Biomedical subjects

Melania Pintilie

Publications and source records attributed to Melania Pintilie.

At least 37 records · Page 2Linked to original sources

PubMed2004

Quality of abstracts describing randomized trials in the proceedings of American Society of Clinical Oncology meetings: guidelines for improved reporting.

PURPOSE: To evaluate the quality of reporting in abstracts describing randomized controlled trials (RCTs) included in the Proceedings of American Society of Clinical Oncology (ASCO) meetings and to propose reporting guidelines for abstracts that are submitted to future meetings. METHODS: Guidelines for reporting of RCTs in abstracts were developed by extracting key elements from published guidelines for full reports of RCTs, and modified based on an expert survey. Abstracts presenting results of RCTs with sample size > or = 200 were identified from the ASCO Proceedings for the years 1989 to 1998. Information regarding the quality of each abstract was extracted, and a quality score (possible range, 0 to 10) was assigned based on adherence to the guidelines. RESULTS: Brief description of the intervention, explicit identification of the primary end point, and presentation of results accompanied by statistical tests were regarded by experts as the most important items to include in an abstract, whereas presentation of secondary and subgroup analyses was the least important. Deficiencies in reporting were present in almost all of the 510 abstracts; for example, only 22% of the abstracts provided explicit identification of the primary end point. The median quality score was 5.5 (range, 2.0 to 8.5); the quality score improved with time (P <.0001) and was better for oral or plenary presentations (P =.0003). CONCLUSION: The quality of reporting of RCTs in abstracts submitted to Annual Meetings of ASCO is suboptimal. Although space precludes the inclusion of details required in the final report, abstracts could be improved through the use of explicit minimal guidelines, which are suggested in this article.

Abstracting and Indexing↗

PubMed2004

Stereotactic radiotherapy in the treatment of juxtapapillary choroidal melanoma: preliminary results.

PURPOSE: To evaluate the preliminary results of stereotactic radiotherapy in the management of patients with juxtapapillary choroidal melanoma. METHODS & MATERIALS: A retrospective, consecutive case series of 28 patients with choroidal melanoma located within 2 mm of the optic nerve who were treated with stereotactic radiotherapy at Princess Margaret Hospital, Toronto, between October 1998 and May 2001. RESULTS: Median age was 62 years. Median tumor height was 4.6 mm and median maximum tumor diameter was 9.4 mm. The prescribed radiation dose was 70 Gy in five fractions over 10 days and median follow-up was 18.5 months. Posttreatment, 2 patients developed local tumor regrowth and 3 patients developed liver metastases. Actuarial rates of local tumor control, metastases, and survival at 18 months were 96%, 10%, and 94%, respectively. Actuarial rates of radiation-induced neovascular glaucoma, cataract, retinopathy, and optic neuropathy at 18 months were 20%, 29%, 30%, and 37%, respectively. A higher radiation dose to the lens was associated with an increased risk of cataract (p = 0.02). CONCLUSIONS: Stereotactic radiotherapy offers a noninvasive alternative to enucleation and brachytherapy in the management of juxtapapillary choroidal melanoma. However, further efforts are needed to optimize local tumor control and minimize radiation-induced complications.

Cataract↗

PubMed2004

Skp2 gene copy number aberrations are common in non-small cell lung carcinoma, and its overexpression in tumors with ras mutation is a poor prognostic marker.

