Gender-specific effects of oral hypoglycaemic agents on cancer risk in type 2 diabetes mellitus

AIMS

To analyse the association between cancer incidence and oral diabetes therapy (biguanide, sulphonylurea, thiazolidinedione and meglitinide) in men and women with type 2 diabetes mellitus.

METHODS

A retrospective analysis of the electronic health record-based Cleveland Clinic Diabetes Registry (25 613 patients) was cross-indexed with the histology-based tumour registry (48 051 cancer occurrences) over an 8-year period (1998-2006). Multiple imputations were used to account for missing data. Cox regression with propensity scores was used to model time for the development of incident cancer in each of the imputed datasets and the results were pooled.

RESULTS

During 51 994 person follow-up years, 892 incident cancer cases were identified; prostate (14.5%) and breast (11.7%) malignancies were most frequent. In women, thiazolidinedione use was associated with a 32% decreased cancer risk compared with sulphonylurea use [hazard ratio (HR) 0.68; 95% confidence interval (CI) 0.48-0.97, in the adjusted analysis]. Comparison of insulin secretagogues (sulphonylurea and meglitinide) versus insulin sensitizers (biguanide and thiazolidinedione) demonstrated a 21% decreased cancer risk in insulin sensitizers [HR 0.79 (95% CI 0.64-0.98) in the adjusted analysis]. Oral diabetes therapy showed no significant difference in men. Adjustments were made for age, body mass index (BMI), low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglycerides, coronary heart disease (CHD), diabetes oral monotherapy, race, gender, haemoglobin A1c, statin use, income, insulin use, glomerular filtration rate (GFR), new diabetes status, prior cancer, prior cerebrovascular accident (stroke or transient ischaemic event), systolic/diastolic blood pressure, tobacco use (ever/never) and the propensity score for receiving a biguanide.

CONCLUSIONS

Oral insulin sensitizers, particularly thiazolidinedione, are associated with decreased malignancy risk in women with type 2 diabetes mellitus.

3-[1-(4-Bromo-phen-yl)eth-oxy]-2,2,5-trimethyl-4-phenyl-3-aza-hexa-ne

The title compound, C22H30BrNO, is an alk-oxy-amine compound, an effective initiator in nitroxide-mediated free radical polymerization. It was prepared as a mixture of two diasteromers; the crystal for the X-ray analysis showed one of these as a pair of R,S and S,R enanti-omers. The tert-butyl and isopropyl groups are in an almost anti conformation in the crystal [C-N-C-C torsion angle = -168.8 (1)°], and the methyl group of the ethoxy group is in an approximate anti relationship to the tert-butyl group. The dihedral angle between the phenyl and benzene rings is 33.12 (7)°. The Br atom is disordered over two positions, with occupancies of 0.9139 (16) and 0.0861 (16). In the crystal, weak C-H⋯Br contacts link the mol-ecules into chains along [-110].

Higher capecitabine AUC in elderly patients with advanced colorectal cancer (SWOGS0030)

Background:

The aging process is accompanied by physiological changes including reduced glomerular filtration and hepatic function, as well as changes in gastric secretions. To investigate what effect would aging have on the disposition of capecitabine and its metabolites, the pharmacokinetics between patients ⩾70 years and <60 years were compared in SWOG0030.

Methods:

Twenty-nine unresectable colorectal cancer patients were stratified to either ⩾70 or <60 years of age, where the disposition of capecitabine and its metabolites were compared.

Results:

Notable increase in capecitabine area under the curve (AUC) was accompanied by reduction in capecitabine clearance in ⩾70 years patients (P<0.05). No difference in 5'-deoxy-5-fluorocytidine, 5'-deoxy-5-fluorouridine (DFUR), and 5-fluorouracil (5FU) AUCs between the two age groups, suggesting that carboxylesterase and cytidine deaminase (CDA) activity was similar between the two age groups. These results suggest that metabolic enzymes involved in converting capecitabine metabolites are not altered by age. An elevation in capecitabine Cmax and reduction in clearance was seen in females, where capecitabine AUC was 40.3% higher in women. Elevation of DFUR Cmax (45%) and AUC (46%) (P<0.05) was also noted, suggesting that CDA activity may be higher in females.

