Disruption of G-quadruplex dynamicity by BRCA2 abrogation instigates phase separation and break-induced replication at telomeres

Dynamic interaction between BRCA2 and telomeric G-quadruplexes (G4) is crucial for maintaining telomere replication homeostasis. Cells lacking BRCA2 display telomeric damage with a subset of these cells bypassing senescence to initiate break-induced replication (BIR) for telomere synthesis. Here we show that the abnormal stabilization of telomeric G4 following BRCA2 depletion leads to telomeric repeat-containing RNA (TERRA)-R-loop accumulation, triggering liquid-liquid phase separation (LLPS) and the assembly of Alternative Lengthening of Telomeres (ALT)-associated promyelocytic leukemia (PML) bodies (APBs). Disruption of R-loops abolishes LLPS and impairs telomere synthesis. Artificial engineering of telomeric LLPS restores telomere synthesis, underscoring the critical role of LLPS in ALT. TERRA-R-loops also recruit Polycomb Repressive Complex 2 (PRC2), leading to tri-methylation of Lys27 on histone H3 (H3K27me3) at telomeres. Half of paraffin-embedded tissue sections from human breast cancers exhibit APBs and telomere length heterogeneity, suggesting that BRCA2 mutations can predispose individuals to ALT-type tumorigenesis. Overall, BRCA2 abrogation disrupts the dynamicity of telomeric G4, producing TERRA-R-loops, finally leading to the assembly of telomeric liquid condensates crucial for ALT. We propose that modulating the dynamicity of telomeric G4 and targeting TERRA-R-loops in telomeric LLPS maintenance may represent effective therapeutic strategies for treating ALT-like cancers with APBs, including those with BRCA2 disruptions.

Comparison of long-term oncologic outcomes of central lumpectomy and conventional breast-conserving surgery for invasive breast cancer: propensity score matching analysis

PURPOSE

Central lumpectomy (CL) is a breast-conserving surgical (BCS) technique that involves excision of the nipple-areolar complex with breast tumor in centrally located breast cancers. We aimed to investigate the long-term clinical outcomes of CL in comparison with conventional BCS (cBCS).

METHODS

Patient records who underwent BCS with clear resection margins for invasive breast cancer between 2004 and 2018 were retrospectively reviewed. Of the total 6,533 patients, 106 (1.6%) underwent CL. Median follow-up duration was 73.4 months. 1:3 propensity score matching (PSM) and inverse probability of treatment weighting (IPTW) were used to minimize selection bias.

RESULTS

The CL group showed a significantly higher ipsilateral breast tumor recurrence (IBTR) rate than the cBCS group (10-year IBTR rate: 5.8% vs. 3.1%, p = 0.004), even after adjusting for other variables (hazard ratio (HR), 2.65; 95% confidence interval (CI), 1.07-6.60, p = 0.048). However, there were no significant differences observed in regional recurrence, distant metastasis, or overall survival rates between the two groups. Both PSM and IPTW analyses showed significantly higher IBTR in the CL group (PSM HR, 3.27; 95% CI, 0.94-11.36; p = 0.048 and IPTW HR, 4.66; 95%CI, 1.85-11.77; p < 0.001). Lastly, when analyzing 2,213 patients whose tumors were located within 3 cm of the nipple, the CL group showed a significantly higher IBTR than the cBCS group before and after PSM.

CONCLUSION

CL was associated with a higher rate of IBTR compared to cBCS, while other survival outcomes were comparable. For centrally located tumors, CL may be considered for patients preferring breast preservation. However, higher risk for IBTR should be informed and careful surveillance may be necessary during the early post-operative follow-up periods.

Omission of Breast Surgery in Predicted Pathologic Complete Response after Neoadjuvant Systemic Therapy: A Multicenter, Single-Arm, Non-inferiority Trial

PURPOSE

Advances in chemotherapeutic and targeted agents have increased pathologic complete response (pCR) rates after neoadjuvant systemic therapy (NST). Vacuum-assisted biopsy (VAB) has been suggested to accurately evaluate pCR. This study aims to confirm the non-inferiority of the 5-year disease-free survival of patients who omitted breast surgery when predicted to have a pCR based on breast magnetic resonance imaging (MRI) and VAB after NST, compared with patients with a pCR who had undergone breast surgery in previous studies.