PURPOSE: Skp2 plays a critical role in cell cycle progression, especially at the G(1)-S transition, putatively through its control of several cell cycle regulator proteins. The Skp2 gene is located on a region of chromosome 5p that is commonly overrepresented in lung cancer. The present study aimed to evaluate Skp2 abnormalities and their prognostic value in non-small cell lung cancer (NSCLC). EXPERIMENTAL DESIGN: In total 16 NSCLC cell lines and 163 primary tumors were included in studies to measure Skp2 relative gene copy number, mRNA abundance, and protein level. The tumors were also evaluated for p27 protein expression level and ras mutation. These values were correlated with the clinical and pathological features of the patients. RESULTS: Skp2 relative gene copy number aberrations were found in 88 and 65% of NSCLC cell lines and primary tumors, respectively. Overrepresentation was especially common among squamous cell carcinoma (74%). Both gene copy overrepresentation (13%) and loss (35%) were found in adenocarcinoma. Skp2 relative gene copy number was significantly correlated with mRNA and protein levels, but none of these were correlated with p27 protein levels. Neither high Skp2 protein expression nor ras mutation was prognostically significant. In NSCLCs with ras mutation, however, high Skp2 protein expression was a significant independent poor prognostic marker. CONCLUSION: There appears to be a synergistic interaction between high Skp2 protein expression and ras mutation with negative impact on the survival of NSCLC patients.

Adult↗

PubMed2004

Validating the prognostic value of marker genes derived from a non-small cell lung cancer microarray study.

We previously reported that our cDNA microarray analysis of primary non-small cell lung carcinoma (NSCLC) could predict for patients at increased risk of cancer recurrence. From the result of this analysis, we selected 11 genes that were considered candidate prognostic marker genes and used the realtime reverse transcription polymerase chain reaction (RT-PCR) to investigate their expression in the same set of NSCLC cases used in the microarray study. Cluster analysis of the realtime RT-PCR data separated these patients into two groups with significantly different disease-free survivals (log-rank test, P < 0.017). In contrast, cluster analysis failed to confirm the prognostic significance of the realtime RT-PCR results for these 11 genes in a validation series of 92 NSCLC cases. In univariate analysis, hypoxia inducible factor 1alpha, Rho-GDP dissociation inhibitor (GDI) alpha (RhoGDI) and Citron/rho-interacting serine-threonine kinase 21 (Citron K21) were significant prognostic factors for disease-free survival in the entire cohort of 130 NSCLC patients, but none were significant in multivariate analysis. The results demonstrate that the prognostic significance of microarray (SAM) results can be partially validated using realtime RT-PCR, but secondary validation using larger and independent series of tumors is necessary to identify true prognostic marker genes.

Carcinoma, Non-Small-Cell Lung↗

PubMed2004

A phase III randomized study of misonidazole plus radiation vs. radiation alone for cervix cancer.

BACKGROUND AND PURPOSE: A randomized-controlled study of radical radiotherapy for cervical cancer with or without the hypoxic sensitizer, misonidazole was conducted from 1981 to 1984 to investigate its therapeutic benefit. PATIENTS AND METHODS: Seventy-three patients were accrued from the Princess Margaret Hospital, and St John Regional Cancer Centre and randomized to either misonidazole (MISO, n = 39) or placebo (P, n = 34) in addition to radiotherapy. MISO was given orally each day 4 h prior to external beam radiation treatment (45Gy to midplane in 20 daily fractions) at a dose of 0.45 g/m(2), as well as during intra-uterine brachytherapy (40Gy). RESULTS: The 10-year overall survival (OS) for the entire group was 46%, and the disease-free survival (DFS) was 39%. The 10-year OS for patients in the MISO arm was 45%, compared to 49% for the P arm (P = 0.89). The corresponding DFS figures were 36 and 43%, respectively, (P = 0.6). Ten patients (14%) developed severe late complications (grade 3 or 4). The 10-year serious late complication rate was 14% for MISO and 12% for P (P = 0.51). CONCLUSIONS: Misonidazole failed to improve the outcome of patients with cervix cancer treated with radiotherapy.

Adenocarcinoma↗

PubMed2004

Up-regulation of the redox mediators thioredoxin and apurinic/apyrimidinic excision (APE)/Ref-1 in hypoxic microregions of invasive cervical carcinomas, mapped using multispectral, wide-field fluorescence image analysis.

