Darrell D. Davidson

Prospective Study of Fluorodeoxyglucose–Positron Emission Tomography Imaging of Lymph Node Basins in Melanoma Patients Undergoing Sentinel Node Biopsy

PURPOSE To prospectively compare positron emission tomography (PET) imaging of regional lymph node basins to sentinel node biopsy (SNB) in patients with American Joint Committee on Cancer (AJCC) stage I, II, and III melanoma localized to the skin. METHODS Patients with cutaneous melanoma with Breslows depth greater than 1 mm (AJCC T2-4N0M0) or localized regional cutaneous recurrence (TxN2bM0) underwent whole-body imaging of glucose metabolism with fluorodeoxyglucose (FDG) PET followed by SNB. PET scans were interpreted in a blinded fashion and compared with histologic analyses of SNB specimens and clinical follow-up examination. Nodal tumor volumes were estimated. RESULTS Eighty-nine lymph node basins were evaluated by FDG-PET and SNB in 70 assessable patients. Eighteen patients (25.7%) had lymph node metastases at the time of FDG-PET imaging: 17 proved by SNB (24.3%) and one by follow-up examination (1.4%). Median tumor volume in positive sentinel node basins was 4.3 mm3 (range, 0.07 to 523 mm3). Sensitivity of SNB for detection of occult regional lymph node metastases was 94.4%, specificity was 100%, positive predictive value (PPV) was 100%, and negative predictive value (NPV) was 98.6%. Sensitivity of FDG-PET was 16.7%, specificity was 95.8%, PPV was 50%, and NPV was 81.9%. At a median follow-up duration of 16.6 months, seven patients (10%) developed recurrent disease. PET predicted one recurrence (14.3%) in a node basin missed by SNB. CONCLUSION FDG-PET is an insensitive indicator of occult regional lymph node metastases in patients with melanoma because of the minute tumor volumes in this population. FDG-PET does not have a primary role for staging regional nodes in patients with clinically localized melanoma.

Molecular pathology of lung cancer: key to personalized medicine.

The majority of lung adenocarcinoma patients with epidermal growth factor receptor- (EGFR) mutated or EML4–ALK rearrangement-positive tumors are sensitive to tyrosine kinase inhibitors. Both primary and acquired resistance in a significant number of those patients to these therapies remains a major clinical problem. The specific molecular mechanisms associated with tyrosine kinase inhibitor resistance are not fully understood. Clinicopathological observations suggest that molecular alterations involving so-called ‘driver mutations’ could be used as markers that aid in the selection of patients most likely to benefit from targeted therapies. In this review, we summarize recent developments involving the specific molecular mechanisms and markers that have been associated with primary and acquired resistance to EGFR-targeted therapy in lung adenocarcinomas. Understanding these mechanisms may provide new treatment avenues and improve current treatment algorithms.

Inefficacy of F‐18 fluorodeoxy‐D‐glucose‐positron emission tomography scans for initial evaluation in early‐stage cutaneous melanoma

The purpose of the current study was to determine the sensitivity and specificity of initial F‐18 fluorodeoxy‐D‐glucose‐positron emission tomography (FDG‐PET) scanning for detection of occult lymph node and distant metastases in patients with early‐stage cutaneous melanoma.

Staging and reporting of urothelial carcinoma of the urinary bladder

Significant progress has been made in the standardization of bladder neoplasm classification and reporting. Accurate staging using the American Joint Committee on Cancer/International Union Against Cancer (AJCC/UICC) TNM system is essential for patient management, and has been reinforced by clinical evidence in recent years. It is now recognized that ‘superficial’ bladder carcinomas are a heterogenous group of tumors with diverse biological and clinical manifestations. The term ‘superficial,’ therefore, is no longer used for bladder tumor nomenclature. Recognition of diagnostic pitfalls associated with lamina propria invasion is critical for the evaluation of bladder tumor specimens. Neither the 1973 nor the 2004 WHO grading system appears to be useful for predicting the clinical outcome of invasive urothelial carcinoma. This review will discuss recent progress and controversial issues on the staging and substaging of bladder carcinomas. Essential elements for handling and reporting of bladder tumor specimens will also be discussed.

