Functional colonic obstruction in an adult as a presenting feature of thymoma.

Functional colonic obstruction is a colonic motility disorder with a number of causes. One cause is myenteric ganglionitis, which may result from paraneoplastic processes. We present the case of a previously healthy 53-year-old man who presented with a week's history of functional colonic obstruction. A transverse loop colostomy failed to resolve his symptoms and he subsequently underwent an extended right hemicolectomy. Histology demonstrated lymphocytic myenteric ganglionitis that was felt to be of paraneoplastic origin. The patient later developed bilateral ptosis and was diagnosed with ocular myasthenia gravis. Further investigation revealed the presence of a thymoma that was resected, resulting in an improvement to his symptoms. We present this case and a review of the literature to illustrate the importance of seeking out a paraneoplastic cause for functional colonic obstruction in adults as early resection of the tumour may help alleviate symptoms and avoid bowel surgery.

DNA markers predicting benefit from adjuvant fluorouracil in patients with colon cancer: a molecular study.

BACKGROUND: Present clinical algorithms assign adjuvant chemotherapy according to prognosis, but clinical decision-making would be greatly improved if reliable predictive markers were available to identify which subsets of patients benefit most from treatment. We examined molecular markers in preserved tissue from patients with Dukes' B or C colon cancer randomised to receive, or not, adjuvant fluorouracil, and assessed each marker's prognostic and predictive value. METHODS: Formalin-fixed paraffin-embedded paired normal and tumour samples were obtained from 393 patients with colon cancer from the UK AXIS trial of postoperative portal vein infusion fluorouracil versus control. We measured loss of heterozygosity (LOH) and microsatellite instability at four loci: P53 (17p13), D18S61 (18q22.3), D18S851 (18q21.1), and DP1 (5q21). The prognostic value of each marker was assessed with the log-rank test, and the predictive value by comparison of treatment hazard ratios with the chi(2) test for heterogeneity (CSH). FINDINGS: In 228 (58%) patients informative for LOH at D18S61, this marker was significantly predictive: benefit from fluorouracil was significantly greater in patients retaining heterozygosity than in those with LOH (CSH p=0.02). Conversely, LOH at D18S61 was a significant prognostic marker of improved outcome in untreated patients. 314 (80%) patients were informative for LOH at at least one of the three 17p and 18q sites, of whom half retained heterozygosity at one or more site. The effect of chemotherapy in these patients was striking (hazard ratio 0.45, 95% CI 0.28-0.73), whereas chemotherapy had no effect in patients with no retained heterozygosity (0.91; 0.56-1.48), CSH p=0.039. INTERPRETATION: Retention of heterozygosity at one or more 17p or 18q sites was associated with the ability to benefit from adjuvant fluorouracil. These results support the principle of developing molecular markers as predictive factors in treatment decisions.

Specific patterns of chromosomal abnormalities are associated with RER status in sporadic colorectal cancer.

Current opinion of the genetic events driving colorectal tumourigenesis focuses on genomic instability. At least two apparently independent mechanisms are recognized, microsatellite instability and chromosomal instability. The genetic defects underlying each type of instability are only partially understood and controversy remains as to the role of p53 in the generation of chromosomal defects in colorectal cancer. This study sought to clarify the relationships between chromosomal abnormalities and defects of both p53 and mismatch repair. Extensive chromosomal analysis was undertaken, using flow cytometry and comparative genomic hybridization, of a series of sporadic colorectal cancers which had been grown to early passage as subcutaneous xenografts in SCID mice. Overall levels of chromosomal defects were observed to be low in RER+ cancers compared with RER- and distinctive patterns of chromosomal anomalies were found to be associated with both the RER+ and RER- phenotype. No particular level or pattern of chromosomal anomalies appeared to be associated with p53 status, supporting recent observations that abnormal p53 function is not sufficient to cause chromosomal anomalies in colorectal tumours.

Role of BAX mutations in mismatch repair-deficient colorectal carcinogenesis.

BAX gene mutations occur in approximately 50% of RER+ colorectal cancers. To determine the role of these mutations in tumour progression we analysed multiple different tumour sites from RER+ colorectal cancers for BAX mutations. Sixty colorectal carcinomas were analysed for microsatellite instability at loci BAT-26, L-myc, TGF betaRII, D13S160 and D2S123. Twelve out of 60 tumours (20%) were RER+. Forty-five different tumour sites from the 12 RER+ carcinomas were analysed for BAX mutations at the [(G)8] tract in exon 3. Six out of 12 (50%) RER+ tumours showed BAX mutations, four of which showed a homogenous pattern of such mutations detected in all tumour sites. In the other two cases, BAX mutations were present in some but not all tumour sites sampled from the same patient. In contrast, TGF betaRII mutations were found in 9/12 cases (75%) and in each of these were present in all the sampled sites. Two cases showed neither BAX nor TGF betaRII mutation. These data suggest that mutations in TGF betaRII may occur at a very early stage in tumour progression, perhaps in the founder clone. BAX mutations, however, are clearly not necessary for formation of the founder clone and can occur for the first time later in tumour progression.

Heterogeneity studies identify a subset of sporadic colorectal cancers without evidence for chromosomal or microsatellite instability.

Two apparently independent mechanisms of instability are recognized in colorectal cancer, microsatellite instability and chromosomal instability. Evidence from colorectal cancer cell lines indicates the presence of either, or both, types of instability in the vast majority. Here, we sought to determine the prevalence of such instability in primary sporadic colorectal cancers. Microsatellite instability was established by demonstration of ovel clonal, nongerm-line alleles in at least two of four tested loci. Chromosomal abnormalities were identified by comparative genomic hybridization (CGH) and flow cytometric analysis of nuclear DNA content. Tumours harbouring chromosomal instability were distinguished from those with stable but aneuploid karyotypes by comparing chromosomal defects at multiple sites throughout each cancer. This analysis allowed assessment of both the number of chromosomal abnormalities and their heterogeneity throughout the tumour. The results confirm that microsatellite instability is consistently associated with multiple, repeated changes in microsatellites throughout the growth of the affected colorectal carcinomas. There were also several carcinomas in which major structural or numerical abnormalities in chromosomes had clearly continued to arise during tumour growth. However, a substantial subset of tumours showed neither microsatellite instability nor multiple, major chromosomal abnormalities. We suggest that the development of a proportion of colorectal cancers proceeds via a different pathway of carcinogenesis not associated with either of the currently recognized forms of genomic instability.

The diagnostic value of cytomorphological traits in low and high risk type HPV infections.

The purpose of the study was to establish the diagnostic value of cytomorphological traits present in cervical smears in determining HPV infection. We examined 528 women, most of them between 18 and 34 years of age and sexually active, for the prevalence of HPV infection and compared the results of HPV DNA detection with the presence of cytomorphological traits of HPV infection in their cervical smears. The Digene Hybride Capture System technique was employed to detect HPV DNA in cytological material; cervical smears were examined by an experienced pathologist, who did not have prior knowledge of the HPV DNA test results. None of the cytomorphological traits examined proved to be pathognomonic for HPV infection. The diagnosis of HPV infection cannot be determined with certainty by a routine cytological examination. Only 15% of cervical smears from women infected with HPV showed classic cytomorphological traits of HPV infection - koilocytosis and/or dyskeratosis. We conclude that if more than three non-classic traits of HPV infection are found in a cervical smear, HPV infection can be suspected.