Validation of the Singapore nomogram for outcome prediction in breast phyllodes tumours in a large patient cohort

Detailed DNA methylation characterisation of phyllodes tumours identifies a signature of malignancy and distinguishes phyllodes from metaplastic breast carcinoma

Phyllodes tumours (PTs) are rare fibroepithelial lesions of the breast that are classified as benign, borderline, or malignant. As little is known about the molecular underpinnings of PTs, current diagnosis relies on histological examination. However, accurate classification is often difficult, particularly for distinguishing borderline from malignant PTs. Furthermore, PTs can be misdiagnosed as other tumour types with shared histological features, such as fibroadenoma and metaplastic breast cancers. As DNA methylation is a recognised hallmark of many cancers, we hypothesised that DNA methylation could provide novel biomarkers for diagnosis and tumour stratification in PTs, whilst also allowing insight into the molecular aetiology of this otherwise understudied tumour. We generated whole-genome methylation data using the Illumina EPIC microarray in a novel PT cohort (n = 33) and curated methylation microarray data from published datasets including PTs and other potentially histopathologically similar tumours (total n = 817 samples). Analyses revealed that PTs have a unique methylome compared to normal breast tissue and to potentially histopathologically similar tumours (metaplastic breast cancer, fibroadenoma and sarcomas), with PT-specific methylation changes enriched in gene sets involved in KRAS signalling and epithelial-mesenchymal transition. Next, we identified 53 differentially methylated regions (DMRs) (false discovery rate < 0.05) that specifically delineated malignant from non-malignant PTs. The top DMR in both discovery and validation cohorts was hypermethylation at the HSD17B8 CpG island promoter. Matched PT single-cell expression data showed that HSD17B8 had minimal expression in fibroblast (putative tumour) cells. Finally, we created a methylation classifier to distinguish PTs from metaplastic breast cancer samples, where we revealed a likely misdiagnosis for two TCGA metaplastic breast cancer samples. In conclusion, DNA methylation alterations are associated with PT histopathology and hold the potential to improve our understanding of PT molecular aetiology, diagnostics, and risk stratification. © 2024 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Multidisciplinary Management of Phyllodes Tumours and Breast Sarcoma: A Cross-sectional Survey of Clinical Practice across the UK and Ireland

AIMS

Phyllodes tumours and breast sarcomas are uncommon tumours and their rarity poses significant challenges in diagnosis and management. This cross-sectional study was conducted to evaluate the multidisciplinary clinical practice for these tumours across the UK and Ireland, with the aim of identifying gaps in knowledge and providing direction for establishing national guidelines.

MATERIALS AND METHODS

An international survey was adapted and circulated to breast and/or sarcoma surgeons and oncologists in the UK and Ireland through national organisations. Multidisciplinary team (MDT) responses were analysed anonymously.

RESULTS

Twenty-eight MDTs participated in this study, predominately from high-volume units (85.5%). Although only 43% of the surveyed units were part of a trust that holds a sarcoma MDT, 68% of units managed malignant phyllodes and angiosarcoma, whereas 64.5% managed soft-tissue sarcoma of the breast. Across all subtypes, axillary surgery was recommended by 14-21% of the MDTs and the most recommended resection margins for breast surgery were 'no tumour on ink' in benign phyllodes (39%) and 10 mm in the remaining subtypes (25-29%). Immediate breast reconstruction was supported by 11-18% of MDTs for breast sarcoma subtypes, whereas 36% and 32% advocated this approach in benign and borderline phyllodes tumours, respectively. Adjuvant radiotherapy and chemotherapy were recommended by up to 29% and 11% of the MDTs, respectively.

CONCLUSION

The results of this study demonstrate a wide variation in clinical practice across the surveyed MDTs. As only 28 MDTs participated in our study, with under-representation from low-volume units, our results might be an underestimation of the variability in practice across the UK and Ireland. This multi-institutional study sheds light on controversial aspects in the management of phyllodes tumours and breast sarcoma, identifies the need for national guidelines to inform best practice, and calls for the centralisation of the management of breast sarcoma within specialist centres.