METHODS

The Omission of breast surgery for PredicTed pCR patients wIth MRI and vacuum-assisted bIopsy in breaST cancer after neoadjuvant systemic therapy (OPTIMIST) trial is a prospective, multicenter, single-arm, non-inferiority study enrolling in 17 tertiary care hospitals in the Republic of Korea. Eligible patients must have a clip marker placed in the tumor and meet the MRI criteria suggesting complete clinical response (post-NST MRI size ≤ 1 cm and lesion-to-background signal enhancement ratio ≤ 1.6) after NST. Patients will undergo VAB, and breast surgery will be omitted for those with no residual tumor. Axillary surgery can also be omitted if the patient was clinically node-negative before and after NST and met the stringent criteria of MRI size ≤ 0.5 cm. Survival and efficacy outcomes are evaluated over five years.

DISCUSSION

This study seeks to establish evidence for the safe omission of breast surgery in exceptional responders to NST while minimizing patient burden. The trial will address concerns about potential undertreatment due to false-negative results and recurrence as well as improved patient-reported quality of life issues from the omission of surgery. Successful completion of this trial may reshape clinical practice for certain breast cancer subtypes and lead to a safe and less invasive approach for selected patients.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT05505357. Registered on August 17, 2022. Clinical Research Information Service Identifier: KCT0007638. Registered on July 25, 2022.

Increased risk of contralateral breast cancer for BRCA1/2 wild-type, high-risk Korean breast cancer patients: a retrospective cohort study

BACKGROUND

This study aimed to investigate the contralateral breast cancer (CBC) recurrence rate in Korean breast cancer patients according to their BRCA1/2 germline mutation status, focusing particularly on the CBC recurrence risk in BRCA1/2 negative (BRCAx) patients.

METHODS

We conducted a retrospective study on 13,107 primary breast cancer patients. The patients were divided into high-risk and low-risk groups for hereditary breast cancer based on the Korean National Health Insurance Service's eligibility criteria for BRCA1/2 germline mutation testing. The high-risk group was further categorized into the BRCA mutation group, the BRCAx group, and the not tested group. We evaluated the overall survival and cumulative risk of developing CBC in these patients.

RESULTS

Among 4494 high-risk patients, 973 (21.7%) underwent genetic testing for BRCA1/2 germline mutation, revealing mutations in 158 patients (16.2%). We observed significant overall survival differences across all four groups, with the high-risk, not-tested group demonstrating notably worse overall survival (p < 0.001). However, when adjusted for other prognostic factors, there was no significant differences in hazard ratio of death between the four groups. The cumulative risk of CBC also varied among the groups. Patients with BRCA1/2 mutations showed a 7.3-fold increased risk of CBC compared to the low-risk group (95% CI 4.11-13.0, p < 0.001). Interestingly, BRCAx patients also demonstrated a significantly higher risk of CBC (HR 2.77, 95% CI 1.76-4.35, p < 0.001). The prognostic importance of the BRCAx for CBC recurrence persisted after adjusting for the age and subtype, but became insignificant when the family history of breast cancer was adjusted.

CONCLUSION

Breast cancer patients who are at high risk of hereditary breast cancer but with wild-type BRCA 1/2 genes (BRCAx) have increased risk of developing contralateral breast cancer when compared to the low-risk patients. More careful surveillance and follow-up can be offered to these patients especially when they have family history of breast cancer.

Development and External Validation of a Machine Learning Model to Predict Pathological Complete Response After Neoadjuvant Chemotherapy in Breast Cancer

PURPOSE

Several predictive models have been developed to predict the pathological complete response (pCR) after neoadjuvant chemotherapy (NAC); however, few are broadly applicable owing to radiologic complexity and institution-specific clinical variables, and none have been externally validated. This study aimed to develop and externally validate a machine learning model that predicts pCR after NAC in patients with breast cancer using routinely collected clinical and demographic variables.

METHODS

The electronic medical records of patients with advanced breast cancer who underwent NAC before surgical resection between January 2017 and December 2020 were reviewed. Patient data from Seoul National University Bundang Hospital were divided into training and internal validation cohorts. Five machine learning techniques, including gradient boosting machine (GBM), support vector machine, random forest, decision tree, and neural network, were used to build predictive models, and the area under the receiver operating characteristic curve (AUC) was compared to select the best model. Finally, the model was validated using an independent cohort from Seoul National University Hospital.