Conclusion:

Increases in capecitabine Cmax and AUC was observed in patients ⩾70 years when compared with younger patients who were >60 years.

Reported family history of cancer in 1,271 prostate cancer cases and 1,909 controls

Prostate cancer risk has been associated with a family history of the disease. A two- to three-fold increase in risk has been observed in several studies. Details concerning modification of this risk by age, type of familial history of prostate cancer, and possible involvement of history of cancer at other sites have been less well documented. This case-control study of 1,271 prostate cancer patients and 1,909 control subjects admitted to Roswell Park Cancer Institute in Buffalo, NY, found age-adjusted increased risk associated with reporting a history of prostate cancer in a father (RR = 2.3, 95% Cl 1.4-3.3) or brother (RR = 2.5, 95% Cl 1.6-3.9). Subjects with both a father and brother affected had a 6.5-fold (95% Cl 1.4-30.5) increased risk of prostate cancer. Greater risk were observed at younger ages of diagnosis. Risks associated with reporting a father or a brother affected were not significantly elevated for patients over age 70 at diagnosis. No significant differences in patients reporting histories of cancer other than prostate cancer were observed regardless of relationship, age at diagnosis, or type of cancer examined. These observations from a large cancer patient population may be useful when making recommendations for cost-effective prostate cancer screening and for directing investigators to the potentially most informative subjects.

Recruitment of ethnic minorities into cancer clinical trials: experience from the front lines

Throughout the world there are problems recruiting ethnic minority patients into cancer clinical trials. A major barrier to trial entry may be distrust of research and the medical system. This may be compounded by the regulatory framework governing research with an emphasis on written consent, closed questions and consent documentation, as well as fiscal issues. The Leicester UK experience is that trial accrual is better if British South Asian patients are approached by a senior doctor rather than someone of perceived lesser hierarchical status and a greater partnership between the hospital and General Practitioner may increase trial participation of this particular ethnic minority. In Los Angeles, USA, trial recruitment was improved by a greater utilisation of Hispanic staff and a Spanish language-based education programme. Involvement of community leaders is essential. While adhering to national, legal and ethnical standards, information sheets and consent, it helps if forms can be tailored towards the local ethnic minority population. Written translations are often of limited value in the recruitment of patients with no or limited knowledge of English. In some cultural settings, tape-recorded verbal consent (following approval presentations) may be an acceptable substitute for written consent, and appropriate legislative changes should be considered to facilitate this option. Approaches should be tailored to specific minority populations, taking consideration of their unique characteristics and with input from their community leadership.

Nanocharacterization of Surface and Interface of Different Epoxy Networks

The effect of network changes on the surface and interface properties of amine-cured epoxy has been investigated. Samples of different crosslinked epoxies are prepared by mixing stoichiometrically pure diglycidyl ether of bisphenol A (n=0.03) with different ratios of 1,3-bis(aminomethyl)cyclohexane (terafunctional amine) and cyclohexylmethylamine (difunctional amine). All samples are cured in CO2-free air. Both the film surface in contact with air and that in contact with the silicon substrate (the interface) are analyzed using atomic force microscopy (AFM) and nanoindentation. Small angle neutron scattering (SANS), attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, and contact angle measurements, are used to assist in the interpretation of AFM results. Substantial morphological and mechanical differences are observed between the surface and the interface for different crosslinked epoxies. The findings have strong implications on the wettablity, adhesion, and durability of amine-cured epoxies.

The need for better data about counterfeit drugs in developing countries: a proposed standard research methodology tested in Chennai, India

WHAT IS KNOWN AND OBJECTIVE

There is still surprisingly little basic research data to support widely repeated claims about the prevalence of drug counterfeiting. To meet the need for more reliable drug quality data, we designed a study framework that includes clear definitions of measured end points, sampling methods and assay technique. Our objective was to test this research design in Chennai (formerly Madras), India, using a joint Indian and Canadian team.

