Prognostic markers for colorectal cancer: estimating ploidy and stroma.

Background: We report here the prognostic value of ploidy and digital tumour-stromal morphometric analyses using material from 2624 patients with early stage colorectal cancer (CRC). Patients and methods: DNA content (ploidy) and stroma-tumour fraction were estimated using automated digital imaging systems and DNA was extracted from sections of formalin-fixed paraffin-embedded (FFPE) tissue for analysis of microsatellite instability. Samples were available from 1092 patients recruited to the QUASAR 2 trial and two large observational series (Gloucester, n = 954; Oslo University Hospital, n = 578). Resultant biomarkers were analysed for prognostic impact using 5-year cancer-specific survival (CSS) as the clinical end point. Results: Ploidy and stroma-tumour fraction were significantly prognostic in a multivariate model adjusted for age, adjuvant treatment, and pathological T-stage in stage II patients, and the combination of ploidy and stroma-tumour fraction was found to stratify these patients into three clinically useful groups; 5-year CSS 90% versus 83% versus 73% [hazard ratio (HR) = 1.77 (95% confidence interval (95% CI): 1.13-2.77) and HR = 2.95 (95% CI: 1.73-5.03), P < 0.001]. Conclusion: A novel biomarker, combining estimates of ploidy and stroma-tumour fraction, sampled from FFPE tissue, identifies stage II CRC patients with low, intermediate or high risk of CRC disease specific death, and can reliably stratify clinically relevant patient sub-populations with differential risks of tumour recurrence and may support choice of adjuvant therapy for these individuals.

Overexpression of integrin α11 induces cardiac fibrosis in mice.

AIM: To understand the role of the collagen-binding integrin α11 in vivo, we have used a classical approach of creating a mouse strain overexpressing integrin α11. A transgenic mouse strain overexpressing α11 in muscle tissues was analysed in the current study with special reference to the heart tissue. METHODS: We generated and phenotyped integrin α11 transgenic (TG) mice by echocardiography, magnetic resonance imaging and histology. Wild-type (WT) mice were subjected to aortic banding (AB) and the expression of integrin α11 was measured in flow cytometry-sorted cardiomyocytes and non-myocytes. RESULTS: TG mice developed left ventricular concentric hypertrophy by 6 months, with increased collagen deposition and reactivation of mRNA encoding foetal genes associated with cardiovascular pathological remodelling compared to WT mice. Masson's trichrome staining revealed interstitial fibrosis, confirmed additionally by magnetic resonance imaging and was found to be most prominent in the cardiac septum of TG but not WT mice. TG hearts expressed increased levels of transforming growth factor-ß2 and transforming growth factor-ß3 and upregulated smooth muscle actin. Macrophage infiltration coincided with increased NF-κB signalling in TG but not WT hearts. Integrin α11 expression was increased in both cardiomyocytes and non-myocyte cells from WT AB hearts compared to sham-operated animals. CONCLUSION: We report for the first time that overexpression of integrin α11 induces cardiac fibrosis and left ventricular hypertrophy. This is a result of changes in intracellular hypertrophic signalling and secretion of soluble factors that increase collagen production in the heart.

Assessment of DNA Ploidy in the ProMisE molecular subgroups of endometrial cancer.

OBJECTIVE: We sought to determine whether DNA ploidy correlates with the four molecular subgroups of endometrial carcinoma (EC) as determined using ProMisE (Proactive Molecular Risk Classifier for Endometrial Cancer). METHODS: 90 cases of EC previously characterized by clinicopathological parameters, outcomes, and ProMisE molecular subgroup (POLE EDM, MMR-D, p53 wt or p53 abn) were assessed for DNA ploidy using image cytometry. Associations of ploidy with traditional clinicopathological parameters were also tested. RESULTS: Abnormal DNA ploidy status differed amongst the ProMisE groups (p<0.001) and was found in 80.9% (17/21) of p53 abn, 37.0% (10/27) of p53 wt, 28.6% (4/14) of POLE EDM and 14.3% (4/28) of MMR-D. Abnormal DNA content was significantly associated with lower BMI (p=0.034) and grade 3 tumors (p=0.001). In the entire cohort, abnormal DNA content was significantly associated with worse progression free survival (p=0.0094) but not disease specific survival (p=0.249) or overall survival (p=0.187). When examining ploidy within each of the ProMisE groups, abnormal DNA content correlated with worse overall survival (p=0.041) and progression free survival (p=0.011) in the MMR-D group. No statistically significant relationship was seen in the remaining 3 groups. CONCLUSION: Abnormal DNA ploidy status did correlate with the molecular subgroups of EC; abnormal DNA content was seen in the large majority of p53 abn cases. Abnormal ploidy however was also seen in smaller numbers in the p53 wt, POLE EDM and MMR-D groups; therefore abnormal DNA content was not a specific marker for any one molecular group. The addition of ploidy to the ProMisE molecular categories conferred additional prognostic value within the MMR-D group, which merits further study.