RESULTS

A total of 1,003 patients were included in the study: 287, 71, and 645 in the training, internal validation, and external validation cohorts, respectively. Overall, 36.3% of the patients achieved pCR. Among the five machine learning models, the GBM showed the highest AUC for pCR prediction (AUC, 0.903; 95% confidence interval [CI], 0.833-0.972). External validation confirmed an AUC of 0.833 (95% CI, 0.800-0.865).

CONCLUSION

Commonly available clinical and demographic variables were used to develop a machine learning model for predicting pCR following NAC. External validation of the model demonstrated good discrimination power, indicating that routinely collected variables were sufficient to build a good prediction model.

Abstract P3-04-11: Longitudinal Changes of Contralateral Breast Mammographic Artificial Intelligence Algorithms Score in Ductal Carcinoma In Situ patient with Tamoxifen

Background Mammographic Artificial intelligence (AI) algorithms (Lunit insight MMG) draws attention as a diagnostic support tool for breast cancer detection. Lunit insight MMG provides a location suspected of breast cancer with a heatmap and a score reflecting the probability of the presence of suspicious areas. We investigated whether the Lunit insight MMG score is relevant for predicting the response to adjuvant tamoxifen. Methods Patients diagnosed with DCIS and underwent treatment at Seoul National University Hospital in 2010 were retrospectively enrolled. Clinical characteristics, tamoxifen use, survival data, and mammography images were extracted from the electronic medical records, and Lunit insight MMG scores were calculated retrospectively. We classified two groups according to tamoxifen treatment and compared the score change of contralateral breast from baseline to 5 years after surgery for DCIS. Change categories of Lunit insight MMG score included maintaining high risk, maintaining low risk, increasing from low risk to high risk, and decreasing from high risk to low risk. Results Of 100 patients, 50 (50%) had undergone tamoxifen treatment (group 1) and 50 (50%) had not (group 2). The median age of the patients was 48.4 years for group 1 and 51.5 years for group 2 (p=0.172). The median follow-up duration was 8.7 years for the whole cohort. Using Lunit insight MMG score, more patients in group 1 decreased in contralateral breast cancer (CBC) risk compared with group 2 (6.0% vs. 2.0%; P=.008). No patients in group 1 had an increase in CBC risk while 9 patients increased in group 2 (0% vs. 18.0%; P =.008). There was no ipsilateral breast cancer recurrence for the whole cohort, and two patients experienced contralateral invasive breast cancer in group 2. In two patients with CBC, the Lunit insight MMG score increased five years after surgery, one year and three years before the CBC diagnosis. Conclusions Longitudinal Changes of Mammographic AI algorithms Score may be a predictive surrogate marker for response to tamoxifen therapy in hormone receptor-positive DCIS.

Citation Format: Changjin Lim, Eun Kyung Park, Hong-Kyu Kim, Eunhye Kang, Ji-Jung Jung, Hyunsu Yeoh, Jang-il Kim, Jung Whan Chun, Han-Byoel Lee, Hyeong-Gon Moon, Wonshik Han. Longitudinal Changes of Contralateral Breast Mammographic Artificial Intelligence Algorithms Score in Ductal Carcinoma In Situ patient with Tamoxifen [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P3-04-11.

Abstract P5-01-04: Contralateral Axillary Lymph Node Metastasis after Ipsilateral Breast Tumor Recurrence: Is it distant metastasis or locoregional progression?

