Does the addition of oxaliplatin to preoperative chemoradiation benefit cT4 or fixed cT3 rectal cancer treatment? A subgroup analysis from a prospective study.

BACKGROUND: Whether there is any benefit derived from adding oxaliplatin to fluoropyrimidine-based preoperative chemoradiation is currently unknown in cases of advanced cT3 or cT4 tumours. Our aim was to evaluate this issue by analysing a randomized trial, which compared two schedules of preoperative treatment (chemoradiation vs. 5 × 5 Gy with 3 cycles of consolidation chemotherapy) for cT4 or fixed cT3 rectal cancer. PATIENTS AND METHODS: Delivery of oxaliplatin was mandatory to the first part of the study. For the second part, its delivery in both treatment-assigned groups was left to the discretion of the local investigator. We analysed a subgroup of 272 patients (136 in the oxaliplatin group and 136 in the fluorouracil-only group) from institutions that had omitted oxaliplatin in the second part of the study. RESULTS: Circumferential resection margin negative (CRM-) status rate was 68% in the oxaliplatin group and 70% in the fluorouracil-only group, p = 0.72. The pathological complete response rate (pCR) was correspondingly 14% vs. 7%, p = 0.10. Following multivariable analysis, when comparing the CRM- status in the oxaliplatin group to the fluorouracil-only group, the odds ratio was 0.79 (95 CI 0.35-1.74), p = 0.54; there being no interaction between concomitant chemoradiation and 5 × 5 Gy with consolidation chemotherapy; pinteraction = 0.073. For pCR, the corresponding results were 0.47 (95 CI 0.19-1.16), p = 0.10, pinteraction = 0.84. CONCLUSION: No benefit was found of adding oxaliplatin in terms of CRM nor pCR rates for either concomitant or sequential settings in preoperative radiochemotherapy for very advanced rectal cancer.

Ambident ethyl N-nitrosocarbamate anion: experimental and computational studies of alkylation and thermal stability.

Alkylation of N-nitrosourethane tetrabutylammonium salt (2-Bu(4)N) with four electrophiles (MeI, EtI, i-PrI, and PhCH(2)Br) was studied by (1)H NMR in CD(2)Cl(2) and CD(3)CN solutions. The ratio of the three regioisomers N-alkyl-N-nitrosourethane 3, azoxy 4, and O-alkyldiazotate 5 was practically independent of solvent but dependent on the nature of the electrophile. The anion 2 and O-alkyl derivative 5 are thermally unstable and decompose to ethyl carbonates 9 and 10, respectively, with a first-order rate constant (2-Bu(4)N: k = 18.5 +/- 0.1 x 10(-5) s(-1); 5b (R = Et): k = 1.77 +/- 0.02 x 10(-5) s(-1); 5d (R = PhCH(2)): k = 4.78 +/- 0.08 x 10(-5) s(-1) at 35 degrees C in CD(2)Cl(2)). Further kinetic measurements gave activation parameters for the decomposition of 2 (E(a) = 24.2 +/- 0.3 kcal/mol and ln A = 30.9 +/- 0.1). Gas-phase calculations at the MP2(fc)/6-31+G(d)//MP2(fc)/6-31G(d) level showed that the alkylation of 2 involves the lone electron pairs of the N-N-O atoms, and the calculated activation energies correspond well to the observed ratio of regioisomers 3-5. The theoretical analysis of the decomposition processes supports a concerted mechanism with a four-center transition state in the first step for all four compounds. The calculated activation energy order (2 < 5 < 3 < 4) is consistent with the observed order of stability. Decomposition of 2 and 5 is a unimolecular process, giving carbonates 9 and 10 in a single step. In contrast, rearrangement of 3 and 4 leads to alkyl diazonium ions. A detailed theoretical analysis indicates that the rate-determining step for thermal decomposition of 2 is the loss of molecular nitrogen, while in 5 it is the trans-cis isomerization process. The nonconcerted process involving homolytic cleavage of the O-N bond in 5 was found to be significantly less favorable.