Thioredoxin and apurinic/apyrimidinic excision (APE)/ref-1 are important redox mediators in biochemical pathways that promote cell survival under adverse conditions including hypoxia and oxidative stress. For example, elevated levels occur surrounding vascular infarcts and protect from reperfusion injury. Because elevated thioredoxin or APE/ref-1 is also associated with resistance to certain forms of cancer treatment, we examined their tissue distribution in a series of 110 cervical carcinoma biopsies. Analysis was done using a quadruple fluorescence imaging technique, incorporating carbonic anhydrase IX (CAIX) immunofluorescence to outline hypoxic microregions and 4',6-diamidino-2-phenylindole to localize nuclear staining of thioredoxin and APE/ref-1. A scanning autostage was used to image the entire tissue section. Thioredoxin and APE/ref-1 levels were expressed as the average pixel brightness in tumor tissue, subdivided based on CAIX and 4',6-diamidino-2-phenylindole staining. Results showed that the nuclear and cytoplasmic levels of thioredoxin were similar, whereas APE/ref-1 expression was greater in nuclei. Neither of these markers was predictive of outcome in this series of patients treated with radical radiotherapy. Both proteins showed highly significant elevations in CAIX-positive regions compared to CAIX-negative regions, and there was a nonsignificant trend for this effect to be greater in adenocarcinomas compared to squamous cell carcinomas. Levels of APE/ref-1 decreased with increasing tumor grade, but the expression was similar in CAIX-positive regions of poorly differentiated tumors compared to moderately or well-differentiated tumors. Elevated expression of thioredoxin and APE/ref-1 might promote cancer cell survival in hypoxic microenvironments of cervical carcinomas.

Adult↗

PubMed2004

Outcome and toxicity of postoperative short course adjuvant radiation and chemotherapy following resection of adenocarcinoma of the rectum.

A retrospective review has been performed to assess the outcome and toxicity of post-operative adjuvant therapy of 25 Gy/5 fractions/1 week following resection of stage II and III rectal cancer. Forty patients were treated between August 1992 and May 1995. The ages ranged from 42 to 79 (median 63); 32 were male (80%). At last follow up 32 were alive with 0.9 to 11.3 years of follow-up (median 6.6 years). The 5-year actuarial survival was 76% (95% CI: 62-91%). The local relapse free rate was 73% (95% CI: 58-88). Seven patients experienced grade 3 or 4 early toxicity. Three patients had grade 2 or 3 late toxicity. Although treatment was well tolerated, the local relapse rate observed was high. In view of the changes in surgical and pathological techniques in the last decade, further studies are required to determine the merits or otherwise of postoperative Short Course Adjuvant Radiation.

Adenocarcinoma↗

PubMed2004

The changing costs of radiation treatment for early prostate cancer in Ontario: a comparison between conventional and conformal external beam radiotherapy.