Background: Contralateral axillary lymph node metastasis (CAM) in breast cancer is currently classified as a stage IV disease but its prognosis is still controversial. Purpose: To determine outcomes in overall survival (OS) and disease-free survival (DFS) in patients with and without locoregional tumor recurrence who present with contralateral axillary lymph node metastasis (CAM). Methods: Patients with pathologically confirmed invasive breast cancer with metachronous CAM who received treatment between 1988 and 2017 were retrospectively reviewed. Patients with other distant metastases at the time of CAM diagnosis were excluded. The outcome of CAM in cases of IBTR and regional recurrence (RR) were compared to CAM not accompanied by locoregional tumor recurrence. Results: Thirty-eight patients with metachronous CAM were included in the study. Metachronous CAM occurred 55 months (interquartile range, 17-77 months) after surgical treatment of the primary tumor and median follow-up was 95 months (interquartile range, 49-117 months) from the initial operation date and 40 months (interquartile range, 15-54 months) from the diagnosis of CAM. At the time of initial CAM diagnosis, 11 patients had IBTR, 12 patients had RR, and 15 patients had no locoregional recurrence. The estimated 5-year OS was 49.1% and 5-year DFS was 45.3%. Although statistically insignificant due to small sample size, when stratified by loco regional recurrence, the prognosis of CAM patients with IBTR appeared to be better than those without locoregional recurrence (5-year OS: 88.9% vs. 41.4%, HR 5.88, p = 0.09) whereas the prognosis of CAM patients with RR was worse than those without locoregional recurrence (5-year OS: 35.4% vs. 41.4%, HR 0.44, p = 0.20). Axillary lymph node dissection (ALND) improved median OS (83 vs. 36 months, p = 0.069) in all patients. When stratified, improvement in median OS was 13 vs 27 months (p = 0.094) in patients with RR, and 36 vs. 65 months (p = 0.061) in patients without locoregional recurrence. For patients accompanied by IBTR, ALND was performed in 8 out of 11 and only one patient died during the follow-up period. Conclusion: Our study indicates that the patients with CAM have superior survival outcome when compared to other stage IV patients, especially when CAM was accompanied by other loco regional recurrences. These data suggest that the CAM patients may benefit from active loco regional treatment.

Citation Format: Ji-Jung Jung, Hyeong-Gon Moon, Wonshik Han, Han-Byoel Lee, Hong-Kyu Kim, Jung Whan Chun, Eunhye Kang, Changjin Lim, Jang-il Kim, Hyunsu Yeoh. Contralateral Axillary Lymph Node Metastasis after Ipsilateral Breast Tumor Recurrence: Is it distant metastasis or locoregional progression? [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P5-01-04.

Abstract P6-02-14: Contralateral breast cancer risk in patients with or without BRCA mutation

Background: Patients who carry mutated BRCA1 or BRCA2 genes have a significantly increased risk of breast cancer and developing contralateral breast cancer (CBC). In this study, we aimed to investigate the acceptance rate of BRCA1/2 testing in Korean breast cancer patients and to determine the risk of CBC in Korean patients with BRCA 1/2 germline mutations. Methods: This study included 13,109 patients with first primary breast cancer who were treated at Seoul National University Hospital from January 2005 to December 2018. These patients were divided into high-risk for BRCA1/2 mutation group and low-risk group. High risk patients were defined as those who were eligible for BRCA testing per Korean National Health Insurance Service. The high-risk group was further classified into three groups; BRCA1/2 mutation carrier, BRCA 1/2 non carrier and BRCA/12 untested. Results: Among the 4,446 high-risk patients, 962 (21.7%) patients underwent BRCA1/2 testing. The testing rate varied among different indications (47.8% of patients with a family history, 23.3% of patients under 40 years of age, and 13.0% of patients with triple negative breast cancer). The risk of the CBC in BRCA mutation group was higher than other groups (p value &lt; 0.001). The 10-year cumulative risk of CBC was 11.0% BRCA1 mutation carrier and 7.4% for BRCA2 mutation carrier. In the BRCA1/2 non-carriers, the cumulative risk of CBC was 5.7%. Interestingly, the CBC risk for BRCA1/2 non-carriers significantly higher than BRCA1/2 untested group and the low-risk group (p &lt; 0.001). When compared to the BRCA1/2 untested group, the relative risk for CBC was 6.7-fold increase for the BRCA1/2 mutation carrier group (95% CI = 3.65-12.22, p &lt; 0.001), and 2.3-fold increase for the BRCA1/2 non-carriers group (95% CI = 1.44-3.83, p &lt; 0.001). The relative risk for CBC in high-risk group also depended on subtype of breast cancer and family history. Hormone receptor negative breast cancer patients had a 1.5-fold (95% CI = 1.02-2.31, p = 0.04) increased risk of CBC and patients with one or more 1st degree relative with breast cancer had 2.4-fold increased risk (95% CI = 1.55-3.67, p &lt; 0.001). Conclusion: About one out of five Korean breast cancer patients, who are eligible for the BRCA1/2 testing, undergo testing for BRCA1/2 germline mutations. We observed increased CBC risk not only for the BRCA1/2 mutation carriers but also for the BRCA1/2 non-carriers. At present, we are conducting multi-gene panel testing for the BRCA1/2 non-carriers to understand the mechanisms of the increased CBC risk.

