Exposed water ice on the nucleus of comet 67P/Churyumov-Gerasimenko.

Although water vapour is the main species observed in the coma of comet 67P/Churyumov-Gerasimenko and water is the major constituent of cometary nuclei, limited evidence for exposed water-ice regions on the surface of the nucleus has been found so far. The absence of large regions of exposed water ice seems a common finding on the surfaces of many of the comets observed so far. The nucleus of 67P/Churyumov-Gerasimenko appears to be fairly uniformly coated with dark, dehydrated, refractory and organic-rich material. Here we report the identification at infrared wavelengths of water ice on two debris falls in the Imhotep region of the nucleus. The ice has been exposed on the walls of elevated structures and at the base of the walls. A quantitative derivation of the abundance of ice in these regions indicates the presence of millimetre-sized pure water-ice grains, considerably larger than in all previous observations. Although micrometre-sized water-ice grains are the usual result of vapour recondensation in ice-free layers, the occurrence of millimetre-sized grains of pure ice as observed in the Imhotep debris falls is best explained by grain growth by vapour diffusion in ice-rich layers, or by sintering. As a consequence of these processes, the nucleus can develop an extended and complex coating in which the outer dehydrated crust is superimposed on layers enriched in water ice. The stratigraphy observed on 67P/Churyumov-Gerasimenko is therefore the result of evolutionary processes affecting the uppermost metres of the nucleus and does not necessarily require a global layering to have occurred at the time of the comet's formation.

Human autologous mixed lymphocyte reactivity is primarily specific for xenoprotein determinants adsorbed to antigen-presenting cells during rosette formation with sheep erythrocytes.

We present evidence that most T cells proliferating in response to autologous sheep erythrocyte (SRBC)-separated non-T cells (NT) cells are not specific for autoantigens but for antigens derived from xenogeneic sources. The conclusion was based on the following three observations. First, we found that NT cells isolated in the absence of xenoproteins by means of density gradient centrifugation on Percoll only weakly stimulated autologous T cells. Because this weak proliferation could not be expanded in restimulation experiments, its significance as an immune recognitive event remains questionable. NT cells isolated by the above method in the absence of xenogeneic determinants readily acquired stimulatory capacity after brief exposure to either SRBC or fetal calf serum. Second, restimulation of T memory cells generated in 1 degree autologous mixed lymphocyte reaction (AMLR) against SRBC-separated autologous NT cells was exclusively seen when NT cells exposed to or separated with xenoproteins were used for restimulation. Third, T memory cells generated against SRBC-separated autologous NT cells were specifically restimulated by autologous Percoll-separated NT cells that had been pulsed with a variety of xenogeneic mammalian sera. These xenogeneic determinants were preferentially recognized in context with autologous HLA-DR+ cells. From these findings and from our previous results that indicated an absolute requirement of HLA-DR+-adherent NT cells (8), we conclude that human AMLR primarily does not represent an autoantigen but a xenoantigen response that is genetically restricted by the HLA-DR type of the antigen-presenting cell.

Comet yanaka (1988r): a new class of carbon-poor comet.

As part of a program to determine the chemical composition of a sample population of comets, a very unusual comet, Yanaka (1988r), was observed in January 1989. Although the comet showed the usual emissions of Ol and NH(2), it did not display any hint of C(2) or CN emission. The comet is depleted in C(2) by at least a factor of 100 and in CN by a factor of 25 relative to typical comets. If comets originate from interstellar clouds, Yanaka (1988r) could be an interloper from a cloud of different composition. If Yanaka (1988r) was formed within our solar system, the solar nebula was less uniform than assumed by most present models of formation.

Deuterated methane observed on saturn.

Absorptions for the V(2) band of deuterated methane (CH(3)D) have been observed in the 5-micron spectrum of Saturn, obtained with a Fourier transform spectrometer. Analysis of the band yields a CH(3)D abundance of 2.6 +/- 0.8 centimeter-amagat and a temperature of 175 +/- 30 K for the mean level of spectroscopic line formation. This temperature indicates that a substantial portion of Saturn's flux at 5 microns is due to thermal radiation, and that we are therefore looking fairly deep into its atmosphere, as is the case for the Jupiter 5-micron window. This CH(3)D abundance leads to a deuteriumlhydrogen ratio of about 2 x 10(-5) in Saturn's atmosphere. This ratio is much lower than the terrestrial value but comparable to that determined for Jupiter and may be taken as representative of the deuteriumlhydrogen ratio in the solar system at the time of its formation.

