths and remains a rational treatment in patients fit for surgery.

Microsatellite instability and/or loss of heterozygosity in young gastric cancer patients in Italy.

Gastric cancers are rarely diagnosed before the age of 40 years and the incidence reaches a peak during the 7th decade in the general population. A molecular mechanism of early tumor onset may be determined by comparing microsatellite instability (MSI), indicative of error-prone mismatch repair, and loss of heterozygosity (LOH) between gastric cancers in patients < or = 40 years of age and those of older ages. Three to 5 chromosomal loci, where MSI and/or LOH are commonly found in gastric cancers in the general population, were examined in formalin-fixed, paraffin-embedded samples from 102 patients < or = 40 years of age using a polymerase chain reaction-based non-radioactive screening method. MSI and/or LOH at a minimum of 1 locus were detected in 11/102 patients. The frequency of MSI and/or LOH at the D11S904 locus was significantly higher than that at the D2S119, D2S123, D5S409 and IFNA regions. No preferential genetic changes at the D11S904 locus were observed in elderly patients. Among several clinicopathological variables, a statistically significant association with MSI and/or LOH was observed only for tumors located at the cardia, compared with tumors at the antrum and the corpus. Our findings suggest that a unique mechanism may be involved in increasing the susceptibility of the D11S904 locus for either MSI or LOH, especially for cardia tumors in young patients. Early onset of gastric cancers in patients < or = 40 years of age is associated with genetic changes at preferential chromosomal loci, including D11S904.

p16/CDKN2 alterations and pRb expression in oesophageal squamous carcinoma.

BACKGROUND: Upregulation of the cell cycle associated genes, p16/CDKN2 and the retinoblastoma susceptibility gene (Rb), is commonly seen during the proliferation of normal cells. An inverse relation between the expression of p16/CDKN2 and Rb has been noted in many tumours, but has not yet been determined in oesophageal squamous carcinoma. AIMS: To investigate p16/CDKN2 genetic alterations and both the p16/CDKN2 and the Rb protein (pRb) immunophenotypes in oesophageal squamous carcinoma. METHODS: Twenty primary oesophageal squamous carcinomas were examined for mutations in p16/CDKN2 by the polymerase chain reaction, single stranded conformational polymorphism, and DNA sequencing. Synthesis of p16/CDKN2 and pRb proteins was determined by immunohistochemistry in 19 specimens of formalin fixed, paraffin wax embedded tissues. RESULTS: Mutations of p16/CDKN2 were not detected in exons 1 and 2. In only one case, G to C and C to T base changes were detected in a non-coding region of exon 3. Expression of p16/CDKN2 and Rb was observed in both normal and neoplastic areas of tissue sections, indicating neither consistent homozygous deletion nor consistent hypermethylation of the genes in tumours. Fourteen tumours showed an inverse expression of p16/CDKN2 and Rb. An increased percentage of cells that immunostained positively for p16/CDKN2 but not for pRb was observed in eight tumours, five of which had no detectable pRb, suggesting defective Rb expression in these oesophageal squamous carcinomas. CONCLUSIONS: These results indicate that p16/CDKN2 mutations occur infrequently in oesophageal squamous carcinoma. The alteration of the Rb gene is suggested as an important step in the development of these tumours.

p53 alterations but no human papillomavirus infection in preinvasive and advanced squamous esophageal cancer in Italy.

Geographic differences in exposure to suspected carcinogens have been identified in esophageal carcinogenesis, and both p53 alterations and human papillomavirus (HPV) infection have been reported in esophageal squamous carcinoma (ESC) from high-risk areas, including China and South Africa. The status of p53 alterations and HPV infection in ESC has not been determined in northern Italy, where the incidence of ESC is low. Formalin-fixed paraffin-embedded esophageal samples containing normal, dysplastic, and carcinomatous tissue from 18 patients were examined for p53 protein accumulation with immunohistochemistry, p53 mutation (exons 5-8) with PCR-single-strand conformation polymorphism analysis and DNA sequencing, and HPV infection with PCR using general primers to amplify the L1 gene. Accumulation of p53 protein was observed in both precancerous and carcinomatous lesions. p53 mutations were rare in dysplastic lesions but were detected in 9 of 18 carcinomas, a finding consistent with reports from other geographic areas. Examination of the p53 mutation spectrum revealed no hot spot mutation. In contrast, HPV was not found in any of these 18 cases. This is consistent with the findings from other low ESC risk areas in which HPV infection may not play a crucial role in esophageal oncogenesis, whereas the high risk of ESC in China and South Africa may be attributed to frequent HPV infection.

bcl-2 and p53 immunophenotypes in pre-invasive, early and advanced oesophageal squamous cancer.

AIMS: An inverse correlation between bcl-2 and p53 expression has been reported in several types of epithelial tumour. The role of bcl-2 and p53 in the development of oesophageal squamous carcinoma has yet to be established. The expression of bcl-2 and p53 proteins has been evaluated in the multistage oesophageal tumorigenesis, which progresses from normal mucosa to dysplasia (squamous intraepithelial lesion, SIL), to invasive early and advanced oesophageal squamous cancer. METHODS AND RESULTS: Sixty-four cases of squamous oesophageal cancer, coexisting with SIL in 18 cases, were immunohistochemically analysed for any overexpression of bcl-2 and p53 proteins. Any association of bcl-2 and p53 protein expression with patient survival was also analysed. We observed bcl-2 expression that decreased significantly during the progression of oesophageal carcinogenesis. A decreasing frequency in the expression of bcl-2 in advanced oesophageal squamous cancer coincided with frequent p53 overexpression. bcl-2 expression was correlated with patient survival by univariate analysis. The association disappeared after adjusting for tumour stage, p53 overexpression showed no association with patient survival by either univariate or multivariate analysis. CONCLUSIONS: The down-regulation of bcl-2 and upregulation of p53 in advanced oesophageal squamous cancer suggest that bcl-2 and p53 proteins may interact in the progression of oesophageal squamous cancer.

p53 overexpression in the multistep process of esophageal carcinogenesis.

The timing of p53 mutation in the multistep process of esophageal carcinogenesis is still under debate. We tested p53 expression in 16 samples of low-grade and 29 samples of high-grade esophageal dysplasia (ED) coexisting with esophageal squamous cancer (ESC) in 31 patients who underwent total esophagectomy. In normal mucosa, a positive immunoreaction was detected in 10 of 31 cases, always restricted to the lower half of the epithelial thickness. We detected p53-positive nuclei in 11 of 16, 23 of 29, and 23 of 31 samples of low-grade ED, high-grade ED, and ESC, respectively. Cases exhibiting positive staining in dysplastic samples also demonstrated positive immunoreaction in the carcinomatous tissue. Immunoreactivity in cancer cells was never found in the absence of positive dysplastic nuclei. A significantly higher score of immunoreactive nuclei was detected in high-grade versus low-grade and in low-grade compared with normal mucosa. These data suggest that p53 mutation may represent an early event in esophageal oncogenesis.