PURPOSE: Prostate cancer represents a large part of the workload for radiation oncology departments in Canada. Recent evidence suggests that conformal external beam radiotherapy improves results. The planning and treatment process for conformal patients requires a greater amount of resources that are in short supply in Ontario. An understanding of these differences is important to provide an accurate estimate of future radiation needs of the province. These differences can be quantified in a cost model that portrays the direct costs of delivering external beam radiotherapy in Ontario. With a developed cost model, a prospective direct cost comparison between standard four field external beam radiotherapy versus conformal radiotherapy in early stage prostate carcinoma was designed. METHODS: Activity based costing has been used to create a model of radiotherapy related costs for prostate cancer. A process map was developed which separated the process in five activities for conventional radiotherapy and six activities for dose escalated conformal radiotherapy. Time was recognized as the important cost driver within each activity. The time required for pre-treatment preparation (CT planning, dosimetry, simulation, and other preparatory work) and actual treatment times were collected prospectively. Treatment times were collected in 414 patients. The annual costs of capital equipment purchase costs and specialized construction of hospital space for radiotherapy equipment were amortized using a 6% discount rate plus the cost of annual maintenance. Indirect costs were not included in this cost analysis. RESULTS: An activity based costing model using time as the primary cost driver reflects the additional costs of conformal over conventional external beam radiotherapy. The costs of single phase and double phase six field conformal therapy with 42 fractions delivered was 7867 Canadian dollars and 8227 Canadian dollars per patient. Four field single phase conformal therapy with 28 fractions costs 5723 Canadian dollars. The cost of conventional radiotherapy over 33 fractions was 3068 Canadian dollars. The majority of the cost differences arose from the cost of the additional time needed for treatment per day as well as the extra fractions per patient when compared to conventionally treated patients. The average treatment times per fraction for six field conformal, four field conformal and four field conventional have the median times of 22.72, 20.63 and 11.07 minutes respectively. Planning costs for conformal radiotherapy were up to three times the cost of conventional therapy. CONCLUSIONS: The direct costs of dose escalated conformal external beam radiotherapy are over 2.5 times that of conventional external beam radiotherapy for early stage prostate cancer. These direct costs are a reflection of the additional capital and human resources needed to provide state-of-the-art radiation therapy in the province of Ontario. Planning for radiation oncology needs should consider the additional costs of conformal external beam radiotherapy.

Costs and Cost Analysis↗

PubMed2003

Impact of chest wall and lung invasion on outcome of stage I-II Hodgkin's lymphoma after combined modality therapy.

PURPOSE: To examine the impact of extranodal chest wall and lung invasion on the prognosis of patients with clinical Stage I-II Hodgkin's lymphoma treated with combined modality therapy. MATERIALS AND METHODS: The outcome of 324 patients with clinical Stage I-II Hodgkin's lymphoma treated with combined modality therapy between 1981 and 1996 was analyzed. Twenty-two patients had chest wall invasion and 40 had invasion of lung parenchyma. The chemotherapy regimens used were ABVD in 182 patients (56%), MOPP/ABV(D) in 45 (14%), MOPP in 86 (27%), and other chemotherapy regimens in 11 patients (3%). This was followed by mantle/mediastinal radiotherapy (RT) in 163 patients (50%), extended-field RT in 135 patients (42%), and infradiaphragmatic RT in 26 patients (8%). The impact of chest wall and lung invasion on local relapse, disease-free survival, cause-specific survival, and overall survival was examined. RESULTS: After a median follow-up of 8.3 years, the 5-year cause-specific and overall survival rate of the entire cohort was 93% and 90%, respectively. Compared with patients with no extranodal involvement, patients with chest wall invasion had significantly worse local control (89% vs. 68%, p = 0.005), disease-free survival (84% vs. 59%, p = 0.016), and cause-specific survival (94% vs. 86%, p = 0.009). Overall survival was also worse among patients with chest wall invasion, but not significantly so (90% vs. 82%, p = 0.10). Among the 16 patients with chest wall invasion but without lung invasion, 7 progressed during treatment or relapsed, 6 with local failure (crude relapse rate 44%, 95% confidence interval [CI] 19-68%), and 5 died (crude death rate 31%, 95% CI 9-54%). After adjusting for other significant prognostic factors, patients with chest wall invasion had significantly worse local control (hazard ratio 2.8, 95% CI 1.2-6.3), disease-free survival (hazard ratio 2.3, 95% CI 1.1-4.8), and cause-specific survival (hazard ratio 2.8, 95% CI 1.1-6.8). Lung invasion was not significantly associated with any of the outcomes assessed. CONCLUSIONS: Chest wall invasion is an adverse prognostic factor among clinical Stage I-II Hodgkin's lymphoma patients treated with combined modality therapy, although we did not find a worse outcome for patients with lung invasion. Efforts to reduce treatment intensity in these patients should be undertaken with caution, recognizing their increased risk of local relapse.