METHODS

The city was divided into ten areas along municipal lines. From each area, ten stores and pharmacies selling drugs were selected. At each of these 100 outlets, three study drugs (artesunate, ciprofloxacin and rifampicin) were purchased. The 300 samples were tested by Liquid Chromatography-Mass Spectrometry. Assay content was expressed as a percentage of stated tablet content. Based on assay results and their distribution, we developed drug quality definitions for normal manufacturing standards, counterfeiting, decomposition, poor quality control and adulteration.

RESULTS

The group mean for ciprofloxacin was close to normal manufacturing limits (99·2 ± 7·1%) but rifampicin (91·6 ± 5·7%), and artesunate (80·1 ± 9·1%), were both below normal pharmaceutical standards. Overall, 43% of all samples fell below the widely accepted manufacturing range of 90-110% of stated content. No tablet from any sample contained less than 50% of the stated dose.

WHAT IS NEW AND CONCLUSION

The quality of at least some anti-infective drugs in Chennai is below commonly accepted standards but we found no evidence of criminal counterfeiting. Poor drug quality was most likely due to decomposition during storage or poor manufacturing standards. Our research methodology worked well under practical conditions and should hopefully be of value to others working in this area.

StarClose vascular closure device: safety and efficacy of deployment and reaccess in a neurointerventional radiology service

BACKGROUND AND PURPOSE

Obtaining safe and effective closure of the femoral access site following neurointerventional procedures can sometimes be challenging, especially in patients on anti-coagulation or anti-platelet therapy. The purpose of this study was to evaluate the safety and efficacy of a novel percutaneous closure device that employs a nitinol clip-mediated extravascular closure strategy following neurointerventional procedures.

MATERIALS AND METHODS

We performed a retrospective review of all patients who underwent neurointerventional procedures at our institution between January 1, 2006 and December 31, 2008. We evaluated the safety and efficacy of the StarClose device in patients undergoing first and repeat procedures. Groin complications were classified as self-limited hematoma, hematoma requiring transfusion, other/minor (pseudoaneurysm, infection), and other/major (vascular complication).

RESULTS

StarClose device use was attempted in 281 of 352 cases (79.8%) with success reported in 269 cases (95.7%). Minor and major complications occurred in 0.7% and 0.4% of patients, respectively. There was one major vascular complication. Repeat use was performed in 84 patients with 100% success and a 2.3% minor complication rate. Time to reaccess ranged from 1 to 1036 days (mean, 105 days).

CONCLUSIONS

The StarClose device achieves rapid and safe femoral arterial closure in patients, both for primary closure and after reaccess.

Randomized trial of p53 targeted adjuvant therapy for patients (pts) with organ- confined node-negative urothelial bladder cancer (UBC)

5017

Background: Retrospective studies suggest that p53 mutation and associated immunohistochemical (IHC) detectable expression are prognostic for recurrence in pts with organ confined UBC and may be predictive for benefit from MVAC adjuvant chemotherapy. Methods: Pts with pT1–2N0M0 UBC following radical cystectomy and bilateral pelvic lymph node dissection were eligible. IHC for p53 was centrally performed and pts with ≥10% nuclear reactivity were offered randomization to 3 cycles of adjuvant MVAC vs. observation. P53 negative and p53 positive pts who declined randomization were observed. Primary endpoint was recurrence-free survival (RFS) in the randomized population. Secondary endpoints were RFS in p53 negative versus p53 positive pts and overall survival in each of these groups. Using a one-sided log-rank test with α = 0.05 and β = 0.15, 190 p53 positive patients were planned to be randomized to detect an absolute improvement in RFS at 3 years (yrs) from 50% to 70% (corresponding hazards ratio of 0.51). Results: 521 pts were registered, 499 underwent successful p53 assessment (male: 80%, <65 yrs: 57%, Caucasian: 91%, pathologic stage P1/P2: 37%/63%, lymphovascular invasion: 20% yes/28% unknown), 272 (55%) were p53 positive and 114 were randomized (42%). Further accrual was halted based on data safety monitoring board review of futility analysis on the first 100 randomized pts. P53 positive tumors were higher grade (97% vs 93% grade 3/4, p = 0.04) and less likely to express p21 (59% vs 84%, p < 0.001). Overall 5-yr RFS was 80 ± 2% with no difference based on p53 status. P53 positive patients declining were older but otherwise similar to those accepting randomization. Only 67% of pts randomized to MVAC received all 3 cycles with 12 (21%) receiving none. There was no difference in RFS in the randomized population (overall 5 yr RFS 83 ± 4%, hazard ratio = 0.88, p = 0.78). Conclusions: The prognostic and predictive value of p53 IHC were not confirmed in this prospective study, but the lower than expected event rate and failures to receive assigned therapy severely compromised the study's power. The value of p53 mutations is being assessed.