Inhibition by alkyl-lysophospholipids of tritiated thymidine uptake in cells of human malignant urologic tumors.

Alkyl-lysophospholipids (ALP) inhibited the uptake of [3H]thymidine by cells from a variety of human urologic tumors in vitro. Cells of prostate carcinomas, a seminoma, various bladder carcinomas and teratocarcinomas showed proliferation rates that were 10% of those of the controls when incubated with some ALP for longer than 24 hours. Concentrations as low as 1 microgram ALP/ml medium (10(6) tumor cells) were effective. Antitumor action increased after incubation for 2-5 days. Morphologic studies showed tumor cell death after incubation periods of this length. Equivalent concentrations of conventional cytostatic drugs used in anticancer chemotherapy protocols did not cause greater inhibition of [3H]thymidine uptake by tumor cells in vitro. Human embryonic fibroblasts were not sensitive to ALP, whereas cytostatic drugs completely inhibited their proliferation at comparable doses.

Cytotoxicity of the alkyl-linked lipoidal amine 4-aminomethyl-1-[2,3-(di-n-decyloxy)-n-propyl]-4-phenylpiperidine (CP-46,665) in cells from human tumors and leukemias.

The alkyl-linked lipoidal amine 4-aminomethyl-1-[2,3-(di-n-decyloxy)-n-propyl]-4-phenylpiperidine (CP-46,665) inhibited the in vitro incorporation of tritiated thymidine into blasts of eight leukemias and cells of nine different solid tumors of human origin. This activity was well correlated with trypan blue dye exclusion, which was tested to assess cell membrane damage. Scanning electron microscopy revealed loss of cell surface features and severe cell membrane destruction after incubation with CP-46,665. These effects on thymidine uptake and single cell viability were accompanied by a clear loss of the reproductive capacities of human tumor and leukemic cells as measured in a human tumor stem cell assay after incubation with CP-46,665. The above-mentioned cytostatic and cytotoxic effects of CP-46,665 were dependent on dosage and incubation time. Destruction of leukemic blasts was often completed with greater than or equal to 5 micrograms/ml after an incubation of greater than or equal to 48 hr or greater than or equal to 10 micrograms/ml after an incubation of greater than or equal to 24 hr. Cells from solid tumors usually required a slightly higher drug concentration and longer incubation period for maximum killing. The alkyl-linked lipoidal amine CP-46,665 often showed considerably greater efficacy than did the alkyl-linked phospholipid rac-1-O-octadecyl-2-O-methylglycero-3-phosphocholine tested in comparison. In contrast to both drugs, 2-lysophosphatidylcholine showed only minor activity within the same dose range.

Cytotoxicity of thioether-lysophospholipids in leukemias and tumors of human origin.

Thioether-lysophospholipids inhibited the in vitro incorporation of [3H]thymidine into blasts of 8 leukemias, lymphocytes of 3 chronic lymphocytic leukemias, and cells of 12 different solid tumors of human origin. This effect correlated with trypan blue dye exclusion, which was used to assess cell damage. Scanning electron microscopy revealed severe membrane destruction after incubation with thioether-lysophospholipids. Cytostatic and cytotoxic effects of thioether-lysophospholipids were dependent on dosage and incubation time. Destruction of leukemic blasts was completed with greater than or equal to 5 micrograms/ml after an incubation of greater than or equal to 48 hr, but 10 to 20 micrograms/ml were necessary in solid tumors. Ester-linked 2-lysophosphatidylcholine was ineffective in the same dose range, which points to the requirement of the alkyl moiety in SN1 of the molecule for the antineoplastic properties of lysophospholipid analogues.

Prognostic impact of urokinase-type plasminogen activator and its inhibitor PAI-1 in completely resected gastric cancer.