Citation Format: Eunhye Kang, Ji-Jung Jung, Hyunsu Yeoh, Changjin Lim, Jang-il Kim, Jung Whan Chun, Hong-Kyu Kim, Han-Byoel Lee, Wonshik Han, Hyeong-Gon Moon. Contralateral breast cancer risk in patients with or without BRCA mutation [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P6-02-14.

Abstract P1-08-06: Development of an aritifical neural network model and comparison with nomogram for prediction of pathological complete response after neoadjuvant chemotherapy in breast cancer

Purpose: Identifying patients who may benefit from neoadjuvant chemotherapy will facilitate personalized treatment regarding chemotherapy and surgery. This study compares the predictive performance of an artificial neural network algorithm with nomogram to predict pathological complete response (pCR) after neoadjuvant chemotherapy (NAC) in patients with advanced breast cancer.. Methods: Medical records of 359 patients with advanced breast cancer who received NAC prior to surgical resection between January 2017 and December 2019 were retrospectively reviewed. Random over sampling method was used to overcome data imbalance and random sampling method to divide patients into training and test sets at a split ratio of 7:3. Univariate and multivariate regression analyses were used to develop a nomogram and a machine learning model based on artificial neural network. Performance of the two models were evaluated using the validation sets in terms of area under the receiver operating characteristic curve (AUC).. Results: Multivariate logistic regression analysis showed that high level of estrogen receptor (ER) (OR 0.84, p &lt; 0.001), positive human epidermal growth factor receptor 2 (HER2) status (OR 1.25, p &lt; 0.001), complete response on magnetic resonance imaging (MRI) (OR 1.62, p &lt; 0.001), abnormal CEA level after NAC (OR 0.86, p = 0.051), and abnormal CA15-3 level after NAC (OR 0.87, p = 0.074) were independent predictors of pCR. A nomogram and a neural network model to predict pCR were developed using the five predictors. Validation test showed AUCs of 0.789 [95 % confidence interval (CI), 0.707-0.871] for the nomogram and 0.876 [95 % CI, 0.808-0.943] for the neural network model.. Conclusion: We developed a nomogram and an artificial neural network (ANN)-based machine learning model to predict pCR after NAC. Both models showed excellent performance, but the ANN model performed better in terms of accuracy and discrimination. Machine-learning algorithms hold promise in medical application and provide better prediction than nomogram.

Citation Format: Hee-Chul Shin, Ji-Jung Jung, Eun-Kyu Kim, Eunyoung Kang. Development of an aritifical neural network model and comparison with nomogram for prediction of pathological complete response after neoadjuvant chemotherapy in breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P1-08-06.

Brain Structural Alterations, Diabetes Biomarkers, and Cognitive Performance in Older Adults With Dysglycemia

Despite the high risk of dementia in older adults with type 2 diabetes, the neuroanatomical correlates of cognitive dysfunction that are particularly affected by diabetes are not well characterized. This study is aimed to examine the structural brain alterations in dysglycemic older adults. Using voxel-based morphometric and tract-based spatial statistics, we examined changes in gray matter volume, white matter volume, and microstructural integrity in older adults with prediabetes and diabetes. We also assessed the correlation of these structural changes with diabetes biomarkers and cognitive performance. A total of 74 non-demented older adults (normal, n = 14; prediabetes, n = 37; and diabetes, n = 23) participated in this study and underwent structural and diffusion magnetic resonance imaging (MRI) scans and neuropsychological tests. Subjects with diabetes showed reduced volume of cerebellar gray matter and frontal white matter and diffuse white matter dysintegrity, while those with prediabetes only showed reduced volume of insular gray matter. Atrophic changes in the cerebellum and frontal lobe and frontal white matter dysintegrity were correlated with chronic hyperglycemia and insulin resistance and worse performance in verbal memory recognition and executive function tests. Our findings suggest that chronic hyperglycemia and insulin resistance may alter brain structures forming the fronto-cerebellar network, which may cause cognitive dysfunction in older adults.