No significant financial relationships to disclose.

Multi-center study evaluating circulating tumor cells (CTCs) as a surrogate for survival in men treated for castration refractory prostate cancer (CRPC)

5016

Background: Monitoring CTCs in patients undergoing therapy for metastatic breast cancer is an effective means to predict outcome and monitor treatment. The primary endpoint of this prospective multi-center study was to demonstrate a significant relation between the presence of CTCs and survival in men treated for CRPC. Methods: 276 patients with diagnosed CRPC, PSA progression, and an ECOG score of 0–2 about to begin initial or salvage chemo and/or combination therapy were enrolled. CTCs were enumerated with the CellSearch System in blood drawn pre-treatment and monthly thereafter for up to 18 months. Patient data were collected and maintained by an independent CRO. Median overall survival (OS) was determined for patients with =5 CTC /7.5mL at baseline and specified intervals. Results: Of 240 evaluable patients, 142 (59%) are alive - mean follow-up 11.4 ± 4.4 months. Median OS (in months) and significance between the two groups (logrank p-value) at different time points after the initiation of therapy are indicated in the table . Median OS for 40 (19%) patients with a reduction of CTCs below 5 CTCs 2–5 weeks after initiation of therapy was significantly longer as compared to those 78 (38%) patients that remained above 5 CTCs (>20 vs. 9.3mth, p=0.0000) and was not significantly different from the 83 (40%) patients with 20 vs. >20mth, p=0.2725). In multivariate analyses, which included stage at diagnosis, age, ECOG, Gleason score, LDH, Alkaline Phosphotase, and PSA, CTCs remained the most significant independent predictor of outcome. Conclusions: CTC levels in CRPC patients are a strong predictor of OS. The persistence of CTCs after initiation of therapy suggests that the patients are deriving less than optimal benefit from their current therapy. CTC levels may be a valid surrogate end-point in monitoring response to chemotherapy.

[Table: see text]

No significant financial relationships to disclose.

Functional heterogeneity of prostatic intra-epithelial neoplasia: Length of hormonal therapy influences response

4648

Background: Prostatic intraepithelial neoplasia (PIN) is a premalignant lesion of the prostate etiologically linked to prostate cancer. While androgen deprivation therapy (ADT) has been used to reduce prostate cancer, there are controversial data regarding the effect of ADT on PIN. We hypothesized that PIN is a heterogeneous entity with respect to hormone responsiveness, that this may explain aspects of the heterogeneity in the natural history of this disease, and have used the clinical model of ADT followed by radical prostatectomy as a test of this hypothesis. Methods: We performed a retrospective study on a cohort of patients who underwent prostatectomy with biopsy proven prostate cancer. Study patients were those who must have received at least 3 months of ADT at the discretion of their surgeons. Patients from the same cohort who did not undergo ADT were used as controls. Patients were randomly selected from the database and their pathology slides were reviewed by a blinded pathologist looking for presence of PIN with an independent observer. Fisher’s exact test was used to compare the proportions of subjects who had residual PIN in the study group and the control group. Exact logistic regression was used to evaluate the duration of ADT in PIN regression. Results: Eighteen patients initially diagnosed with PIN who did not receive hormonal therapy were identified; 28 patients with PIN who underwent hormonal therapy were also studied. All patients who did not receive hormonal therapy had residual PIN whereas 7 of 28 patients undergoing ADT had no residual PIN (p = 0.043). Evaluation of hormonal therapy between responders and non-responders showed statistically significant association between PIN regression and hormone therapy duration (p < 0.001). However PIN response to ADT was not uniform as 16% of patients with ADT longer than 6 months had residual PIN, suggesting variable sensitivity of PIN to ADT. Conclusions: Our results demonstrate that ADT does cause PIN regression, and that there is heterogeneity in this effect with respect to hormonal duration. We propose for future prospective, multi-centered, randomized trials in which ADT impact on PIN is characterized further.