Phyllodes tumour evidence gaps mapped from the 5th edition of the WHO classification of tumours of the breast

AIMS

Breast phyllodes tumours (PTs) are a rare subset of fibroepithelial neoplasms categorised into benign, borderline, and malignant grades according to the World Health Organization (WHO) Classification of Tumours (WCTs). In this report, we developed an evidence gap map (EGM) based on the literature cited in the PT chapter of the 5th edition of the breast WCT in order to identify knowledge and research gaps in PT.

METHODS

A framework was first established where the dimensions of the EGM were defined as categories of tumour descriptors, tumour types, and evidence levels. Citations were collected into a Microsoft Excel form and imported into EPPI-reviewer to produce the EGM.

RESULTS

The EGM showed that the "Histopathology" and "Pathogenesis" sections contained the most citations, the majority being of low-level evidence. The highest number of citations considered of moderate-level evidence were found in the "Histopathology" section. There was no high-level evidence cited in this chapter. The "Localisation", "Aetiology", and "Staging" sections had the fewest citations.

CONCLUSION

This EGM provides a visual representation of the cited literature in the PT chapter of the breast WCT, revealing the lack of high-level evidence citations. There is an uneven distribution of references, probably due to citation practices. Pockets of low-level evidence are highlighted, possibly related to referencing habits, lack of relevant research, or the belief that the information presented is standard accepted fact, without the need for specific citations. Future work needs to bridge evidence gaps and broaden citations beyond those in the latest WCT.

Refining the classification of breast phyllodes tumours

Phyllodes tumours of the breast are uncommon fibroepithelial neoplasms that pose recurrent classification challenges, in large part due to the multiple histological parameters of stromal hypercellularity and atypia, stromal mitotic count, stromal overgrowth and tumour borders, that are used for grading. While the World Health Organization (WHO) Classification of Breast Tumours provides recommendations on diagnostic features, defining criteria are not always applied in routine practice. Lack of concordance among pathologists in typing and grading further underscores the classification difficulties, especially in the borderline category. Although there has been significant molecular information on phyllodes tumours in recent years which has been diagnostically helpful, it has not been translated into daily clinical practice. In order to refine the classification of phyllodes tumours into one that is simple yet comprehensive, reproducible and prognostically precise, a multipronged approach is needed that leverages on global contributions of the International Fibroepithelial Consortium, support by the International Collaboration on Cancer Classification and Research (IC³ R) in amalgamating evidence translation, and guidance from the International Collaboration on Cancer Reporting (ICCR) for standardised reporting. It is hoped that the evidence generated can be used towards refining the classification of phyllodes tumours for the future.

Margin Status and Local Recurrence in Phyllodes Tumours of the Breast: A Canadian Series

BACKGROUND

Phyllodes tumours of the breast are rare fibroepithelial neoplasms with a propensity for recurrence. While surgical excision remains the standard of care, the optimal margin width is an area of active investigation. Recent studies have questioned the necessity for wide, local excision.

METHODS

We conducted a retrospective, cohort study of patients with phyllodes tumours treated at our institution between 2003 and 2021. Demographic, histopathological, and recurrence data were captured; malignant phyllodes were excluded. Cox proportional hazard models were used to identify covariates associated with local recurrence.

RESULTS

Of 187 patients with phyllodes tumours, 82.9% (n = 155) were classified as benign while 17.1% (n = 32) were borderline. Initial surgical margins were positive in 26.2% (n = 49), < 2 mm in 50.8% (n = 95), and ≥ 2 mm in 23% (n = 43) patients. Among patients with positive margins, 61.2% (n = 30) underwent margin revision. At a median follow-up of 2.9 years, the recurrence rate was 3.7%. On univariate analysis, only a positive margin at the time of initial surgery and not margin width was significantly associated with a higher rate of disease recurrence (hazard ratio [HR] 9.52, 95% confidence interval [CI] 1.85-49.2), as was a size greater than 4 cm on preoperative imaging (HR 10.78, 95% CI 0.97-120.1). Revision of an initially positive margin was not significantly associated with decreased local recurrence (p = 1).