DNA ploidy in curettage specimens identifies high-risk patients and lymph node metastasis in endometrial cancer.

BACKGROUND: Preoperative risk stratification is essential in tailoring endometrial cancer treatment, and biomarkers predicting lymph node metastasis and aggressive disease are aspired in clinical practice. DNA ploidy assessment in hysterectomy specimens is a well-established prognostic marker. DNA ploidy assessment in preoperative curettage specimens is less studied, and in particular in relation to the occurrence of lymph node metastasis. METHODS: Curettage image cytometry DNA ploidy in relation to established clinicopathological variables and outcome was investigated in 785 endometrial carcinoma patients prospectively included in the MoMaTEC multicentre trial. RESULTS: Diploid curettage status was found in 72.0%, whereas 28.0% were non-diploid. Non-diploid status significantly correlated with traditional aggressive postoperative clinicopathological features, and was an independent predictor of lymph node metastasis among FIGO stage I-III patients in multivariate analysis (OR 1.94, P=0.033). Non-diploid status was related to shorter disease-specific survival (5-year DSS of 74.4% vs 88.8% for diploid curettage, P<0.001). When stratifying by FIGO stage and lymph node status, the prognostic effect remained. However, in multivariate regression analysis, preoperative histological risk classification was a stronger predictor of DSS than DNA ploidy. CONCLUSIONS: Non-diploid curettage is significantly associated with aggressive clinicopathological phenotype, lymph node metastasis, and poor survival in endometrial cancer. The prognostic effect was also observed among subgroups with (presumably) less aggressive traits, such as low FIGO stage and negative lymph node status. Our results indicate curettage DNA ploidy as a possible supplement to existing parameters used to tailor surgical treatment.

Prognostic impact of genomic instability in colorectal cancer.

BACKGROUND: The prognostic impact of an indication of chromosomal instability (CIN) is evaluated in a consecutive series of 952 colorectal cancer patients treated at Aker University Hospital, Norway, during 1993-2003. Microsatellite instability (MSI) in this case series has recently been reported and made it possible to find the co-occurrence and compare the prognostic significance of CIN and MSI. METHODS: Data sets for overall survival (OS; n=855) and time to recurrence (TTR; n=579) were studied. To reveal CIN we used automated image cytometry (ICM). Non-diploid histograms were taken as indicative of the presence of CIN. PCR-based measures of MSI in this material have already been described. RESULTS: As with MSI, CIN was found to be an independent predictor of early relapse and death among stage II patients (TTR: n=278: HR 2.19 (95% CI: 1.35-3.55), P=0.002). Of the MSI tumours (16%), 71% were found to be DNA diploid, 21% were DNA tetraploid and 8% were DNA aneuploid. Among microsatellite stable tumours, 24% were DNA diploid, 15% were DNA tetraploid and 61% were DNA aneuploid. CONCLUSION: For patients presenting with stage II disease, genomic instability as detected by DNA image cytometry has the potential to provide a useful biomarker for relapse and cancer-related death following surgery with curative intent.

Flotillins as regulators of ErbB2 levels in breast cancer.

Amplification and overexpression of the receptor tyrosine kinase ErbB2 occur in up to 30% of human breast cancers, and high ErbB2 levels are correlated with poor prognosis for breast cancer patients. In contrast to the epithelial growth factor receptor (ErbB1), ErbB2 is not downregulated by ligand-induced mechanisms. Here we show that flotillins are involved in the stabilization of ErbB2 at the plasma membrane. In SKBR3 breast cancer cells and breast cancer tissue, a positive correlation between flotillin and ErbB2 expression levels could be demonstrated. Moreover, the tissue microarray analyses of biopsies from 194 patients diagnosed with carcinomas of the breast showed that flotillin-2 emerged as a potential predictor of prognosis in breast cancer. Depletion of flotillin-1 and flotillin-2 leads to internalization and degradation of ErbB2. Furthermore, flotillin-1 and -2 were found to be in a molecular complex with ErbB2 and Hsp90. The depletion of one of these proteins results in disruption of this complex, followed by destabilization of ErbB2 at the membrane, and its internalization and degradation. As a consequence, ErbB2-triggered downstream signalling is inhibited. Our data demonstrate a novel mechanism for interfering with ErbB2 signalling, which potentially can have clinical impact.