No significant financial relationships to disclose.

POMB-ACE therapy for patients with international germ cell cancer collaborative group (IGCCCG) poor risk germ cell tumors (GCT): The USC experience

4591

Background: Patients with poor-risk GCT have low rates of cure with standard therapy, with 3 year overall survival (OS) reported at 50% (IGCCCG, JCO 1997). POMB-ACE is a rapidly alternating, dose dense chemotherapy regimen developed to improve outcomes in this population, with reported 3 year OS of 75% (Bower et al, Ann Oncol 1997). We report our experience with this regimen, including analysis of acute and long-term toxicity. Methods: Subjects with poor-risk GCT, defined by IGCCCG criteria as AFP >10,000, bHCG >50,000, LDH > 10 × ULN, non-testicular primary, or non-pulmonary visceral metastases, who were diagnosed at Los Angeles County General Hospital and USC/Norris Cancer Center between 1998 and 2005 were identified using pathology and admission records. All clinical notes and laboratory data were reviewed. Results: Of 23 poor-risk GCT patients identified, 21 received POMB-ACE; 16 were treated at the county facility. 15 patients were Hispanic. 5 had primary mediastinal tumors. 16 were stage IIIC, 4 stage IIIB, and 1 stage IIIA. The median number of cycles was 8 (range 4–12), with a median interval between treatment cycles of 14 days (range 10–39). There were no treatment-related deaths. Febrile neutropenia occurred in 5.9% of treatment cycles, grade 3/4 hematologic toxicity in 19%, and other Grade 3/4 non-hematologic toxicities in 9.8%. G-CSF support was used with 24% of cycles. Nineteen patients (90%) had a partial response, of whom 8 underwent surgery for residual disease; only 1 had residual active tumor, 4 teratoma. Marker-negative status was achieved in 5 patients (23.8%). With median follow-up of 28 months, 9 subjects have recurred (43%) and 4 have died of disease progression. The estimated 2 year disease-free survival is 54%, and 3 year OS 75%. At the end of treatment, residual neuropathy persisted in 2 patients (9.5%), renal compromise in 2 (9.5%), pulmonary toxicity in 3 (14%), and otoxicity in 1 patient (4.7%). Conclusions: In our modern North American experience, POMB-ACE is feasible to administer, even in an uninsured population. This is an effective option in poor-risk GCT patients, with 3 year OS exceeding that achieved with standard therapy. Acute toxicity is modest, however persistent adverse sequelae are common.

No significant financial relationships to disclose.

Absolute PSA value after androgen deprivation (AD) is a strong independent predictor of survival in new metastatic (D2) prostate cancer (PCa): Data from Southwest Oncology Group Trial 9346 (INT-0162)