Arylpentazoles revisited: experimental and theoretical studies of 4-hydroxyphenylpentazole and 4-oxophenylpentazole anion.

Kinetic measurements for the degradation of 4-hydroxyphenylpentazole (2a) and its salt 2b-NBu4 in CD3OD and in CD2Cl2 provided a set of activation parameters. The resulting free energies of activation in methanol (DeltaG298 = 19.7 kcal/mol for 2a and DeltaG298 = 20.6 kcal/mol for 2b-NBu4) were compared with previous results for the 4-chloro derivative, 2c, and collectively correlated with results of gas-phase calculations at the B3LYP/6-31+G(d,p) level of theory. This, and another linear correlation of the seven computed DeltaG298 values with the previously reported kinetic data of Ugi and Huisgen, gave the basis for the estimation of the stability of pentazole anion (1) and its derivatives in solutions. Thus, N5(-) is predicted to have t(1/2) = 2.2 d, while the half-lifetime for HN5 is expected to be only about 10 min in methanol at 0 degrees C. Controlled ozonolysis of 2b-NBu4 followed by 1H and 15N NMR spectroscopy shows a preferential destruction of the N5 ring, which excludes it from possible methods for preparation of the parent pentazole.

Vibrations of the phenoxyl radical.

Phenoxyl radical (C(6)H(5)O) was prepared photochemically in low-temperature argon matrices. The infrared absorption spectra were obtained for C(6)H(5)O and for the isotopically labeled species C(6)D(5)O and 1-(13)C(12)C(5)H(5)O. All but one IR-active fundamental vibrations were detected, most of them not previously observed. Combination of results from IR linear dichroism measurements on photooriented samples, determination of absolute IR intensities with the help of internal standards, analysis of isotopic shifts, and quantum chemical predictions (B3LYP/cc-pVTZ) led to a detailed assignment of phenoxyl radical vibrations. Significant frequency shifts are observed with respect to previously reported data based on resonance Raman studies in polar solutions. For some vibrations, these shifts reflect environment-induced structural changes, such as increase of the quinoid character of the phenoxyl radical in polar media. In particular, the frequency of the CO stretching vibration, readily observable in both IR and Raman experiments, is extremely sensitive to the environment and can thus be used to probe its polarity.

The infrared spectrum of the matrix-isolated phenyl radical.

We have measured the infrared absorption spectrum of C(6)H(5), /X (2)A(1), in an Ar matrix at 10 K. The experimental frequencies (cm(-)(1)) and polarizations follow. a(1) modes: 3086, 3072, 3037, 1581, 1441, 1154, 1027, 997, 976, 605; b(1) modes: 972, 874, 706, 657, 416; b(2) modes: 3071, 3060, 1624, 1432, 1321, 1283, 1159, 1063, and 587. Three different methods have been used for the production of the phenyl radicals. Infrared absorption spectra of five deuterated isotopomers, C(6)D(5), p-C(6)H(4)D, p-C(6)HD(4), o-C(6)H(4)D, and m-C(6)H(4)D, were recorded to compare experimental frequency shifts with calculated (UB3LYP/cc-pVDZ) harmonic frequency shifts. The use of CO(2) or NO as internal standards enabled the experimental determination of absolute infrared intensities. The linear dichroism was measured with photooriented samples to establish experimental polarizations of each vibrational band. True gas-phase vibrational frequencies were estimated by considering the gas-to-matrix shifts and matrix inhomogeneous line broadening. The phenyl radical matrix frequencies listed above are within +/-1% of the gas-phase vibrational frequencies. The C(6)H(5) frequencies from this paper supersede our earlier values reported in J. Am. Chem. Soc. 1996, 118, 7400-7401. See also: http://ellison.colorado.edu/phenyl.

p53 Protein accumulation as a prognostic marker of preoperative radiotherapy and/or chemotherapy in advanced squamous cell esophageal carcinoma--preliminary report.