External validation and modification of nomogram for predicting positive resection margins before breast conserving surgery

PURPOSE

A positive resection margin after breast conserving surgery (BCS) is the most important risk factor for tumor recurrence. In 2012, Seoul National University Hospital (SNUH) breast surgery team developed a nomogram for predicting positive resection margins before BCS to provide individual surgical plans that could reduce local recurrence without increasing re-excision rates. The purpose of this study was to validate this nomogram using an external cohort and to test if addition of surgeon-related factor could improve its use as a predictive model.

METHODS

A total of 419 patients with breast cancer who underwent BCS from January to December 2018 were retrospectively reviewed. Using the SNUH BCS nomogram, risk score for positive resection margins was calculated for 343 patients. The predictive accuracy of the nomogram was assessed, and multivariable logistic regression analyses were performed to evaluate the nomogram's predictive variables.

RESULTS

The positive resection margin rate of the current external validation cohort was 13.5% (46 out of 343), compared to 14.6% (151 out of 1034) of the original study. The discrimination power of the SNUH BCS nomogram as measure by area under the receiver operating characteristics curve (AUC) was 0.656 [95% confidence interval (CI) 0.576-0.735]. This result is lower than expected value of 0.823 [95% CI 0.785-0.862], the AUC of the original study. Multivariable logistic regression analysis showed that, among the five nomogram variables, presence of tumor size discrepancy greater than 0.5 cm between MRI and ultrasonography (OR 2.445, p = 0.019) and presence of ductal carcinoma in situ on needle biopsy (OR 2.066, p = 0.048) were significantly associated with positive resection margins. Finally, the nomogram score was re-calculated by adding each surgeon's resection margin positive rate as odds ratio and the AUC was increased to 0.733.

CONCLUSIONS

Validation of the SNUH BCS nomogram was not successful in the current study as much as its original publication. However, we could improve its predictive power by including surgeon-related factor. Before applying a published nomogram as a preoperative predictive model, we suggest each institution to validate the model and adjust it with surgeon-related factor. Addition of new factors to currently available nomograms holds promise for improving its applicability for breast cancer patients at the actual clinical level.

Angiopoietin-1 guides directional angiogenesis through integrin αvβ5 signaling for recovery of ischemic retinopathy

Retinopathy of prematurity (ROP) and proliferative diabetic retinopathy (PDR) are ischemic retinal diseases caused by insufficient vascular network formation and vascular regression in addition to aberrant angiogenesis. We examined the role of angiopoietin-1 (Ang1) in retinal vascular network formation during postnatal development using Ang1 gain- and loss-of-function mouse models, and tested the effects of intraocular administration of Ang1 in an oxygen-induced retinopathy (OIR) mouse model that mimics cardinal features of ROP and PDR. We observed that Ang1 plays a substantial role in the formation of the retinal vascular network during postnatal development and that Ang1 supplementation can rescue vascular retinopathies by simultaneously promoting healthy vascular network formation and inhibiting subsequent abnormal angiogenesis, vascular leakage, and neuronal dysfunction in the retinas of the OIR model. We attribute these Ang1-induced effects to a dual signaling pathway-Tie2 signaling in the vascular region and integrin αvβ5 signaling in the astrocytes. The activation of integrin αvβ5 signaling promoted fibronectin accumulation and radial distribution along the sprouting endothelial cells, which consequently stimulated guided angiogenesis in the retina. These findings shed light on the role of Ang1 in the recovery of ischemic retinopathies such as ROP, PDR, and retinal vascular occlusive disease.