The prognostic impact of the proteolytic factors urokinase-type plasminogen activator (uPA) and plasminogen activator inhibitor type 1 (PAI-1) was evaluated in 76 completely resected gastric cancer patients enrolled in a prospective study. All patients underwent macroscopically and microscopically residual tumor-free resection (category R0, Union International Contre Cancer, 1987). uPA and PAI-1 levels were quantified in detergent-extracted (Triton X-100) specimens of primary gastric tumors by enzyme-linked immunosorbent assays. Median values of 1.57 ng uPA/mg protein were determined in tumor tissue extracts compared to 0.14 ng uPA/mg protein in normal mucosa. For PAI-1, 0.93 ng PAI-1/mg protein versus 0.09 ng PAI-1/mg protein was calculated. uPA levels in tumor tissue extracts were significantly correlated with vascular invasion, Laurén classification, and WHO classification, whereas PAI-1 levels showed a significant correlation with advanced lymph node involvement, depth of invasion, tumor stage, site of tumor, and the Laurén, Borrmann, and WHO classifications. Elevated uPA and PAI-1 levels were found to be associated with poor prognosis. The optimal cutoff values indicating a group of patients with shorter survival were 1.5 ng uPA/mg protein and 1.25 ng PAI-1/mg protein, respectively (Classification and Regression Tree analysis). Patients with either high uPA or PAI-1 values were significantly associated with decreased survival (median time of survival was 23 months (high) versus 44 months (low). By univariate Cox regression analysis, it was shown that TNM categories, WHO classification, size of tumor, uPA and PAI-1 levels were all significantly associated with survival. However, in multivariate Cox regression analysis of these grouped variables, nodal status, PAI-1 levels, and WHO classification were the only independent prognostic factors. The relative risks of failure were 5-, 2.9-, and 2.4-fold, respectively. We conclude that PAI-1 and uPA positivity may serve as new prognostic factors in gastric cancer, predicting shorter survival even in clinically important subgroups of patients.

Cytotoxicity of alkyl-lysophospholipid derivatives and low-alkyl-cleavage enzyme activities in rat brain tumor cells.

Alkyl-lysophospholipids (ALP) and related derivatives inhibited the in vitro incorporation of [3H]thymidine into seven different permanent cell lines derived from rat brain tumors. The cytostatic effect of ALP was dependent on dosage and incubation time. Naturally occurring 2-lysophosphatidylcholine did not exhibit cytostatic effects; under these conditions, the incorporation rates of [3H]thymidine were generally more than 100% of the controls. The trypan blue dye exclusion test, which was used to assess severe cell damage, correlated with the extent that [3H]thymidine incorporation was inhibited by ALP. Preincubation of ALP (rac-1-octadecyl-lyso-glycero-3-phosphocholine) for more than 8 min with a tetrahydropteridine-dependent O-alkyl cleavage enzyme preparation from rat liver microsomes destroyed almost all of the cytotoxic properties of ALP when tested at a concentration that previously inhibited tumor growth by more than 50%. [3H]Thymidine incorporation rates were greater than 100% for astrocytoma cells incubated with ALP after exposure to the alkyl cleavage enzyme. Comparison of the microsomal activities of the tetrahydropteridine-dependent alkyl-cleavage enzyme present in astrocytoma 78-FR-G-299 cells and the pleomorphic glioma 78-FR-G-219/S4 cells to that found in normal skin fibroblasts and rat livers revealed a markedly reduced activity in the neoplastic cell lines. Moreover, those tumor cells that were more resistant to ALP cytotoxicity (pleomorphic glioma, 78-FR-G-219/S4) had a 3-fold higher tetrahydropteridine-dependent cleavage activity than a more cytotoxic sensitive line (astrocytoma cells, 78-FR-G-299). Our results indicate that the low-alkyl-cleavage enzyme activities in these neoplastic cells in comparison to normal cells might be a factor in explaining the relatively high cytotoxicity of ALP in tumor cells.

Seasonal exposure of carbon dioxide ice on the nucleus of comet 67P/Churyumov-Gerasimenko.

Carbon dioxide (CO2) is one of the most abundant species in cometary nuclei, but because of its high volatility, CO2 ice is generally only found beneath the surface. We report the infrared spectroscopic identification of a CO2 ice-rich surface area located in the Anhur region of comet 67P/Churyumov-Gerasimenko. Spectral modeling shows that about 0.1% of the 80- by 60-meter area is CO2 ice. This exposed ice was observed a short time after the comet exited local winter; following the increased illumination, the CO2 ice completely disappeared over about 3 weeks. We estimate the mass of the sublimated CO2 ice and the depth of the eroded surface layer. We interpret the presence of CO2 ice as the result of the extreme seasonal changes induced by the rotation and orbit of the comet.