CONCLUSIONS

In this large cohort of benign and borderline phyllodes tumours, positive resection margins and not margin width at the initial surgery were associated with a increased recurrence. Individualization of decisions regarding margin reexcision is important.

Management of phyllodes tumor: A systematic review and meta-analysis of real-world evidence

BACKGROUND

Phyllodes tumor is rare but has a high recurrence rate. Treatment modalities and clinicopathological prognostic factors for recurrence remain unclear. The synthesis of real-world data can enable the integration of sufficient evidence on optimal treatment for this population.

METHODS

We searched PubMed, Embase, and Cochrane Library databases for studies focusing on the management of phyllodes tumor including the surgical margin, different clinicopathological prognostic factors, and postoperative adjuvant radiotherapy versus no radiotherapy.

RESULTS

Fifty-two studies were retrieved. The pooled estimated recurrence rates of benign, borderline, and malignant tumors were 7.1%, 16.7%, and 25.1%, respectively. Surgical margins of 1 mm (odds ratio [OR]: 0.4, 95% confidence interval [CI]: 0.27-0.61) and 1 cm (OR: 0.45, 95% CI: 0.15-0.85) resulted in significantly higher recurrence rates. Postoperative adjuvant radiotherapy significantly reduced the recurrence rate of malignant tumors relative to no radiotherapy (P = 0.034) but did not significantly reduce the recurrence rates of overall and borderline tumors. Regarding clinicopathological features, moderate or severe stromal atypia and hypercellularity, stromal overgrowth, mitotic number of 5, tumor necrosis, tumor border, and margin status were determined as independent prognostic factors for recurrence, except a tumor size of 5 cm.

CONCLUSION

The ideal surgical margin for phyllodes tumor incision should be at least 1 cm in width. Adjuvant radiotherapy reduced the recurrence of malignant tumor. By identifying patients with poor clinicopathological risk factors, surgeons may reduce the recurrence rate of phyllodes tumor.

Prognostic Significance of Three-Tiered World Health Organization Classification of Phyllodes Tumor and Correlation to Singapore General Hospital Nomogram

OBJECTIVES

Phyllodes tumors (PTs) are categorized by the World Health Organization (WHO) as benign, borderline, and malignant. Singapore General Hospital (SGH) nomogram is a recurrence risk assessment tool for PT, which uses cytologic atypia, mitosis, stromal overgrowth, and the surgical margin status. We studied the prognostic significance of WHO classification and its correlation to the SGH nomogram.

METHODS

We identified 270 consecutive cases of PT (195 benign, 49 borderline, 26 malignant). Follow-up was available on 246 cases (mean follow-up of 51 months).

RESULTS

The recurrence rates were 2% (4 of 176) for benign, 4% (2 of 46) for borderline, and 25% (6 of 24) for malignant (log-rank test P < .0001 for recurrence-free survival). Only five patients with malignant PT experienced distant recurrence. Stromal overgrowth was an independent predictor of recurrence-free survival on multivariable analysis. The mean nomogram scores for benign, borderline, and malignant PT were 20, 20.3, and 32, respectively. The higher than expected score for benign PT was due to positive margins in 39% of cases.

CONCLUSIONS

The WHO three-tiered classification of PT is prognostic. Despite positive margin status, most benign PTs do not recur. Other features of the nomogram help in determining recurrence but are also used for WHO classification.

Surgical management in phyllodes tumors of the breast: a systematic review and meta-analysis

BACKGROUND

Information is still controversial in the studies regarding the current optimal surgical management of phyllodes tumors (PTs) of the breast. Local recurrence (LR) may occur with an upgraded in the pathological grade, influencing the prognosis of patients with PT. This systematic review and meta-analysis aimed to investigate the association of LR risk with margin status and margin width which could have significant implications on the surgical management of PT.