Adolescent↗

PubMed2003

Localized mucosa-associated lymphoid tissue lymphoma treated with radiation therapy has excellent clinical outcome.

PURPOSE: Extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) is a distinct lymphoma with unique clinicopathologic features. We report the clinical outcome of stage I and II MALT lymphoma treated with involved field radiation therapy (RT). PATIENTS AND METHODS: From 1989 to 2000, 103 patients with stage IE and IIE disease were referred. Their median age was 60 years, with a 2:1 female predominance. Presenting sites were stomach (17 patients), orbital adnexa (31 patients), salivary glands (24 patients), thyroid gland (13 patients), and other sites (18 patients). Ninety-three patients received RT--85 received RT alone, and eight received chemotherapy and RT--with a median dose of 30 Gy. The median follow-up time was 5.1 years. RESULTS: A complete response (CR) to RT alone was achieved in 84 of 85 patients. Among CR patients, 14 experienced relapse. Relapse sites were mostly contralateral paired-organ or distant MALT locations and, infrequently, lymph nodes. The crude local control rate with RT was 95.3% (81 of 85 patients). No relapses were observed in patients with stomach or thyroid lymphoma, whereas 14 of 63 patients (22%) experienced relapse in the other sites. The overall 5-year survival rate was 98%, and the disease-free survival rate was 77%. Transformed lymphoma was observed in 14% of patients (two of 14) experiencing relapse. CONCLUSION: Moderate-dose RT achieved excellent local control in localized MALT lymphomas and had curative potential for three fourths of the patients. Gastric and thyroid MALT lymphomas had better outcome, whereas distant failures were common for other sites. Despite relapse, the disease often maintained an indolent course.

Adult↗

PubMed2003

Carbonic anhydrase IX expression, hypoxia, and prognosis in patients with uterine cervical carcinomas.

PURPOSE: Hypoxia is associated with adverse outcome for a number of solid tumors, including cervical carcinomas. Direct pO(2) measurement requires specialized equipment and expertise that is not generally available. Immunohistochemical measurement of intrinsic tissue markers of hypoxia is an alternative approach. Recent studies suggest that carbonic anhydrase IX (CA IX), which is regulated via hypoxia-inducible factor 1, is a useful intrinsic marker of tumor hypoxia. EXPERIMENTAL DESIGN: Biopsies were obtained from 110 patients with locally advanced cervical carcinoma treated with radiotherapy or chemoradiotherapy. Tissue sections were labeled using an immunofluorescence technique and CA IX expression in the viable tumor area measured using a semiautomated fluorescence image analysis technique. Results were compared with direct pO(2) values obtained using an Eppendorf probe and to patient outcome. Intratumoral heterogeneity of CA IX expression was examined in a subgroup of patient who underwent multiple biopsies. RESULTS: The median percentage of tumor area staining for CA IX was 3.56 (range, 0.01-58.85). CA IX staining did not correlate with the Eppendorf pO(2) measurements. Whereas the latter values were predictive of patient outcome, the CA IX levels were not. Measurement of CA IX in multiple biopsies indicated that intratumoral heterogeneity accounted for 41% of the total variance in the data set. CONCLUSIONS: In contrast to some recent studies, we did not find significant associations between CA IX expression and tumor pO(2) levels or patient outcome in locally advanced carcinomas of the cervix. Probable explanations relate to the problems of sampling error using single biopsies and the existence of biological factors other than hypoxia that influence CA IX levels.

Adult↗

PubMed2003

Pretreatment proliferation parameters do not add predictive power to clinical factors in cervical cancer treated with definitive radiation therapy.