Prognostic importance of DNA ploidy and DNA index in stage I and II endometrioid adenocarcinoma of the endometrium.

BACKGROUND: We evaluated the prognostic importance of DNA ploidy in stage I and II endometrioid adenocarcinoma (EAC) of the endometrium with a focus on DNA index. PATIENTS AND METHODS: High-resolution DNA ploidy analysis was carried out in tumor material from 937 consecutive patients with International Federation of Gynecology and Obstetrics (FIGO) stage I and II EAC of the endometrium. RESULTS: Patients with diploid (N = 728), aneuploid tumor with DNA index ≤ 1.20 (N = 118), aneuploid tumors with DNA index >1.20 (N = 39) and tetraploid tumor (N = 52) had 5-year recurrence rates 8%, 14%, 20% and 12%, respectively. Patients with aneuploid tumor with DNA index >1.20 had a poorer 5-year progression-free survival (67%) and overall survival (72%) compared with the patients with aneuploid tumor with DNA index ≤ 1.20 (81% and 89%, respectively). Aneuploid tumors with DNA index ≤ 1.20 relapsed mainly in the vagina and pelvis, whereas aneuploid tumors with DNA index >1.20 relapsed predominantly outside pelvis. CONCLUSIONS: The recurrence risk for the patients with aneuploid tumor is higher than the patients with diploid tumor in EAC of the endometrium. Based on DNA index with cut-off 1.20, aneuploid tumors can be separated into two subgroups with different recurrence pattern and survival.

Comparison of nuclear texture analysis and image cytometric DNA analysis for the assessment of dysplasia in Barrett's oesophagus.

BACKGROUND: Dysplasia is a marker of cancer risk in Barrett's oesophagus (BO), but this risk is variable and diagnosis is subject to inter-observer variability. Cancer risk in BO is increased when chromosomal instability is present. Nucleotyping (NT) is a new method that uses high-resolution digital images of nuclei to assess chromatin organisation both quantitatively and qualitatively. We aimed to evaluate NT as a marker of dysplasia in BO and compare with image cytometric DNA analysis (ICM). METHODS: In all, 120 patients with BO were studied. The non-dysplastic group (n=60) had specialised intestinal metaplasia only on two consecutive endoscopies after 51 months median follow-up (IQR=25-120 months). The dysplastic group (n=60) had high-grade dysplasia or carcinoma in situ. The two groups were then randomly assigned to a training set and a blinded test set in a 1:1 ratio. Image cytometric DNA analysis and NT was then carried out on Feulgen-stained nuclear monolayers. RESULTS: The best-fit model for NT gave a correct classification rate (CCR) for the training set of 83%. The test set was then analysed using the same textural features and yielded a CCR of 78%. Image cytometric DNA analysis alone yielded a CCR of 73%. The combination of ICM and NT yielded a CCR of 84%. CONCLUSION: Nucleotyping differentiates dysplastic and non-dysplastic BO, with a greater sensitivity than ICM. A combination score based on both techniques performed better than either test in isolation. These data demonstrate that NT/ICM on nuclear monolayers is a very promising single platform test of genomic instability, which may aid pathologists in the diagnosis of dysplasia and has potential as a biomarker in BO.

The prognostic value of DNA ploidy in a total population of uterine sarcomas.

BACKGROUND: The diagnosis of uterine sarcoma is associated with poor outcome for the patient and there is a need for reliable prognostic markers. Most previous studies on the prognostic value of DNA ploidy include few uterine sarcomas and report conflicting results. MATERIALS AND METHODS: We examined the prognostic value of DNA ploidy and its association with clinicopathological parameters and crude survival in a total population of 354 sarcoma. RESULTS: In univariate analyses, we observed significantly better crude survival for endometrial stromal sarcomas (ESS) and adenosarcoma (AS) patients with diploid as compared with nondiploid tumors, but not for patients with leiomyosarcomas (LMS). In Cox multivariate analyses, DNA ploidy was the only significant predictor of survival for patients with AS. In LMS, mitotic index (MI), tumor size, tumor extent and tumor margins, whereas for ESS, MI, tumor extent and tumor necrosis obtained independent significance of survival. DNA ploidy was a significant predictor of survival for LMS patients in Cox regression analyses when excluding MI. CONCLUSION: DNA ploidy might be useful as a prognostic marker in patients with LMS and AS.