4517

Background: PSA is a biomarker for monitoring disease activity in PCa. It is not well established if absolute PSA values achieved after AD is prognostic in patients (pts) with new D2 PCa. Methods: Hormone naive D2 pts with baseline PSA ≥ 5ng/mL are treated with 7 months (ms) AD induction. Pts achieving PSA-n (PSA ≤ 4.0 ng/ml that is stable or declining on ms 6 and 7) are randomized to continuous vs. intermittent AD on month 8. To be eligible for this analysis (approved by Data Safety Monitoring Committee), pts had to have a prestudy PSA with at least 2 subsequent PSAs during induction and be registered at least 1 year prior to analysis date. Survival was defined from 8 months to death due to any cause. Associations were evaluated by proportional hazards regression models. P≤0.05 was statistically significant. Results: Of the first 1,395 registered pts, 1345 were eligible for this analysis. Median age was 70 years, median baseline PSA 76.1 ng/mL, 38% had bone pain (BP) and 47 % had Gleason sum (GS) > 7. Median number of on-study PSAs during induction was 5 (range: 2 -18). Of the 1,345 pts, 1134 achieved PSA-n with 965 maintaining PSA-n at end of induction. Of those achieving PSA-n, 604 (45% of all pts) had an undetectable PSA (PSA-u, ≤ 0.2 ng/mL) at end of induction. In multivariate analysis, 4 significant independent risk factors were associated with post-induction survival: Performance status, GS, BP, and being randomized. After adjustment for these factors, pts who had a PSA-n at the end of induction but not PSA-u had less than half the risk of death (RoD) as those who did not have PSA-n (HR: 0.41; 95% CI 0.32, 0.54, p < 0.001), and pts with PSA-u had about one-quarter the RoD as pts with no PSA-n (HR: 0.26; 95% CI 0.20, 0.35, p < 0.001). After adjustment for covariates, pts with PSA-u had significantly better survival than those with only PSA-n at end of induction (p < 0.001). The median overall survival was 13 ms for the 383 not normalized (95% CI: 11 to 16 ms), 44 ms for the 360 pts normalized but not undetectable (95% CI: 39 to 55 ms), and 75 ms for the 602 pts with PSA-u (95% CI: 62, 91 ms). Conclusion: Achieving a PSA-n or PSA-u after 7 ms of AD is a strong predictor of survival and should be used to tailor future trial design in new D2 pts.

[Table: see text]

Increased late toxicity in 12–20 year survivors of germ cell tumors (GCT)

4509

Background: There is extensive literature on occurrence of late effects of cisplatin-based chemotherapy, but it comes from centers of excellence and may reflect case selection or ascertainment biases. Funded by the NIH SEER Program and the Lance Armstrong Foundation, we studied community-based late outcomes via identification of cases from the Los Angeles SEER Tumor Registry and comparison with a control group. Methods: We identified 951 patients treated in Los Angeles County through the records of the L.A. SEER Cancer Registry/Cancer Surveillance Program (CSP) for 1983–1987, giving a minimum follow-up of 12 years. Consent was obtained from physician of record and forms sent to the patients, requesting information about a broad range of demographic, treatment-related and psycho-social issues. In addition, patients were asked to provide a “control”, a friend of approximately the same age at time of diagnosis, known to the patient before diagnosis and known not to have a history of testis cancer. Questionnaires were also sent to controls, to allow data comparison with patients. Anticipated initial difficulties included mobility of young males and invalid addresses. This occurred in > 50% of cases, and we used a planned strategy for acquisition through State agencies, Department of Motor Vehicles, etc. Results: Surveys were returned by 298 cases and 67 control subjects, and 35 patients refused. In 1983–87, success rates were lower, and 142 patients had died. An unexpected problem was reluctance or inability of subjects to identify friends of comparable age to provide a control population. Differences in groups are summarized in the Table. Conclusions: Long term survivors with GCT have an excess of late toxicity, including cardiovascular, neurological, hematologic, musculoskeletal and neoplastic problems, which increase with time. These data should assist in design of surveillance protocols.

[Table: see text]

No significant financial relationships to disclose.

PHASE II TRIAL OF TESMILIFENE PLUS MITOXANTRONE AND PREDNISONE FOR HORMONE REFRACTORY PROSTATE CANCER: HIGH SUBJECTIVE AND OBJECTIVE RESPONSE IN PATIENTS WITH SYMPTOMATIC METASTASES

PURPOSE

Symptomatic, hormone refractory prostate cancer (HRCAP) is a major cause of morbidity with a median survival of less than 12 months and a 2-year survival of only up to 10% in most series. Mitoxantrone has been approved by the Food and Drug Administration for HRCAP. Preliminary data suggest that DPPE (N,N-diethyl-2-[4-(phenylmethyl) phenoxy]-ethanamine) or tesmilifene modulates cytotoxics to enhance the anticancer effect. In this phase II trial we assessed whether there is sufficient evidence of enhanced efficacy of DPPE and mitoxantrone to lead to a phase III clinical trial.