PURPOSE: To examine the prognostic value of tumor proliferation measurements in women with carcinoma of the uterine cervix. We report an update of a prospective study focusing on whether pretreatment proliferation parameters are associated with clinical outcome, relative to other established clinical factors. MATERIALS AND METHODS: One hundred and one patients were recruited into the study from years 1991 to 1999. The LI for in vivo bromodeoxyuridine incorporation by the tumor and the potential doubling time (T(pot)) were determined by flow cytometry (fc). LI and its staining pattern were also assessed by immunohistochemistry (ih) using tissue sections. Apoptosis was assessed histologically using morphological criteria. Patients were treated with definitive radiation therapy. RESULTS: A successful fc measurement for LI-fc and T(pot) was possible in 95 patients (94%). The median/mean LI-fc was 6.6/7.6% (range 1.4-36.1%), and for LI-ih, 10.8/11.5%. To date, 43 patients have died of disease, and the median follow-up for alive patients is 6.2 years (range 1.3-9.3 years). Among 88 patients who completely responded to treatment, 40 patients have relapsed (14 pelvic, 23 distant, and 3 pelvic and distant). In univariate analysis, the significant factors for adverse disease-free survival were large tumor size (P = 0.0001), low hemoglobin (P = 0.001), pelvic lymph node status (P = 0.004), stage (P = 0.013), and overall treatment time (P = 0.0008). In multivariate analysis, only tumor size, pelvic lymph node status, and overall treatment time remained significant for disease-free survival. LI-fc, LI-ih, T(pot), ploidy, pattern of bromodeoxyuridine staining, and apoptosis were not significantly associated with clinical outcome in univariate or multivariate analyses. CONCLUSIONS: These mature data indicate that none of the pretreatment proliferation parameters have prognostic significance in the radical radiotherapy of carcinoma of the uterine cervix, despite the significance of overall treatment time for treatment outcome.

Adenocarcinoma↗

PubMed2003

Factors associated with failure to publish large randomized trials presented at an oncology meeting.

CONTEXT: Large clinical trials are the criterion standard for making treatment decisions, and nonpublication of the results of such trials can lead to bias in the literature and contribute to inappropriate medical decisions. OBJECTIVES: To determine the rate of full publication of large randomized trials presented at annual meetings of the American Society of Clinical Oncology (ASCO), quantify bias against publishing nonsignificant results, and identify factors associated with time to publication. DESIGN: Survey of 510 abstracts from large (sample size, > or =200), phase 3, randomized controlled trials presented at ASCO meetings between 1989 and 1998. Trial results were classified as significant (P< or =.05 for the primary outcome measure) or nonsignificant (P>.05 or not reported), and the type of presentation and sponsorship were identified. Subsequent full publication was identified using a search of MEDLINE and EMBASE, completed November 1, 2001; the search was updated in November 2002, using the Cochrane Register of Controlled Trials. Authors were contacted if the searches did not find evidence of publication. MAIN OUTCOME MEASURES: Publication rate at 5 years; time from presentation to full publication. RESULTS: Of 510 randomized trials, 26% were not published in full within 5 years after presentation at the meeting. Eighty-one percent of the studies with significant results had been published by this time compared with 68% of the studies with nonsignificant results (P<.001). Studies with oral or plenary presentation were published sooner than those not presented (P =.002), and studies with pharmaceutical sponsorship were published sooner than studies with cooperative group sponsorship or studies for which sponsorship was not specified (P =.02). These factors remained significant in a multivariable model. The most frequent reason cited by authors for not publishing was lack of time, funds, or other resources. CONCLUSIONS: A substantial number of large phase 3 trials presented at an international oncology meeting remain unpublished 5 years after presentation. Bias against publishing nonsignificant results is a problem even for large randomized trials. Nonpublication breaks the contract that investigators make with trial participants, funding agencies, and ethics boards.

Bias↗

PubMed2003

Costimulation through the inducible costimulator ligand is essential for both T helper and B cell functions in T cell-dependent B cell responses.