METHODS

Independent and comprehensive searches were performed by two authors through five databases including PubMed, Medline, Embase, ScienceDirect and Cochrane Library from January 1990 to October 2021. Studies investigating the association between margin width, margin status and LR rates were considered for inclusion. Study quality was evaluated using the Newcastle-Ottawa Scale (NOS). Meta-analysis was performed using RevMan5.3 software, and statistical heterogeneity was assessed using the Chi-square test and quantified using the I2 statistic. Visual inspection of funnel plots was used to judge publication bias.

RESULTS

A total of 34 articles were included in this article, all of which with NOS scores above 5. Regardless of the PT grade, positive margin significantly increased the risk of LR [odds ratio (OR) 3.64, 95% confidence interval (CI): 2.60-5.12]. No significant difference was found in the risk of LR between the margins <1 and ≥1 cm (OR 1.39, 95% CI: 0.67-2.92). For benign and borderline PTs, there were no significant differences of the LR risk between breast-conserving surgery (BCS) and mastectomy (benign OR 0.68, 95% CI: 0.12-3.78; borderline OR 1.14, 95% CI: 0.29-4.51). While the LR risk was significantly increased by BCS for malignant PT (OR 2.77, 95% CI: 1.33-5.74).

DISCUSSION

Different surgical management strategies should be considered for different PT grades. BCS was a feasible option and margins <1 cm was not significantly associated with LR risk for all grade of PT. After BCS, benign PT with positive margin could adopt the "wait and watch" strategy with regular follow-up, while borderline and malignant PTs were expected to underwent re-excision to ensure negative margins. More studies are still needed to clarify and update the existing conclusions and improve the prognosis of PT patients.

Diagnosis and management of phyllodes tumours for the surgeon: An algorithm

A Phyllodes Tumour (PT) is an uncommon fibroepithelial lesion, with three histological grades - benign, borderline and malignant. PTs cause significant challenges in diagnosis, management and prognostication. Recent publications have clarified the definitions and prognostication of PTs. Contemporary data currently challenge international guidelines on PT management. We performed an in-depth literature review to develop a best-practice management algorithm for PTs. Diagnostic recommendations are that neither current imaging techniques, nor fine-needle biopsies, can reliably diagnose a PT. Core needle biopsy is the optimal diagnostic technique. Indeterminate or suspicious lesions are recommended to undergo an excisional biopsy due to the inherently heterogeneous nature of PTs. Management guidelines are that benign PTs should be completely excised, although an involved margin is acceptable in select situations. Borderline PTs should have a clear margin on excision due to their higher risk of recurrence, as well as the potential for a recurrence to progress to a malignant PT. In malignant PTs, a margin of 3 mm is acceptable as there is no reduction in recurrence risk if margins are >3 mm. Routine axillary surgery is not indicated in PTs, with axillary surgery only indicated in a histologically-confirmed positive axilla. Adjuvant treatment recommendations are that borderline and malignant PTs should be discussed at MDT, with radiotherapy considered in both. Chemotherapy should be discussed in malignant PT patients. In summary, we have developed an up-to-date simple algorithm to guide the surgeon's management of patients diagnosed with PTs and reduce excessive surgery.

Phyllodes Tumors: A Scoping Review of the Literature

PURPOSE

Phyllodes tumors are rare tumors of the breast, with most literature being retrospective with limited guidelines on the management of these patients. Scoping review was performed to highlight themes and gaps in the available literature.

METHODS

A scoping review of the literature was performed as per PRISMA-ScR guidelines with titles, abstracts, and full texts reviewed in duplicate. Data were abstracted and summarized in categories of diagnostics, surgical management, adjuvant therapies, treatment of recurrence, and surveillance. Quality assessment was performed for each paper.

