Faculty Bibliography

Although telepathology (TP) has not been widely implemented for primary frozen section diagnoses, interest in its use is growing as we move into an age of increasing sub-specialization and centralization of pathology services. University Health Network (UHN) is a 3-site academic institution in downtown Toronto. The pathology department is consolidated at its Toronto General Hospital (TGH) site. The Toronto Western Hospital (TWH), located 1 mile to west of TGH, has no on-site pathologist and generates 5-10 frozen section cases per week. Over 95% of these frozen sections are submitted by neurosurgeons, in most cases to confirm the presence of lesional tissue and establish a tissue diagnosis. In 2004, we implemented a robotic microscopy (RM) TP system to cover these frozen sections. In 2006, we changed to a virtual slide (VS) TP system. Between November 2004 and September 2006, 350 primary frozen section diagnoses were made by RM. An additional 633 have been reported by VS TP since October 2006, giving a total of 983 frozen sections from 790 patients. Eighty-eight percent of these cases have been single specimens with total turnaround times averaging 19.98 and 15.68 minutes per case by RM and VS TP, respectively (P < 0.0001). Pathologists required an average of 9.65 minutes to review a slide by RM. This decreased 4 fold to 2.25 minutes following the change to VS TP (P < 0.00001). Diagnostic accuracy has been 98% with both modalities and our overall deferral rate has been 7.7%. Mid-case technical failure has occurred in 3 cases (0.3%) resulting in a delay where a pathologist went to TWH to report the frozen section. Discrepant cases have typically involved minor interpretive errors related to tumor type. None of our discrepant TP diagnoses have had clinical impact to date. We have found TP to be reliable and accurate for frozen section diagnoses. In addition to its superior speed and image quality, the VS approach readily facilitates consultation with colleagues on difficult cases. As a result, there has been greater overall pathologist satisfaction with VS TP.

Catalytic deoxygenation of epoxides and diols is underdeveloped. This reaction is appealing in the context of making value-added organics from biomass. Methyltrioxorhenium (MTO) catalyzes the conversion of epoxides and vicinal diols to olefins with dihydrogen (H(2)) as the reductant under reasonably mild conditions (150 degrees C and 80-300 psi). The only reaction byproduct is water. The reaction is selective for cis cyclic diols, signaling a mechanism of alkene extrusion from a coordinated epoxide via a metallaoxetane intermediate.

Tumour hypoxia promotes the accumulation of the otherwise oxygen-labile hypoxia-inducible factor (HIF)-alpha subunit whose expression is associated with cancer progression, poor prognosis and resistance to conventional radiation and chemotherapy. The oxygen-dependent degradation of HIF-alpha is carried out by the von Hippel-Lindau (VHL) protein-containing E3 that directly binds and ubiquitylates HIF-alpha for subsequent proteasomal destruction. Thus, the cellular proteins involved in the VHL-HIF pathway have been recognized as attractive molecular targets for cancer therapy. However, the various compounds designed to inhibit HIF-alpha or HIF-downstream targets, although promising, have shown limited success in the clinic. In the present study, we describe the bioengineering of VHL protein that removes the oxygen constraint in the recognition of HIF-alpha while preserving its E3 enzymatic activity. Using speckle variance-optical coherence tomography (sv-OCT), we demonstrate the dramatic inhibition of angiogenesis and growth regression of human renal cell carcinoma xenografts upon adenovirus-mediated delivery of the bioengineered VHL protein in a dorsal skin-fold window chamber model. These findings introduce the concept and feasibility of 'bio-tailored' enzymes in the treatment of HIF-overexpressing tumours.

Tumor hypoxia is associated with disease progression, resistance to conventional cancer therapies and poor prognosis. Hypoxia, by largely unknown mechanisms, leads to deregulated accumulation of and signaling via receptor tyrosine kinases (RTKs) that are critical for driving oncogenesis. Here, we show that hypoxia or loss of von Hippel-Lindau protein--the principal negative regulator of hypoxia-inducible factor (HIF)--prolongs the activation of epidermal growth factor receptor that is attributable to lengthened receptor half-life and retention in the endocytic pathway. The deceleration in endocytosis is due to the attenuation of Rab5-mediated early endosome fusion via HIF-dependent downregulation of a critical Rab5 effector, rabaptin-5, at the level of transcription. Primary kidney and breast tumors with strong hypoxic signatures show significantly lower expression of rabaptin-5 RNA and protein. These findings reveal a general role of the oxygen-sensing pathway in endocytosis and support a model in which tumor hypoxia or oncogenic activation of HIF prolongs RTK-mediated signaling by delaying endocytosis-mediated deactivation of receptors.