Costimulation through the inducible costimulator (ICOS) and its ligand (ICOSL) is essential for T cell-dependent B cell responses, but the cellular and temporal dynamics underlying its in vivo effects are poorly defined. Here we have shown that Icosl(-/-) and Icos(-/-) mice had similar phenotypes and that ICOS-ICOSL costimulation modulated the early but not late phases of IgG1 affinity maturation. Exploiting the adoptive transfer of T or B cells from primed Icosl(-/-) mice, we provided genetic evidence that costimulation through ICOSL was essential for primary but not secondary helper T cell responses and for the control of both T and B cell activities, resulting in T cell-dependent IgG1 production.

Animals↗

PubMed2003

Estimating hypoxic status in human tumors: a simulation using Eppendorf oxygen probe data in cervical cancer patients.

PURPOSE: To define the minimal number of pO(2) measurements, with 90% sensitivity and 90% specificity, needed to categorize cervical tumors as either hypoxic or oxic. METHODS AND MATERIALS: Using Eppendorf oxygen probe data from our ongoing prospective trial, we simulated the measurement of tumor oxygenation with a smaller number of data points in 135 patients with cervical cancer. The hypoxic proportion, defined as the percentage of pO(2) values <5 mm Hg (HP5), was calculated for each tumor. Hypoxic tumors were defined as those with a median HP5 >50%, and tumors with normal oxygen levels as those with a median HP5 < or =50%. A small number of pO(2) measurements were randomly selected from the Eppendorf measurements in each tumor, or per Eppendorf track, and used to define the tumor as hypoxic or oxic. The sensitivity and specificity were calculated, considering the classification as given by the complete set of Eppendorf measurements as the reference standard. RESULTS: The probability of falsely classifying the tumor decreased as the selected number of pO(2) measurements per tumor increased, and at 16 measurements was approximately 10%. Adding additional measurements per tumor beyond 24 improved the ability to classify the tumor accurately only slightly. The probability of falsely classifying the tumor decreased as the pO(2) measurements per track increased. At five measurements per track, the probability of falsely classifying the tumor was approximately 9%. CONCLUSION: Approximately 20 measurements per tumor, or five measurements per track, using the Eppendorf pO(2) histograph, are sufficient to categorize cervical tumors as hypoxic or oxic. The results of this study will serve as a guide for research clinicians in the use of this and other systems in the assessment of tumor oxygenation in humans.

Adenocarcinoma↗

PubMed2003

Dysregulated PTEN-PKB and negative receptor status in human breast cancer.

Recent studies demonstrate that abnormalities in PTEN may be one of the most frequent genetic events observed in human cancers. PTEN dysfunction leads to tumorigenesis through unopposed survival signals mediated via activated protein kinase B (PKB), which may also be associated with hormone-independence. We therefore investigated the relationship between PTEN-PKB and receptor status in human breast cancer. Several molecular variables, including immunohistochemical staining for PTEN, PKB (phosphorylated on ser473), p53 and p21 were evaluated. The p53 gene was sequenced from exons 2-11. Seventy-eight participants in a randomised breast cancer trial served as the cohort for our study. Twenty-eight of 77 (36%) patients' tumours demonstrated absent or reduced PTEN expression; 17 of 78 (22%) tumours over-expressed P-PKB. A significant inverse relationship was observed between reduced PTEN and increased P-PKB expression. Reduced PTEN also correlated with reduced ER or PR expression. None of the molecular variables correlated with survival. ER and PR negative tumours, however, experienced a significantly inferior disease-free survival than other ER/PR status tumours. Immunohistochemical analyses of ER expression in mammary carcinomas arising in PTEN heterozygous knockout mice did not demonstrate a reduction in ER immunoreactivity, in comparison to wild-type mice. Our data demonstrate that the PTEN-PKB pathway is abnormal in approximately 1/3 of lymph node negative breast cancer. Dysregulated PTEN-PKB was also associated with reduced ER/PR expression, but this does not appear to be a simple direct causal relationship. These observations support the contention that dysregulation in PTEN-PKB contributes to disease progression and hormone resistance of human breast cancer.