RESULTS

The search identified 4498 references, 434 full-text papers were reviewed, and 183 papers were included. Ultrasound, magnetic resonance imaging, and core needle biopsy are valuable preoperative diagnostics tools. Pathology reporting should include stromal overgrowth, stromal cellularity, nuclear atypia, mitotic rate, borders, and presence of heterologous elements. Ki67 may have a role in grading and prognosticating. Breast conservation is safe in all grades of phyllodes but may be associated with increased local recurrence in malignant phyllodes. Surgical margins should depend on grade. Axillary node positivity rate is very low, even with clinically enlarged lymph nodes. Adjuvant radiation is a useful tool to decrease local recurrence in malignant phyllodes tumors, tumors > 5 cm, age < 45 years, close margins, and breast conservation. There is no evidence supporting adjuvant chemotherapy. Recurrence can be managed with repeat wide excision; however, mastectomy is associated with lower re-recurrence. Surveillance protocols are variable in the literature.

CONCLUSIONS

There is heterogeneity in the literature on phyllodes tumors. Consensus guidelines based on the literature will help provide evidence-based care.

CD117/c-KIT Expression in Phyllodes Tumor of the Breast and Its Correlation With Morphology and Clinical Outcome

Introduction

Breast phyllodes tumor’s (PT) clinical behavior is difficult to predict on histology. There is limited amount of data available on the role of biological markers. The objective of this study was to assess the expression of CD117 (c-KIT) in PT of the breast and its relationship with morphology and clinical outcome.

Methods

A total of 78 patients having available clinical records between 2004 and 2014 with breast PT were retrieved from the cancer registry at Shaukat Khanum Memorial Cancer Hospital and Research Centre, Lahore and were followed up. Immunohistochemical studies were performed on all the cases using mono­clonal antibody CD117 (DAKO A4502) using Leica Bond-Max automated biosystem (Leica Biosystems, Melbourne, Australia). Staining proportion and intensity of both epithelial and stromal elements were analyzed. Evaluation of the protein expression was determined and scored.

Results

Patients’ mean age was 45.13 ± 11.4 years. Thirty-nine (50.0%) patients had tumor on right side, 38 (48.7%) had on left and only one (1.3%) was bilateral. Thirty-two (41.0%) patients had benign PT, 21 (26.9%) had borderline and 25 (32.1%) had malignant PT. Negative CD117 expression was observed in 20 (62.5%), eight (38.0%) and 12 (48.0%) of benign, borderline and malignant PTs, respectively. Positive CD117 expression was observed in 12 (37.5%) benign, 13 (61.9%) borderline and 13 (52.0%) malignant PTs. There was insignificant association between CD117 expression with respect to tumor sub-type, patient’s age and clinical behavior (p-value > 0.05).

Conclusion

CD117 expression was not found to be associated with tumor type and was not associated with increased risk of recurrence in this sample of patients. Further work is needed to better understand the prognostic value of CD117 expression in breast PTs.

Fibroepithelial lesions revisited: implications for diagnosis and management

Fibroepithelial lesions of the breast, comprising the fibroadenoma and phyllodes tumour, are a unique group of neoplasms that share histological characteristics but possess different clinical behaviour. The fibroadenoma is the commonest benign breast tumour in women, while the phyllodes tumour is rare and may be associated with recurrences, grade progression and even metastasis. The diagnosis of fibroadenoma is usually straightforward, with recognised histological variants such as the cellular, complex, juvenile and myxoid forms. The phyllodes tumour comprises benign, borderline and malignant varieties, graded using a constellation of histological parameters based on stromal characteristics of hypercellularity, atypia, mitoses, overgrowth and the nature of tumour borders. While phyllodes tumour grade correlates with clinical behaviour, interobserver variability in assessing multiple parameters that are potentially of different biological weightage leads to significant challenges in accurate grade determination and consequently therapy. Differential diagnostic considerations along the spectrum of fibroepithelial tumours can be problematic in routine practice. Recent discoveries of the molecular underpinnings of these tumours may have diagnostic, prognostic and therapeutic implications.