Evidence for Common Clonal Origin of Multifocal Lung Cancers

BACKGROUND Lung cancer is the most common cause of cancer death in the United States. Multiple anatomically separate but histologically similar lung tumors are often found in the same patient. The clonal origin of multiple lung tumors is uncertain. METHODS We analyzed 70 lung tumors from 30 patients (23 females and seven males) who underwent surgical resection for lung epithelial tumors, of whom 26 had non-small cell carcinomas and four had carcinoid/atypical carcinoid tumors. All patients had multiple tumors (two to five) involving one or both lungs. Genomic DNA was extracted from paraffin-embedded tissue sections using laser capture microdissection and analyzed for loss of heterozygosity, TP53 mutations, and X-chromosome inactivation status. The percentage (95% confidence interval [CI]) of patients in whom there were concordant patterns of genetic alteration was calculated. RESULTS All 30 case subjects showed loss of heterozygosity (LOH) in at least one and at most four of the six polymorphic microsatellite markers. Completely concordant LOH patterns between synchronous and metachronous cancers in individual patients were seen in 26 (87%) of 30 informative patients (95% CI = 75% to 99%). Identical point mutations were present in eight of 10 patients who exhibited TP53 mutation by sequencing. Tumors in 18 (78%) of 23 female patients (95% CI = 67% to 98%) showed identical X-chromosome inactivation patterns. Combining the results of LOH studies, TP53 mutation screening analyses, and X-chromosome inactivation data, we demonstrated that the multiple separate tumors in 23 (77%) of 30 patients (95% CI = 62% to 92%) had identical genetic changes, consistent with monoclonal origin of the separate tumors. CONCLUSIONS Our data indicate that the great majority of multifocal lung cancers have a common clonal origin and that multifocality in lung cancer represents local and regional intrapulmonary metastasis.

Sentinel lymph node biopsy for melanoma: experience with 234 consecutive procedures.

Sentinel lymph node biopsy is increasingly used to identify occult metastases in regional lymph nodes of patients with melanoma. Selection of patients for sentinel lymph node biopsy and subsequent lymphadenectomy is an area of debate. The purpose of this study was to describe a large clinical series of these biopsies for cutaneous melanoma and to identify patients most likely to gain useful clinical information from sentinel lymph node biopsy. The Indiana University Melanoma Program computerized database was queried to identify all patients who underwent this procedure for clinically localized cutaneous melanoma. It was performed using preoperative technetium Tc 99m lymphoscintigraphy and isosulfan blue dye. Pertinent demographic, surgical, and histopathologic data were recorded. Univariate and multivariate logistic regression and classification table analyses were performed to identify clinical variables associated with sentinel node and nonsentinel node positivity. In total, 234 biopsy procedures were performed to stage 291 nonpalpable regional lymph node basins. Mean Breslow’s thickness was 2.30 mm (2.08 mm for negative sentinel lymph node biopsy, 3.18 mm for positive). The mean number of sentinel nodes removed was 2.17 nodes per basin (range, 1 to 8). Forty-seven of 234 melanomas (20.1 percent) and 50 of 291 basins (17.2 percent) had a positive biopsy. Positivity correlated with AJCC tumor stage: T1, 3.6 percent; T2, 8.1 percent; T3, 27.4 percent; T4, 44 percent. By univariate logistic regression, Breslow’s thickness (p = 0.003, continuous variable), ulceration (p = 0.003), mitotic index ≥ 6 mitoses per high power field (p = 0.008), and Clark’s level (p = 0.04) were significantly associated with sentinel lymph node biopsy result. By multivariate analysis, only Breslow’s thickness (p = 0.02), tumor ulceration (p = 0.02), and mitotic index (p = 0.02) were significant predictors of biopsy positivity. Classification table analysis showed the Breslow cutpoint of 1.2 mm to be the most efficient cutpoint for sentinel lymph node biopsy result (p = 0.0004). Completion lymphadenectomy was performed in 46 sentinel node-positive patients; 12 (26.1 percent) had at least one additional positive nonsentinel node. Nonsentinel node positivity was marginally associated with the presence of multiple positive sentinel nodes (p = 0.07). At mean follow-up of 13.8 months, four of 241 sentinel node-negative basins demonstrated same-basin recurrence (1.7 percent). Sentinel lymph node biopsy is highly reliable in experienced hands but is a low-yield procedure in most thin melanomas. Patients with melanomas thicker than 1.2 mm or with ulcerated or high mitotic index lesions are most likely to have occult lymph node metastases by sentinel lymph node biopsy. Completion therapeutic lymphadenectomy is recommended after positive biopsy because it is difficult to predict the presence of positive nonsentinel nodes.

Urothelial dysplasia and other flat lesions of the urinary bladder: clinicopathologic and molecular features

The 2004 World Health Organization classification system for urothelial neoplasia classifies flat-related preneoplastic lesions as urothelial hyperplasia (flat and papillary), reactive urothelial atypia, urothelial atypia of unknown significance, urothelial dysplasia (low-grade intraurothelial neoplasia), and urothelial carcinoma in situ (high-grade intraurothelial neoplasia). Each lesion is defined with precise nomenclature and strict morphologic criteria. In many cases, morphologic features alone suffice for diagnosis. Other cases may require a panel of immunohistochemical antibodies consisting of cytokeratin 20, p53, and CD44 for diagnosis. Recent molecular studies have provided further insight into the premalignant potential of these urothelial lesions. Herein, we present a review of flat urothelial lesions of the urinary bladder as defined by the 2004 World Health Organization classification with focus on the clinicopathologic, immunohistochemical, and molecular features.