Aged↗

PubMed2003

Limitation of conventional two dimensional radiation therapy planning in nasopharyngeal carcinoma.

PURPOSE: To assess the adequacy of coverage of gross tumor volume (GTV) with traditional two dimensional (2D) radiation therapy (RT) planning in patients with nasopharyngeal cancer (NPC). MATERIALS AND METHODS: The study comprised 94 of 179 patients treated with definitive RT between 1993 and 1997. The inclusion requirement was the availability of a digitally archived pretreatment magnetic resonance imaging. The digital images were used to record the precise location of the GTV in the sagittal plane. As a separate procedure, sagittal dose distributions for each treatment phase were created by digitizing the simulation field parameters into treatment planning software without knowledge of the GTV. The location of the GTV and dose distribution in the sagittal plane were superimposed on each other and GTV coverage by the 50, 90 and 95% isodose lines determined for each phase of treatment. RESULTS: The 1997 tumour node metastasis (TNM) stage distribution was: 7 (8%) stage I, 16 (16%) stage II, 30 (32%) stage III and 41 (44%) stage IV. Median follow-up was 4.4 years. Median primary dose was 66 Gy. The actuarial 5-year overall survival, disease free survival and local relapse free rates were 88, 54 and 66%, respectively. The GTV was covered by the 50, 90 and 95% isodose lines for all phases of the multiphase plan in only 53, 20 and 9% of patients, respectively. The GTV was more likely to be undercovered in the latter phases of the plan particularly in those patients with advanced T category. CONCLUSION: 2D RT planning has significant limitations in achieving adequate GTV coverage in NPC. We strongly recommend 3D planning using either conformal techniques of dose delivery or intensity modulated radiation therapy for the treatment of these patients.

Adolescent↗

PubMed2003

Loss of p16 expression has prognostic significance in human nasopharyngeal carcinoma.

PURPOSE: p16 is an important inhibitor of cell cycle progression; absence of p16 can thus result in increased cellular proliferation. In nasopharyngeal carcinoma (NPC), absence of p16 has been reported in association with presence of the EBV and pRb. We therefore examined p16, pRb, and EBV-encoded RNA (EBER) expression in biopsy specimens from 84 patients with newly diagnosed NPC, who were treated primarily with curative radiation therapy. Our objective was to determine whether there was a correlation between these parameters and clinical outcome in NPC. EXPERIMENTAL DESIGN: Sections were cut from archival formalin-fixed, paraffin-embedded tumor blocks from NPC patients. p16 and pRb expression were determined using polyclonal and monoclonal antibodies, respectively. The presence of EBV was determined by in situ hybridization for EBER. The percentage of positively staining tumor nuclei was scored for p16 or pRb immunoreactivity. Relative intensity and proportion of cells with EBER signals were also documented. RESULTS: p16 expression was reduced (</=5% positive immunoexpression) in 59 of 84 (70%) NPC samples; in contrast, pRb was observed in all (100%) tumors. EBER signals were detected in 67 of 83 (81%) NPC specimens. There was a weak correlation between EBER presence and loss of p16 (P = 0.1). Using a Cox regression model controlling for known prognostic parameters, such as age, weight loss, and tumor stage, complete absence of p16 expression (0%, i.e., no immunostaining identified throughout the specimen) was associated with an inferior overall survival rate (P = 0.022). In addition, EBER-positive NPC was strongly associated with improved overall survival (P = 0.005) as reported previously (Shi et al., Cancer, 94: 1997, 2002). CONCLUSION: These results provide the first evidence suggesting that inactivation of p16 appears to be a significant predictor for poor overall survival in NPC. Given that reduced p16 expression is observed in the majority of patients with NPC, this indicates that therapeutic strategies targeting the p16 pathway may be a biologically rational approach for NPC. The favorable prognostic value of EBER suggests that future clinical trials with NPC should consider stratifying for EBER status.

Adult↗