High frequency of simultaneous loss of p16 and p16beta gene expression in squamous cell carcinoma of the esophagus but not in adenocarcinoma of the esophagus or stomach.

Quantitative reverse transcription PCR (RT-PCR) was used to measure gene expressions (relative mRNA levels) of p16 and the alternate transcript pl6beta in esophageal and gastric tumors. p16 gene expression was undetectable in 13 of 25 esophageal squamous cell carcinomas. In 11 of these tumors, pl6beta was simultaneously missing whereas two of the pl6-deficient tumors still expressed p16beta. Among 34 esophageal adenocarcinomas and 11 gastric adenocarcinomas, only one tumor lacked p16 expression and all tumors expressed p16beta. p16 sequences were not detectable by PCR in genomic DNA from tumors lacking both p16 and p16beta mRNA, suggesting that the simultaneous loss of both gene expressions resulted from homozygous genomic deletion of the p16 gene. However, DNA from tumors that lacked p16 mRNA but expressed pl6beta did contain the p16 gene, consistent with loss of p16 expression in these tumors by transcriptional suppression. No point mutations in p16 cDNA were detected among 12 that were sequenced, but one p16 cDNA from a squamous cell carcinoma had a 19-base deletion, possibly indicating a splice-site mutation. Among those tumors that expressed p16 mRNA, the gene expression values of both p16 and pl6beta varied over a wide range. In some cases, p16 expression was detectable but low, suggesting that down-regulation of p16 expression may be used in some cases to achieve the funtional equivalent of gene deletion or transcriptional silencing. These results demonstrate that p16 expression patterns differ based on tumor histology and origin. Homozygous deletion of p16 appears to be common in esophageal squamous cell carcinomas but in adenocarcinomas, both gene deletion and transcriptional silencing of p16 were infrequent.

Phase II study with the combination etoposide, doxorubicin, and cisplatin in advanced measurable gastric cancer.

In this phase II multicenter trial, 67 evaluable patients with advanced measurable gastric carcinoma were treated with a combination of etoposide, Adriamycin (doxorubicin; Adria Laboratories, Columbus, OH), and cisplatin (EAP). The overall response rate was 64%, including 21% complete responses (CRs). In 55 patients with metastatic disease, 31 responses (51%) including eight CRs (15%) were achieved. Responses were seen in all metastatic sites, but the response rate was lower in patients with peritoneal carcinomatosis. In 12 patients with locoregional disease, six CRs and six partial responses (PRs) were observed. Eight CRs (three and five in patients with metastatic and locoregional disease, respectively) were pathologically confirmed. The overall median response duration was 7 months; it was 16 months for patients achieving CR (22 months for pathologically confirmed CR [pCR]), and 6 months for PR. The median survival time for all patients was 9 months, for the patients who achieved CR 17 months, for pCR 23 months, and for PR 9.5 months. Median survival time for all patients with metastatic disease was 8 months, and for locoregional disease 12.5 months. Six patients (9%) (four local, two metastatic disease) were alive at 2 years, and four patients are alive and disease free at 35+ to 56+ months. Main toxicities were leukopenia and thrombocytopenia, with 64% of patients developing grade 3 to 4 myelosuppression and 12% severe infections. Nonhematologic toxicities of World Health Organization (WHO) grade 4 were not observed.

Preoperative chemotherapy in locally advanced and nonresectable gastric cancer: a phase II study with etoposide, doxorubicin, and cisplatin.

Thirty-four patients with locally advanced, nonresectable gastric cancer (staged by laparotomy) received etoposide, Adriamycin (doxorubicin; Adria Laboratories, Columbus, OH), and cisplatin (EAP). Thirty-three patients were evaluable for response and toxicity. Second-look surgery with removal of residual tumor by gastrectomy and lymphadenectomy was performed in case of complete/partial remission (CR/PR) after EAP. After successful resection (R0- and R1-resection), two cycles of EAP were administered for consolidation therapy. Patients refusing reoperation received up to six cycles of EAP. The response rate (CR/PR) after EAP was 70% (23/33), including a 21% (7/33) rate of clinical CRs (CCRs). Two patients had minor remission (MR)/no change and seven had progressive disease. There was one early death. Nineteen of 23 responders (5 CCRs, 14 clinical PRs [CPRs]) and one patient with MR underwent second-look surgery. Five CCRs were pathologically confirmed; 10 patients with CPR were without evidence of disease (NED) after resection. In three patients (CPR), R1-resections (microscopically tumor-cell positive proximal margin) were performed; two patients are disease-free, 22+ and 33+ months after consolidation chemotherapy. In two patients, the tumor was again considered nonresectable. Twenty patients were disease-free after EAP +/- surgery +/- consolidation chemotherapy. Toxicity was primarily hematologic. Leukopenia and thrombocytopenia of World Health Organization (WHO) grade 3 occurred in 30% and 9%, respectively and grade 4 in 18% and 9% of the patients, respectively. There was no increased peri- or postoperative morbidity. After a median follow-up of 20 months for disease-free patients, the relapse rate is 60% (12/20). The median survival time for all patients is 18 months and for disease-free patients 24 months. EAP is highly effective in locally advanced gastric cancer, and offers a chance for surgery with curative intention in patients with an otherwise fatal prognosis.