Although breast needle core biopsy (NCB) is now a standard diagnostic procedure in the triple assessment of screen-detected breast lesions, data on the false-positive diagnoses of malignancy (malignant NCB 'B5' with normal/benign surgery) are lacking. In this study, we have studied a large series of NCBs (101,440) to assess the causes and pitfalls resulting in false-positive NCB diagnoses and to evaluate their impact on patients' management in the screening service. Our results showed that of 40,395 malignant NCBs reported during the period of this study, 174 NCBs are considered as false-positives (0.43%; (95% confidence interval [CI]=0.37-0.49%)). However, on review, 165 cases (95%) were found to be the result of true removal of the whole lesion in the core with subsequent negative excision biopsy samples (true-positive NCBs). This may reflect sampling of small screen detected lesions and the use of larger core biopsies at assessment. The remaining 9 cases were considered as true false-positive cores, giving a false-positive rate of 0.02% (95% CI=0.01-0.04%). Analysis of these 9 cases showed that 8 cases, originally diagnosed as DCIS, were classified as borderline lesions or lesions of uncertain malignant potential after surgical excision. The classification and management of such borderline lesions remains controversial and diagnostic surgical excision is usually the optimum management. One case was the result of pathological misinterpretation of fat necrosis as invasive carcinoma. This was the only case that resulted in a significant over-management of the patient. In conclusion, our results showed that the true false-positive rate of NCB is extremely rare. Significant over-management of screen-detected breast lesions as a result of false-positive NCB may be considered almost nil.

UNLABELLED:Although invasive ductal (IDC) and lobular (ILC) breast carcinomas are well characterised in the literature, the biological and clinical significance of mixed tumours with both ductal and lobular components has not been investigated. In the current study, we have examined a well-characterised series of breast carcinoma with a long term follow-up that comprised 140 mixed tumours, 2170 IDC and 380 pure ILC. RESULTS:Mixed tumours constituted 3.6% of all cases. The majority (59%) of the mixed tumours were grade 2 compared to 33% in IDC and 88% in ILC. Positive lymph nodes (LN) were found in 41% and definite vascular invasion (VI) in 26% of the cases. DCIS was detected in 123 (89%) and LCIS in 43 (31%) (both DCIS and LCIS were found in 39 cases). The majority of tumours were predominantly (>50 of tumour area) of ductal type (57%). When compared to pure IDC, mixed tumours showed an association with lower grade, ER positivity and lower frequency of development of distant metastases. When compared to pure ILC, mixed tumours showed an association with higher grade, positive LN metastasis, VI and development of regional metastasis. After adjustment for grade most of these differences were no longer apparent. There was an association between histologic type of carcinoma in LN metastasis and the predominant histologic type of the primary tumour. Mixed tumours showed metastatic patterns similar to that of ILC with frequent metastasis to bone. No clinically meaningful differences in survival were found between these mixed carcinomas and pure IDC or ILC of the breast or between mixed tumours with predominantly ductal or lobular phenotype.

p53 mutations are rarely detected in clear cell renal cell carcinoma (CCRCC), but, paradoxically, these tumors remain highly resistant to chemotherapy and death receptor-induced death. Here, we show that the accumulation of hypoxia-inducible factor 2alpha (HIF2alpha), a critical oncogenic event in CCRCC following the loss of von Hippel-Lindau (VHL) tumor suppressor protein, leads to Hdm2-mediated suppression of p53. Primary CCRCC specimens exhibiting strong hypoxic signatures show increased levels of activated nuclear phospho-Hdm2(Ser(166)), which is concomitant with low p53 expression. The abrogation of Hdm2-p53 interaction using the small-molecule Hdm2 inhibitor nutlin-3 or the downregulation of HIF2alpha via HIF2alpha-specific short hairpin RNA or wild-type VHL reconstitution restores p53 function and reverses the resistance of CCRCC cells to Fas-mediated and chemotherapy-induced cell death. These findings unveil a mechanistic link between HIF2alpha and p53 and provide a rationale for combining Hdm2 antagonists with chemotherapy for the treatment of CCRCC.