Prognostic factors in ovarian carcinoma stage III patients. Can biomarkers improve the prediction of short- and long-term survivors?

The aim of the study was to determine if biomarker expression could help discriminate between short-term and long-term survivors in women with advanced ovarian cancer. Fifty-one patients with stage III ovarian cancer were selected for the study, which included 28 short-term survivors (death from ovarian cancer within 18 months) and 23 long-term survivors (alive for more than 5 years). There was no difference between the two groups with respect to FIGO substage, age, World Health Organization score, and first-line platinum therapy. Classic clinical pathologic parameters were examined together with p53, Bcl-2, Ki-67, PDGFRalpha, P-glycoprotein, BRCA1, and DNA ploidy. Immunohistochemistry was used for scoring biomarker expression and image cytometry for DNA ploidy. All patients had primary debulking surgery followed by first-line platinum therapy. On multivariate analysis, the presence of ascites, debulking surgery and repeat laparotomy, clear-cell histology, elevated CA125, and high Ki-67 score were all found to be of prognostic importance. The long-term survivors were characterized by primary optimal cytoreduction surgery (<1 cm residual disease), attempt at maximal tumor debulking by experienced gynecological oncologic surgeons, and the absence of ascites. Normal CA125 level before platinum therapy and negative Ki-67 expression also predicted a more favorable prognosis.

TP53 mutations in early-stage ovarian carcinoma, relation to long-term survival.

We conducted the present study to evaluate the frequency and prognostic importance on long-term survival of TP53 mutations and TP53 protein accumulation in a cohort of 178 patients with early-stage ovarian carcinomas. TP53 mutations scored as aberrant temporal temperature gradient gel electrophoresis pattern from all exons were observed in 39.9% of the tumours. Full screening of exons 5-8, followed by sequencing, was successful in 135 cases, and 48 mutations altering the protein were detected in 39 cases (28.9%). TP53 mutations were slightly less common in the Federation of Gynecologists and Obstetricians stage IA than in IB/IC (P=0.05). No significant correlations with histological type, grade of differentiation, DNA ploidy status or age at diagnosis were found. TP53 protein accumulation analysed by immunohistochemistry was found in 32.6% of all tumours, and was a poor predictor of TP53 mutations with 56.4% sensitivity, 77.1% specificity, 50% positive predictive value and 81.3% negative predictive value. Neither TP53 mutations nor TP53 protein accumulation influenced the prognosis significantly in this group of patients.

Large-scale genomic instability predicts long-term outcome for women with invasive stage I ovarian cancer.

BACKGROUND: The objective was to evaluate the value of DNA ploidy using high-resolution image cytometry in predicting long-term survival of patients with early ovarian cancer. PATIENTS AND METHODS: A retrospective analysis of 284 cases with FIGO stage I ovarian carcinoma treated during the period 1982-1989 was performed. Clinical follow-up information was available for all patients. RESULTS: Patients with diploid and tetraploid tumors had a 10-year relapse-free survival of 95% and 89%, respectively, compared with 70% and 29% for polyploid and aneuploid tumors, respectively. DNA ploidy analysis was the strongest predictor of survival in multivariate analysis (diploid/tetraploid versus polyploid/aneuploid; relative hazard 9.0) followed by histological grade, including clear cell tumors in the group of poorly differentiated tumors (grade 1-2 versus grade 3 or clear cell; relative hazard 2.7), and FIGO stage (Ib/Ic versus Ia; relative hazard 2.0). In a stratified Kaplan-Meier analysis, patients with grade 1-2, diploid or tetraploid tumors had a 10-year relapse-free survival of 95%, forming a low-risk group. Patients with grade 3 or clear cell, diploid or tetraploid tumors had 10-year relapse-free survival of 86%, forming an intermediate-risk group, while all patients with aneuploid/polyploid tumors formed a high-risk group, with 10-year relapse-free survival of 34%. CONCLUSIONS: This study points to the importance of including DNA ploidy analysis by image cytometry when selecting patients with early ovarian cancer for adjuvant treatment after surgery.