Prediction of response to preoperative chemotherapy in adenocarcinomas of the esophagogastric junction by metabolic imaging.

PURPOSE: Preoperative chemotherapy in patients with gastroesophageal cancer is hampered by the lack of reliable predictors of tumor response. This study evaluates whether positron emission tomography (PET) using fluorine-18 fluorodeoxyglucose (FDG) may predict response early in the course of therapy. PATIENTS AND METHODS: Forty consecutive patients with locally advanced adenocarcinomas of the esophagogastric junction were studied by FDG-PET at baseline and 14 days after initiation of cisplatin-based polychemotherapy. Clinical response (reduction of tumor length and wall thickness by > 50%) was evaluated after 3 months of therapy using endoscopy and standard imaging techniques. Patients with potentially resectable tumors underwent surgery, and tumor regression was assessed histopathologically. RESULTS: The reduction of tumor FDG uptake (mean +/- 1 SD) after 14 days of therapy was significantly different between responding (-54% +/- 17%) and nonresponding tumors (-15% +/- 21%). Optimal differentiation was achieved by a cutoff value of 35% reduction of initial FDG uptake. Applying this cutoff value as a criterion for a metabolic response predicted clinical response with a sensitivity and specificity of 93% (14 of 15 patients) and 95% (21 of 22), respectively. Histopathologically complete or subtotal tumor regression was achieved in 53% (eight of 15) of the patients with a metabolic response but only in 5% (one of 22) of the patients without a metabolic response. Patients without a metabolic response were also characterized by significantly shorter time to progression/recurrence (P =.01) and shorter overall survival (P =.04). CONCLUSION: PET imaging may differentiate responding and nonresponding tumors early in the course of therapy. By avoiding ineffective and potentially harmful treatment, this may markedly facilitate the use of preoperative therapy, especially in patients with potentially resectable tumors.

Combined preoperative chemotherapy and radiotherapy in patients with locally advanced esophageal cancer. Interim analysis of a phase II trial.

PURPOSE: The prognosis of patients with locally advanced esophageal cancer (LAEC) remains poor when treated with local modalities. An intensive preoperative program with chemoradiotherapy was used to evaluate the curative resection rate, pathologic response, and survival of patients with LAEC. PATIENTS AND METHODS: Ninety patients with LAEC were treated preoperatively with chemotherapy (three courses of fluorouracil, leucovorin, etoposide, and cisplatin [FLEP]) followed by concurrent chemoradiotherapy (one course of cisplatin plus etoposide in combination with 40 Gy of radiation). Transthoracic esophagectomy was performed 4 weeks after the end of radiation. RESULTS: Seventy-two patients were included in this evaluation. Forty-four (61%) underwent a complete tumor resection, and 16 (22%) had no tumor in the resected specimen (pathologic complete response [PCR]). The operative mortality rate was 15%. At a median follow-up time of 22 months (range, 12 to 41), the median survival duration of all 72 patients was 17 months (range, 1 to 41+). The calculated survival rates at 3 years were 33%, 42%, and 68% for all patients, patients after complete resection, and patients with PCR, respectively. CONCLUSION: This combined treatment modality is active in LAEC, with a PCR in 33% of the patients undergoing surgery. The results appear improved compared with those reported with surgery alone, by approximately doubling the 3-year survival rate. The high efficacy of preoperative chemoradiation warrants evaluation of the role of surgery in LAEC.