MATERIALS AND METHODS

A total of 29 patients with a median age of 73 years, of whom 10% were older than 80 years, with progressive HRCAP received 5.3 mg/kg DPPE intravenously every 3 weeks, 12 mg/m mitoxantrone intravenously every weeks and 5 mg prednisone orally twice daily. All patients had pain at presentation, while 97% had bone metastases, 10% had liver metastases and 17% had lung metastases. Median prostate specific antigen (PSA) was 210 ng/ml (IQR 77 to 430).

RESULTS

Of the patients 75% had some pain improvement, 66% had decreased analgesia, 59% had a PSA decrease of 50% or greater and 45% had a PSA decrease of 75% or greater. Actual (not actuarial) 2-year survival was 21%.

CONCLUSIONS

Despite major limitations of historical comparison the PSA decrease and decreased symptoms with DPPE-mitoxantrone-prednisone compare favorably to those of mitoxantrone-prednisone and docetaxel-estramustine in the literature. The 2-year survival rate of 21% mandates further assessment. This will be tested in a phase III Southwest Oncology Group trial.

Wetting-dewetting transition line in thin polymer films

Thin polymeric films are increasingly being utilized in diverse technological applications, and it is crucial to have a reliable method to characterize the stability of these films against dewetting. The parameter space that influences the dewetting of thin polymer films is wide (molecular mass, temperature, film thickness, substrate interaction) and a combinatorial method of investigation is suitable. We thus construct a combinatorial library of observations for polystyrene (PS) films cast on substrates having orthogonal temperature and surface energy gradients and perform a series of measurements for a range of molecular masses (1800 g/mol < M < 35 000 g/mol) and film thicknesses h (30 nm < h < 40 nm) to explore these primary parameter axes. We were able to obtain a near-universal scaling curve describing a wetting-dewetting transition line for polystyrene films of fixed thickness by introducing reduced temperature and surface energy variables dependent on M. Our observations also indicate that the apparent polymer surface tension gamma(p) becomes appreciably modified in thin polymer films from its bulk counterpart for films thinner than about 100-200 nm, so that bulk gamma(p) measurements cannot be used to estimate the stability of ultrathin films. Both of these observations are potentially fundamental for the control of thin film stability in applications where film dewetting can compromise film function.

Clinical staging of prostate cancer: reproducibility and clarification of issues

The American Joint Committee on Cancer (AJCC) staging system for prostate cancer adopted in 1992 is based on tumor-node-metastasis (TNM) designations. It has been widely accepted for use in local and advanced disease. The purpose of this study was to assess reproducibility of staging among observers and to help clarify staging issues. Twelve prostate cancer cases were sent to 20 physicians with special expertise in prostate cancer including eight urologists, eight radiation oncologists, and four medical oncologists. Physicians were asked to assign a stage based on the 1992 AJCC clinical staging. The most frequently reported stage assigned to each case was taken to be the consensus. Agreement was the percentage of physicians who reported that particular stage. Seventy-five percent of the physicians responded. The overall agreement for assignment of T stage was 63.9%. Differences were found by specialty for inclusion of available information in designating a T stage. The overall agreement for N stage was 73.8%. The most common designation was Nx regardless of availability of a computed tomography scan. The overall agreement for M stage was 76.6%. Without a bone scan the most common designation was Mx regardless of Gleason grade or prostate-specific antigen (PSA). A frequent comment was that PSA was more indicative of disease extent than current clinical staging. The reproducibility of the 1992 clinical AJCC staging is poor even among experts in the field. This problem arises primarily from disagreement regarding which studies are included in assigning a stage. Some of these difficulties are addressed in the 1997 revision. However, the clinical staging does not address the true biological significance of disease in many instances.