Antioxidant effect of melatonin in human retinal neuron cultures

This study investigates whether the neurohormone melatonin can prevent the retinal neuronal injury caused by reactive oxygen species (ROS) in cultured human retinal neuronal cells. Cultures of human retinal neuronal cells established from a variety of donors were grown to 14 days and then subjected to experimental hypoxanthine/xanthine oxidase (HX/XO)-induced injury. Intracellular production of ROS by administration of HX/XO was confirmed by flow cytometry; the ROS resulted in both apoptotic and necrotic pattern of cell death in the retinal neuron cultures. The efficacy of melatonin against ROS injury was quantitated by MTT assay, enzyme immunoassay, and immunocytochemistry for neurofilament protein. The antioxidative effect of melatonin was compared with that of alpha-tocopherol. Retinal neuronal injury significantly reduced in a dose-response manner by a treatment of 1.0-8.0 mM alpha-tocopherol. Melatonin, in concentrations of more than 2.0 mM, also significantly reduced the injury. About 70% of cells are rescued by pretreatment with 1.0 mM alpha-tocopherol and 8.0 mM melatonin in the MTT assay. Our observations suggest that melatonin can rescue retinal neurons from ROS injury in human retinal cell cultures.

Mucocele-like tumor of the breast associated with ductal carcinoma in situ and mucinous carcinoma : a case report

Mucocele-like tumor (MLT) of the breast is a rare neoplasm. Although this lesion was considered benign when first described, the concept of a pathologic continuum with mucinous carcinoma was evident in subsequent reports. Only a few cases of MLT have been reported in Korea. We describe a case of MLT associated with ductal carcinoma in situ and mucinous carcinoma in a 34-yr-old female. Histological examination showed multiple mucus-filled cysts of varying size. Extravasated mucin was present in the surrounding stroma. The lining of the cysts in most areas were of flat or cuboidal epithelium and devoid of cellular atypia. The lining epithelium showed proliferative change ranging from atypical ductal hyperplasia to ductal carcinoma in situ, micropapillary type. A microscopic focus of mucinous carcinoma within MLT was also noted. None of the lesions exhibited epithelial reactivity for p53 protein. The patient is alive and well without evidence of disease 54 months after initial treatment. This case supports the concept that MLT encompasses a spectrum of pathologic lesions including benign tumor, atypical ductal hyperplasia, ductal carcinoma in situ, and mucinous carcinoma.

Expression of vascular endothelial growth factor in renal cell carcinoma and the relation to angiogenesis and p53 protein expression

BACKGROUND AND OBJECTIVES

Vascular endothelial growth factor (VEGF) seems to play an important role in tumor angiogenesis. The tumor-suppressor gene p53 has been thought to regulate VEGF expression. We investigated the effect of VEGF expression on renal cell carcinoma (RCC) and the correlation between the expression of VEGF and tumor angiogenesis and p53 protein expression.

METHODS

Sixty-two RCCs were examined by immunohistochemical studies with anti-VEGF, anti-p53, and anti-CD34 antibodies.

RESULTS

Forty tumors (80.6%) were classified as VEGF positive, and 28 tumors (45.2%) were positive for p53 protein. The microvessel density was 75.3 +/- 33.5. A significant correlation was found between VEGF expression and both the nuclear grade (P < 0.05) and the TNM stage (P < 0.05). The tumors with VEGF expression had a significantly higher microvessel density than those without VEGF expression (P < 0.01). There was no statistically significant correlation between p53 protein and VEGF expression. No statistically significant differences in survival were found to be associated with microvessel density, VEGF expression or p53 protein expression. By using multivariate survival analyses, nuclear grade (P < 0.05) and TNM stage (P < 0.05) were the only independent prognostic factors.

CONCLUSIONS

Our data do not show a direct regulation of VEGF expression by p53. We suggest that VEGF expression plays a role in the promotion of angiogenesis in RCC.

Correlation between angiogenesis, apoptosis and cell proliferation in invasive ductal carcinoma of the breast and their relation to tumor behavior

OBJECTIVE

To investigate the relationship between angiogenesis, apoptosis and cell proliferation in invasive ductal carcinoma of the breast and their relation to tumor behavior.

STUDY DESIGN

Microvessels were immunohistochemically labeled with antibody to CD34 in sections from 82 cases of invasive ductal carcinoma. Computerized image analysis was used to evaluate microvessel density (MVD). The authors measured the apoptotic index (AI) using the terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labeling technique and proliferating cell nuclear antigen labeling index (PCNA LI) by PCNA immunohistochemistry on serial sections.