Strong prognostic impact of tumor-associated urokinase-type plasminogen activator in completely resected adenocarcinoma of the esophagus.

The serine protease system has been shown to play an important role in the invasive potential of a variety of tumors. To date, however, there are little data about the expression of these proteases in esophageal carcinoma. To determine the level of expression and the significance of urokinase-type plasminogen activator (uPA) and its plasminogen activator inhibitor type 1 (PAI-1) in adenocarcinoma of the esophagus, we studied 54 tumor cases and a control group of normal gastric mucosa cases with ELISA using detergent-extracted samples. uPA and PAI-1 were significantly elevated as compared to control tissue by factors of 16 and 14, respectively. Median levels of both uPA and PAI-1 showed significant correlation with tumor pT, pN, and pM categories, whereas the presence of lymphatic invasion correlated only with the uPA content and tumor grade correlated only with PAI-1 content. Using maximally selected statistics, a cutoff value was found for uPA (2.85 ng/mg protein) but not for PAI-1, which divided the study group into significantly poorer and better survival subgroups. By univariate analysis, depth of tumor invasion (pT), lymph node involvement (pN), number of involved lymph nodes, lymph node ratio, distant nodal metastases [pM1(Iym)], lymphatic invasion, and uPA showed significant correlations with patient survival. By multivariate analysis, uPA (first rank), pN, and pM (lym) were identified as independent prognostic factors, with relative risks of 8.4, 4.1, and 4.3, respectively. In a second survival analysis method, a prognostic model was developed using classification and regression trees analysis, in which a significant difference among three patient survival groups was distinguished using the variables "number of involved lymph nodes" and "uPA content." In summary, tumor uPA content as determined by ELISA appears to be a powerful, independent prognostic factor for survival in adenocarcinoma of the esophagus.

Expression of apoptosis-regulating proteins and outcome of esophageal cancer patients treated by combined therapy modalities.

The present study retrospectively examines the correlation between the outcome of patients with locally advanced esophageal squamous cell carcinoma (LAEC) after multimodal treatment (radiochemotherapy +/- surgery) and the expression of apoptosis-regulating proteins in pretherapeutic biopsies. Thirty-eight patients with LAEC who took part in a prospective multicentric trial received radiochemotherapy, optionally followed by surgery. Pretreatment tumor biopsies were immunohistochemically investigated for expression of p53, Bcl-2, Bax (bcl-2-associated X protein), and Bcl-X(L) (bcl-2-related X protein). The overall expression of p53, Bcl-2, Bax, and Bcl-X(L) was 52.6, 57.9, 100, and 97.4% respectively. Tumors without p53 expression and tumors with weak Bcl-X(L) expression showed response to chemotherapy more frequently (55.6 and 52.6%, respectively) than tumors positive for p53 expression and tumors with strong Bcl-X(L) expression (30.0 and 31.6%, respectively); however, these differences did not attain statistical significance. No correlations were found between the expression of Bcl-2 and Bax and the response to chemotherapy. In patients treated by radiochemotherapy and surgery, p53-negative tumors showed a significantly better outcome than p53-positive tumors (mean survival, 31.1 months versus 11.3 months; P = 0.0378). Additionally, a more favorable outcome was observed in tumors positive for Bcl-2 (not significant), whereas no differences in survival were observed in relation to the expression of Bax or Bcl-X(L). No differences in survival were observed in patients treated by radiochemotherapy without subsequent resection therapy in relation to the expression of apoptosis-regulating proteins. Immunohistochemical examination of pretherapeutic tumor biopsies for expression of apoptosis-regulating proteins may help to identify patients with LAEC who may benefit from multimodal treatment and those who may not.

Loss of heterozygosity and microsatellite instability as predictive markers for neoadjuvant treatment in gastric carcinoma.