TP53 and p21WAF1/CIP1 behave differently in euploid versus aneuploid bladder tumours treated with radiotherapy.

The aim of this study was to examine any relation between DNA ploidy and previously detected TP53 (p53) or p21WAF1/CIP1 expression in 94 patients with muscle-invasive transitional cell carcinoma of the urinary bladder and to associate these factors with survival. DNA ploidy was determined by image cytometry. In a subgroup of patients, the mutational status of the TP53 gene was assessed by temporal temperature gradient electrophoresis (TTGE) or perpendicular denaturant gradient gel electrophoresis (DGGE) and subsequent sequencing. Significantly more aneuploid than euploid tumours showed TP53 accumulation (p = 0.003). Patients with aneuploid tumours lived longer than patients with euploid tumours (p = 0.003). In the euploid, but not in the aneuploid group, TP53 and p21WAF1/CIP1 were associated with cancer-specific survival (p = 0.002 and 0.02, respectively). Patients with > 50% TP53 expression had the longest survival time. Mutation analyses showed acceptable concordance with TP53 expression. We conclude that DNA aneuploidy may confer increased radiosensitivity in bladder cancer patients and that TP53 accumulation may confer increased radiosensitivity, but its effect is detectable only in euploid tumours.

Familial/bilateral and sporadic testicular germ cell tumors show frequent genetic changes at loci with suggestive linkage evidence.

Testicular germ cell tumor (TGCT) is the most common tumor type among adolescent and young adult males. Familial clustering and bilateral disease are suggestive of a genetic predisposition among a subgroup of these patients, but susceptibility genes for testicular cancer have not yet been identified. However, suggestive linkage between disease and genetic markers has been reported at loci on chromosome arms 3q, 5q, 12q, 18q, and Xq. We have analyzed primary familial/bilateral (n=20) and sporadic (n=27) TGCTs, including 28 seminomas and 19 nonseminomas, for allelic imbalance (AI) within the autosomal regions. DNA from all tumors were analyzed by fluorescent polymerase chain reaction of 22 polymorphic loci at 3q27-ter, 5q13-35.1, 12q21-ter, and 18q12--ter. All tumor genotypes were evaluated against their corresponding constitutional genotypes. The percentages of TGCTs with genetic changes at 3q, 5q, 12q, and 18q, were 79%, 36%, 53% and 43%, respectively. The frequencies at 3q and 12q in nonseminomas were significantly higher than in seminomas (P=.003 and P=.004). In order to evaluate changes at hemizygous Xq loci, five loci were analyzed by co-amplification with an autosomal reference marker known to reveal retained heterozygosity in the tumor DNA. Gain of Xq sequences was seen in more than 50% of the tumors. The degree of amplification varied among the loci in each of five tumors, and based on these breakpoints, a common region of overlapping gains was found at Xq28. No significant differences were found between the frequencies of genetic changes in familial/bilateral versus sporadic tumors, an observation speaking in disfavor of the existence of a single susceptibility gene for TGCT in any of the analyzed regions. Our data suggest that gain of genetic material at distal Xq and losses at 5q and 18q contribute to establishment of seminomas, whereas imbalances at 3q as well as gain at distal part of 12q are associated with further progression into nonseminomas.

Comparison of histological grading and large-scale genomic status (DNA ploidy) as prognostic tools in oral dysplasia.

Approximately one in ten oral white patches (leukoplakia) are histologically classified as dysplasia, with a well-documented potential for developing into oral squamous cell carcinoma (OSCC). Histological grading in oral dysplasia has limited prognostic value, whereas large-scale genomic status (DNA ploidy, nuclear DNA content) is an early marker of malignant transformation in several tissues. Biopsies from 196 patients with oral leukoplakia histologically typed as dysplasia were investigated. Inter-observer agreement among four experienced pathologists performing a simplified grading was assessed by Cohen's kappa values. For 150 of the 196 cases, it was also possible to assess large-scale genomic status and compare its prognostic impact with that of histological grading. Disease-free survival was estimated by life-table methods, with a mean follow-up time of 103 months (range 4-165 months). The primary considered end-point was the subsequent occurrence of OSCC. For grading of the total of 196 cases, kappa values ranged from 0.17 to 0.33 when three grading groups (mild, moderate, and severe dysplasia) were considered, and from 0.21 to 0.32 when two groups (low grade and high grade) were considered (p=0.41). For the 150 cases in which large-scale genomic status was also assessed, kappa values for the histological grading ranged from 0.21 to 0.33 for three grading groups and from 0.27 to 0.34 for two grading groups (p=0.47). In survival analysis, histological grading was without significant prognostic value for any of the four observers (p 0.14-0.44), in contrast to DNA ploidy (p=0.001). It is concluded that DNA ploidy in oral dysplasia has a practical prognostic value, unlike histological grading of the same lesions.