The origins of urothelial carcinoma

It is now widely believed that there are two major pathways for urothelial carcinogenesis. One pathway usually involves mutation of FGF receptor 3 and gives rise to low-grade papillary tumors that frequently recur but seldom invade. By contrast, high-grade urothelial malignancies, including high-grade papillary urothelial carcinoma and urothelial carcinoma in situ (CIS) usually exhibit deletions or mutations of TP53. Urothelial CIS is the most likely precursor of high-grade invasive bladder cancer. It is a ‘flat lesion’ that may be relatively inconspicuous at cystoscopy, or even endoscopically undetectable. The clinical hazards associated with this elusive and biologically dangerous neoplasm have been increasingly well documented since the original studies by Melicow in 1952. Primary or secondary urothelial dysplasia is even more challenging to detect and diagnose than CIS. It is theorized that dysplasia may antedate the onset of CIS, but support for the putative progression of dysplasia to CIS is found in fewer than 20% of cases. Since many benign urothelial changes may resemble CIS at cystoscopy, in biopsies and even with molecular profiling, care must be exercised when making a diagnosis of CIS. For patients whose screening tests are worrisome for the presence of premalignant urothelial disease, newer bladder imaging modalities, including Raman spectral imaging and optical coherence tomography, may enable improved biopsy site selection. In this article, we discuss the above-noted topics, as well as other related issues, such as the possible role of papillary urothelial hyperplasia as a preneoplastic lesion and the roles of cancer stem cells and field cancerization in urothelial carcinogenesis.

Laser-assisted microdissection in translational research: Theory, technical considerations, and future applications

Molecular profiling already exerts a profound influence on biomedical research and disease management. Microdissection technologies contribute to the molecular profiling of diseases, enabling investigators to probe genetic characteristics and dissect functional physiology within specific cell populations. Laser-capture microdissection (LCM), in particular, permits collation of genetic, epigenetic, and gene expression differences between normal, premalignant, and malignant cell populations. Its selectivity for specific cell populations promises to greatly improve the diagnosis and management of many human diseases. LCM has been extensively used in cancer research, contributing to the understanding of tumor biology by mutation detection, clonality analysis, epigenetic alteration assessment, gene expression profiling, proteomics, and metabolomics. In this review, we focus on LCM applications for DNA, RNA, and protein analysis in specific cell types and on commercially available LCM platforms. These analyses could clinically be used as aids to cancer diagnosis, clinical management, genomic profile studies, and targeted therapy. In this review, we also discuss the technical details of tissue preparation, analytical yields, tissue selection, and selected applications using LCM.

Radial distance of extraprostatic extension measured by ocular micrometer is an independent predictor of prostate-specific antigen recurrence: A new proposal for the substaging of pT3a prostate cancer.

Extraprostatic extension is an unfavorable prognostic factor for prostate cancer. Consequently, it has been assigned to pT3a in the current 2002 tumor, lymph node, metastasis staging system. The aim of our study is to analyze the extent of extraprostatic extension by 8 quantitative methods and to determine which is best for substaging of pT3a tumors. We studied 83 patients with extraprostatic extension after radical prostatectomy for clinically localized prostatic adenocarcinoma. The extent of extraprostatic extension was evaluated using 8 quantitative methods. Univariate and multivariate analyses were performed to determine which measurement best predicts prostate-specific antigen (PSA) recurrence. In the univariate analysis, the radial distance of extraprostatic tumor measured by ocular micrometer was associated with PSA recurrence (P=0.02). No significant association was observed between PSA recurrence and other measurements of extraprostatic extension, including focal versus established extraprostatic extension using Epsteins criterion, focal versus established extraprostatic extension using Wheelers modified criterion, the number of extraprostatic neoplastic glands, unilateral versus bilateral involvement, circumferential length of extraprostatic tumor, unifocal versus multifocal involvement, and volume of extraprostatic tumor. In the multivariate analysis, radial distance remained an independent predictor of PSA recurrence (hazard ratio, 2.4; 95% confidence interval, 1.12-5.01; P=0.02). The radial distance of the extraprostatic extension measured by ocular micrometer is an independent prognostic factor for pT3 prostate cancer. Two-year and 4-year PSA recurrence-free survival was 62% and 35%, respectively, for those patients with radial distance <0.75 mm, as compared with 35% and 18%, respectively, for those with radial distance ≥0.75 mm. We recommend reporting this parameter routinely for radical prostatectomy specimens. The strength of its prognostic value for PSA recurrence makes it a potential criterion for incorporation into a future tumor, lymph node, metastasis staging system.