Although telepathology (TP) has not been widely implemented for primary frozen section diagnoses, interest in its use is growing as we move into an age of increasing subspecialization and centralization of pathology services. University Health Network is a 3-site academic institution in downtown Toronto. The pathology department is consolidated at its Toronto General Hospital (TGH) site. The Toronto Western Hospital (TWH), located 1 mile to west of TGH, has no on-site pathologist, and generates 5 to 10 frozen section cases per week. More than 95% of these frozen sections are submitted by neurosurgeons, in most cases to confirm the presence of lesional tissue and establish a tissue diagnosis. In 2004, we implemented a robotic microscopy (RM) TP system to cover these frozen sections. In 2006, we changed to a virtual slide (VS) TP system. Between November 2004 and September 2006, 350 primary frozen section diagnoses were made by RM. An additional 633 have been reported by VS TP since October 2006, giving a total of 983 frozen sections from 790 patients. Of these cases, 88% have been single specimens with total turnaround times averaging 19.98 and 15.68 minutes per case by RM and VS TP, respectively (P < .0001). Pathologists required an average of 9.65 minutes to review a slide by RM. This decreased 4-fold to 2.25 minutes after the change to VS TP (P < .00001). Diagnostic accuracy has been 98% with both modalities, and our overall deferral rate has been 7.7%. Midcase technical failure has occurred in 3 cases (0.3%) resulting in a delay, where a pathologist went to TWH to report the frozen section. Discrepant cases have typically involved minor interpretive errors related to tumor type. None of our discrepant TP diagnoses has had clinical impact to date. We have found TP to be reliable and accurate for frozen section diagnoses. In addition to its superior speed and image quality, the VS approach readily facilitates consultation with colleagues on difficult cases. As a result, there has been greater overall pathologist satisfaction with VS TP.

PURPOSE/OBJECTIVE:To develop a multi-parametric model suitable for prospectively identifying prostate cancer in peripheral zone (PZ) using magnetic resonance imaging (MRI). MATERIALS AND METHODS/METHODS:Twenty-five radical prostatectomy patients (median age, 63 years; range, 44-72 years) had T2-weighted, diffusion-weighted imaging (DWI), T2-mapping, and dynamic contrast-enhanced (DCE) MRI at 1.5 Tesla (T) with endorectal coil to yield parameters apparent diffusion coefficient (ADC), T2, volume transfer constant (K(trans)) and extravascular extracellular volume fraction (v(e)). Whole-mount histology was generated from surgical specimens and PZ tumors delineated. Thirty-eight tumor outlines, one per tumor, and pathologically normal PZ regions were transferred to MR images. Receiver operating characteristic (ROC) curves were generated using all identified normal and tumor voxels. Step-wise logistic-regression modeling was performed, testing changes in deviance for significance. Areas under the ROC curves (A(z)) were used to evaluate and compare performance. RESULTS:The best-performing single-parameter was ADC (mean A(z) [95% confidence interval]: A(z,ADC): 0.689 [0.675, 0.702]; A(z,T2): 0.673 [0.659, 0.687]; A(z,Ktrans): 0.592 [0.578, 0.606]; A(z,ve): 0.543 [0.528, 0.557]). The optimal multi-parametric model, LR-3p, consisted of combining ADC, T2 and K(trans). Mean A(z,LR-3p) was 0.706 [0.692, 0.719], which was significantly higher than A(z,T2), A(z,Ktrans), and A(z,ve) (P < 0.002). A(z,LR-3p) tended to be greater than A(z,ADC), however, this result was not statistically significant (P = 0.090). CONCLUSION/CONCLUSIONS:Using logistic regression, an objective model capable of mapping PZ tumor with reasonable performance can be constructed.