The correlation between immunohistochemical detection (IH) of p53 protein and tumor response to preoperative chemotherapy and/or radiotherapy in advanced esophageal squamous cell carcinoma was evaluated. Fifty-six patients with advanced esophageal squamous cell carcinoma were included in the study. All patients were staged and diagnosed microscopically before treatment. Patients were divided into three groups: 17 patients treated with chemotherapy and radiotherapy preoperatively (group I) (cisplatin and 5-fluorouracil, cobalt-60 therapy; total dose 3000 Gy); 19 patients treated with chemotherapy only (group II); and 20 patients who did not receive preoperative therapy (group III). The response of the tumor tissue to preoperative treatment was evaluated macroscopically and microscopically in operated specimens according to the classification: CR, complete response; PR1, major partial response with regression of at least 50% of initial tumor mass; PR2, minor partial response with regression of less than 50% of initial tumor mass. In all 56 patients immunohistochemistry was used to detect anti-p53 antibody (Dako, DO-7) in normal mucosa and cancer tissue. The response of the tumor was similar in both group I and group II. p53 protein was not expressed in the normal esophageal mucosa. A high level of p53 in operated specimens was associated with unfavorable tumor response to preoperative treatment. Therefore, immunohistochemical detection of p53 protein can be considered to predict the outcome of preoperative therapy.

Family history and risk of stomach cancer in Warsaw, Poland.

In a population-based case-control study of stomach cancer conducted in Warsaw, Poland, 464 cases and 480 controls were interviewed to evaluate the role of family history and other risk factors. A greater than threefold increase in risk was associated with a history of stomach cancer in a first degree relative (OR = 3.5; 95% Cl = 2.0-6.2), but no excess risk was seen with other forms of cancer. The risk associated with familial occurrence was not significantly modified by gender, age or ABO blood type, and did not vary with Laurén histologic classification. Our findings add to evidence for a familial predisposition to both diffuse and intestinal types of gastric cancer. Further studies are needed to identify the susceptibility genes and environmental exposures that may account for the familial tendency to stomach cancer.

Risk of stomach cancer in relation to consumption of cigarettes, alcohol, tea and coffee in Warsaw, Poland.

To identify reasons for the high incidence rates of stomach cancer in Poland, we conducted a population-based case-control study in Warsaw. Cases were residents aged 21 to 79 years who were newly diagnosed with stomach cancer between March 1, 1994, and April 30, 1997. Controls were randomly selected from Warsaw residents registered at the nationwide Polish Electronic System of Residence Evidency, frequency-matched to cases by age and sex. Information on demographic characteristics; consumption of cigarettes, alcohol, tea and coffee; diet; medical history; family history of cancer; occupational history; and living conditions during adolescence was elicited by trained interviewers using a structured questionnaire. Included were 464 cases (90% of eligible) and 480 controls (87% of eligible). Among men, the risk of stomach cancer was significantly elevated among current smokers (OR = 1.7, 95% CI = 1.1-2.7) but not among former smokers. The excess risk was largely confined to long-term and heavy smokers, with significant 2-fold excess risk among men who smoked 40 or more pack-years. Among women, an 80% increase in risk was observed in both current and former smokers but dose-response trends were less consistent than among men. Alcohol consumption was not clearly related to risk, and no association was found for drinking regular coffee or herbal tea or using milk/cream in coffee or tea. A significant reduction in risk was linked to daily tea drinking among women, but not among men. Our findings confirm an association with cigarette smoking, which is estimated to account for approximately 20% of stomach cancers diagnosed among Warsaw residents during the study period.

p-Benzyne.

A noble gas matrix at low temperature was used to investigate the photochemical behavior of diacetyl terephthaloyl diperoxide and dipropionyl terephthaloyl diperoxide as well as 1,4-diiodobenzene. All three photoreactions formed small quantities of a compound with IR absorption bands at 725 and 980 cm-1 , which disappeared when the matrix was annealed. These bands correspond to the most intense of the calculated bands (B3LYP) for 1,4-didehydrobenzene (p-benzyne) (1). That decomposition of the peroxides in fact leads to 1 is confirmed by vapor-phase pyrolysis experiments in which (Z)-2 was obtained in high yield.