RESULTS

Statistical analysis revealed a significant inverse correlation between MVD and AI (r = -.313, P = .004) and failed to find a significant correlation between MVD and PCNA LI. There was a significant positive correlation between AI and PCNA LI (r = .393, P = .000). Significant differences in AI between high MVD (> or = 59.9%) and low MVD (< 59.9%) were seen (P < .001), with no appreciable differences in PCNA LI between the two groups. Histologic grade and stage were the only independent prognostic factors in both disease-free and overall survival.

CONCLUSION

Angiogenesis in breast cancer may be related to the ability of tumor cells to survive rather than to their proliferative activity. Apoptosis is related to cell proliferation in breast cancer.

Quantification of angiogenesis by a computerized image analysis system in renal cell carcinoma

OBJECTIVE

To ascertain whether tumor angiogenesis quantitated by a computerized image analysis system correlates with clinical outcome in renal cell carcinoma.

STUDY DESIGN

Microvessels were immunohistochemically labeled with antibodies to CD34 in sections from 62 cases of renal cell carcinoma. Computerized image analysis was used to evaluate the mean microvessel count (MMC) and mean percentage microvessel area (MPMA).

RESULTS

MMC ranged from 19.3 to 315.0, while MPMA was 0.6-17.9%. There was a highly significant correlation between MMC and MPMA (r = .867, P < .01). Although MMC and MPMA decreased with increasing nuclear grade and TNM stage, this difference failed to achieve statistical significance. No statistically significant differences in survival were found for MMC or MPMA.

CONCLUSION

Our results indicate that computerized image analysis can evaluate accurately tumor angiogenesis, but tumor angiogenesis in renal cell carcinoma does not provide significant prognostic information in renal cell carcinoma.

Value of morphometric nuclear image analysis using the Feulgen reaction in renal cell carcinoma

OBJECTIVE

To evaluate retrospectively the ability of morphometric nuclear image analysis to predict survival in patients with renal cell carcinoma.

STUDY DESIGN

The subjects were 40 patients with previously untreated renal cell carcinoma. Pathologic stage was determined using Robson's stage system. Nuclear grade was assigned according to the criteria of Fuhrman et al. We used the Feulgen staining technique, which has been widely used for the histochemical assessment of nuclear DNA content. A minimum of 300 nuclei were analyzed from each subject. Five variables in morphometric nuclear image analysis were measured: nuclear area, nuclear perimeter, nuclear ellipticity, nuclear regularity and DNA content. Cox's proportional hazard model was applied to identify prognostic usefulness with respect to survival time.

RESULTS

All nuclear morphometric variables but nuclear regularity correlated with tumor grade. According to univariate survival analyses, Robson stage and nuclear ellipticity revealed a prognosis on survival with statistical significance. After adjustments for age and sex, nuclear ellipticity remained the only significant prognostic factor related to survival (P < .01). The survival rates were relatively high for patients with nuclear ellipticity > 773 as compared to those with nuclear ellipticity < 773 (P < .05).

CONCLUSION

These findings indicate that morphometric nuclear image analysis using the Feulgen reaction is a reliable and efficient technique and that nuclear ellipticity is the most discriminating morphometric variable for predicting the prognosis of renal cell carcinoma patients.

[Role of allogeneic transplantation of bone marrow in juvenile chronic myelomonocytic leukemia]

Two boys with clinical and haematological evidence of juvenile chronic myelomonocytic leukaemia had no chromosomal anomaly. In addition, one presented with an unbalanced Epstein-Barr virus serology, and the other with xantholeukaemia. Allogenic bone marrow transplantation was performed in the first boy after an 18-month period during which treatment with 6-mercaptopurine, intensive chemotherapy and splenectomy had failed. Conditioning included cyclophosphamide, high-dose cytarabine and whole-body irradiation. There was no complication, and 16 months after transplantation the patient was in complete remission. The second boy received a bone marrow transplant on the 6th month of the disease, after failure of 6-mercaptopurine. Conditioning included etoposide, busulfan and cyclophosphamide. On the 35th post-transplantation day the child had severe pancytopenia and his spleen remained enlarged. A second transplantation was performed after treatment with melphalan and whole-body irradiation. Twelve months later, the patient was in complete remission. The indications and modalities of allogenic bone marrow transplantation in juvenile chronic myelomonocytic leukaemia and the value of pre-transplantation splenectomy are discussed.