We analyzed a group of gastric carcinomas treated with a cisplatin-based neoadjuvant chemotherapy regimen for microsatellite instability (MSI) and loss of heterozygosity (LOH) to determine whether there is any relation between microsatellite alterations and therapy response. Pretherapeutic endoscopic biopsies of 37 patients were studied at 11 microsatellite loci. Thirteen (35%) had a complete or partial clinical response (responders), and 24 (65%) had only a minor or no response (nonresponders). High-grade MSI was found in two tumors, both nonresponders, whereas low-grade MSI was found in five biopsies, including three non-responders and two responders. Regarding LOH, the most obvious differences between the groups were observed on chromosome 17p13, the location of the p53 gene, with 7 of 12 (58%) and 3 of 20 (15%) of the informative tumors exhibiting LOH in responders and nonresponders, respectively (P = 0.018). A statistically significant difference was also observed in the fractional allelic loss (FAL) ratio of the groups. Among the 13 responding patients, 7 (54%) tumors exhibited high FAL (>0.5-0.75), 2 (15%) showed medium FAL (>0.25-0.5), and 4 (31%) demonstrated low FAL values (0-0.25), whereas among the 22 nonresponding patients, 2 (9%) tumors showed high FAL, 5 (23%) showed medium FAL, and 15 (68%) showed low FAL (P = 0.020). These data suggest that LOH at chromosome 17p13 is associated with a good clinical response to cisplatin-based chemotherapy, suggesting that altered p53 function might render cells more sensitive to therapy. Furthermore, the association of FAL with therapy response indicates that gastric carcinomas with a high level of chromosomal alteration may be more sensitive to this type of chemotherapy.

P53 mutational status improves estimation of prognosis in patients with curatively resected adenocarcinoma in Barrett's esophagus.

The incidence of adenocarcinomas in Barrett's esophagus has been rising in the last two decades in the United States and Western Europe for yet unknown reasons. We reported previously a large multi-institutional trial implicating p53 mutations as being involved in the pathogenesis of Barrett's cancer and representing an early marker for the malignant potential of Barrett's epithelium. A prospective study was performed to evaluate the prognostic impact of p53 mutations on survival in 59 patients with Barrett's cancer. Tissue for DNA analysis was obtained by endoscopic biopsy or immediately after surgical resections from the tumor, Barrett's epithelium, and normal stomach and esophagus. p53 mutation analysis was performed by PCR-single strand conformational polymorphism screening of exons 5-9 and DNA sequencing to unequivocally prove the presence of a mutation. p53 mutations were identified in 30 of 59 (50.8%) patients. The presence of a p53 mutation in the tumor had a significant impact on survival after curative resections (RO-resections) with cumulative 5-year survival probabilities of 68.8+/-9.7% for mutation-negative tumors and 24.3+/-9.9% for mutation-positive tumors (log rank: P < 0.001). By Cox proportional hazard analysis, including the parameters of gender, age, Union International Contre Cancer tumor stage, grading, and p53 mutation status, only Union International Contre Cancer tumor stage (P < 0.0001) and p53 mutation status (P < 0.02) were of significant independent prognostic importance. p53 mutation analysis by DNA sequencing is of significant independent prognostic importance next to histopathological tumor stage in patients with curatively resected (RO-resection) Barrett's cancer. It appears that p53 mutational status is a valuable parameter to define low-risk (p53 mutation-negative) and high-risk (p53 mutation-positive) groups for treatment failure after curative resections.

Expression of p21WAF1 predicts outcome of esophageal cancer patients treated by surgery alone or by combined therapy modalities.

The p21WAF1 protein is an important regulator of the cell cycle. Its expression and prognostic significance were investigated immunohistochemically in samples of normal esophageal squamous epithelium (n = 10), severe squamous cell dysplasia (n = 20), carcinoma in situ (n = 14), permanent esophageal squamous cell carcinoma cell lines (n = 3), and invasive squamous cell carcinomas treated either by potentially curative resection (n = 172) or by combined modality therapy (radiochemotherapy +/- surgery; n = 38). Whereas p21WAF1 expression in the normal epithelium was restricted to a few cells adjacent to the basal cell layer, p21WAF1 overexpression was frequently found in preneoplasias and invasive carcinomas. Expression of p21WAF1 in invasive carcinomas was not correlated with tumor differentiation, pT category, or pN category. Among carcinomas treated by potential curative resection, univariate (P = 0.0025) and multivariate (P = 0.0081) survival analysis showed significant correlation of strong p21WAF1 expression (> or =50% p21WAF1-positive tumor cells) with poor overall survival. Univariate survival analysis (P = 0.0006) revealed the same prognostic influence in the group of patients treated by combined modality therapy. We conclude that overexpression of p21WAF1 protein is a frequent event in preneoplasias and neoplasias of the esophagus. Immunohistochemical examination of p21WAF1 expression may provide important prognostic information for decision-making in the treatment of patients with esophageal cancer.