DNA content as a prognostic marker in patients with oral leukoplakia.

BACKGROUND: Oral leukoplakia may develop into squamous-cell carcinoma, which has a poor prognosis. Risk factors for oral carcinoma have been identified, but there are no reliable predictors of the outcome in individual patients with oral leukoplakia. METHODS: We identified 150 patients with oral leukoplakia that was classified as epithelial dysplasia and measured the nuclear DNA content (ploidy) of the lesions to determine whether DNA ploidy could be used to predict the clinical outcome. Biopsy specimens obtained at annual follow-up visits were graded histologically and classified with respect to DNA content in a blinded fashion. Disease-free survival was assessed in relation to DNA ploidy and the histologic grade. The mean duration of follow-up was 103 months (range, 4 to 165). RESULTS: Among 150 patients with verified epithelial dysplasia, a carcinoma developed in 36 (24 percent). Of the 150 patients, 105 (70 percent) had diploid (normal) lesions, 20 (13 percent) had tetraploid (intermediate) lesions, and 25 (17 percent) had aneuploid (abnormal) lesions at the time of the initial diagnosis. A carcinoma developed in 3 of the 105 patients with diploid lesions (3 percent), as compared with 21 of the 25 patients with aneuploid lesions (84 percent), yielding a negative predictive value of 97 percent with respect to the diploid lesions and a positive predictive value of 84 percent with respect to the aneuploid lesions. Carcinoma developed in 12 of 20 patients with tetraploid lesions (60 percent). The mean time from the initial assessment of the DNA content to the development of a carcinoma was 35 months (range, 4 to 57) in the group with aneuploid lesions and 49 months (range, 8 to 78) in the group with tetraploid lesions (P=0.02). The cumulative disease-free survival rate was 97 percent among the group with diploid lesions, 40 percent among the group with tetraploid lesions, and 16 percent among the group with aneuploid lesions (P<0.001). CONCLUSIONS: The DNA content in cells of oral leukoplakia can be used to predict the risk of oral carcinoma.

Prognostic classification of early ovarian cancer based on very low dimensionality adaptive texture feature vectors from cell nuclei from monolayers and histological sections.

In order to study the prognostic value of quantifying the chromatin structure of cell nuclei from patients with early ovarian cancer, low dimensionality adaptive fractal and Gray Level Cooccurrence Matrix texture feature vectors were extracted from nuclei images of monolayers and histological sections. Each light microscopy nucleus image was divided into a peripheral and a central part, representing 30% and 70% of the total area of the nucleus, respectively. Textural features were then extracted from the peripheral and central parts of the nuclei images.The adaptive feature extraction was based on Class Difference Matrices and Class Distance Matrices. These matrices were useful to illustrate the difference in chromatin texture between the good and bad prognosis classes of ovarian samples. Class Difference and Distance Matrices also clearly illustrated the difference in texture between the peripheral and central parts of cell nuclei. Both when working with nuclei images from monolayers and from histological sections it seems useful to extract separate features from the peripheral and central parts of the nuclei images.

[Telepathology at the Norwegian Radium Hospital]. / Telepatologi ved Det Norske Radiumhospital.

BACKGROUND: The article gives an overview of the telepathology activity at the Norwegian Radium Hospital from the service was launched in 1994 and up until today. We show the development during these years and discuss telepathology in general terms. We also discuss those aspects that determine how well a telepathology service functions. MATERIAL AND METHODS: 74 frozen section slides were diagnosed by two different telepathology systems. One of these systems was used for examining its appropriateness as a tool for second opinion in pathology. A new Internet-based system was developed that provided additional functionality. RESULTS: A telepathology system with a digital camera outperforms one with an analog camera with respect to diagnostic accuracy. INTERPRETATION: Image quality determines the precision of a telepathology service. Telepathology is a feasible tool for second opinion in pathology.