Recurrence prediction for breast phyllodes tumours: validation of the Singapore nomogram in Korean women

AIM

The Singapore nomogram was developed to predict recurrence risk of phyllodes tumours (PTs) of the breast based on histological features of stromal atypia, stromal mitoses, stromal overgrowth and surgical margin status. We aimed to validate the utility of the Singapore nomogram in a Korean PT cohort.

METHODS

One hundred and twenty-four patients with Korean PT who underwent surgical resection between 1996 and 2015 were included in this study. Pathology reports and slides were reviewed to obtain histopathologic features and acquire Singapore nomogram scores. The probability of concordance between predicted and observed survivals by means of the Singapore nomogram was evaluated using a concordance index (C-index).

RESULTS

Of the 124 cases, 57 (46%) were diagnosed as benign, 50 (40.3%) as borderline and 17 (13.7%) as malignant. Recurrences occurred in 25 (20.2%) patients. Univariate analysis showed PTs with higher stromal mitotic counts, marked stromal cellularity, stromal overgrowth, positive surgical margin, marked stromal atypia or a malignant grade presented higher risks of recurrence. Multivariate analysis showed stromal mitoses and surgical margin status independently predicted recurrence-free survival. Patients with high nomogram scores were at greater risk of recurrence (HR=1.05, 95% CI: 1.02 to 1.07, p<0.001) with a C-index of 0.762.

CONCLUSION

The Singapore nomogram provided a useful means of predicting PT outcomes in a Korean PT cohort.

Extramammary Borderline Phyllodes Tumor Presenting as an Umbilical Mass

Phyllodes tumors (PTs) represent a spectrum of rare, fibroepithelial neoplasms of the breast, which can be subcategorized as benign, borderline, or malignant based on their histological appearance. Accessory breast tissue may present anywhere along the embryological mammary ridge, and at distant locations as aberrant breast tissue. We present the case of a 56-year-old lady with an umbilical mass, thought to represent a strangulated hernia. Sections showed a fibroepithelial tumor with leaf-like ducts, conspicuous mitotic activity (up to 8 per 10 high-power fields), and focal infiltration into fat. Immunohistochemical studies showed diffuse positivity of epithelial cells for estrogen receptor, mammaglobin, GCDFP-15, and CK7. These findings were consistent with a borderline PT. This is the first case report of PT presenting as an umbilical mass, and the first extramammary borderline PT described.

Expression of EMP1, EMP2, and EMP3 in breast phyllodes tumors

Purpose

Phyllodes tumors (PTs) are biphasic tumors accounting for 0.3–1.5% of all breast tumors. Epithelial membrane proteins (EMPs) have been reported in various malignant tumors but their expression in PTs is unclear. In this study, we aimed to evaluate the expression of EMP1, EMP2, and EMP3 in breast phyllodes tumors (PTs), and to investigate their clinical implications.

Methods

In total, 185 PTs were used for constructing a tissue microarray. Immunohistochemical staining for EMP1, EMP2, and EMP3 was performed, and the results were analyzed along with the clinicopathologic parameters.

Results

In total, 185 PTs were included in this study, and comprised 138 benign, 32 borderline, and 15 malignant PTs. In malignant PTs, the epithelial component showed decreased expression of EMP1 (P = 0.027), EMP2 (P = 0.004), and EMP3 (P = 0.032), compared to the benign and borderline PTs. Conversely, stromal component of borderline and malignant PTs showed higher expression of EMP1 (P = 0.027), EMP2 (P = 0.004), and EMP3 (P = 0.032) compared to benign PTs. Expression of EMP1 and EMP3 correlated positively with stromal cellularity and cellular atypia (P < 0.001). In the univariate analysis, stromal EMP3 was associated with shorter disease-free survival (P < 0.001), and shorter overall survival (P = 0.034).

Conclusion

The expression of EMP1, EMP2, and EMP3 is decreased in the epithelial component and is increased in the stromal component of PT with higher histologic grade. Thus, stromal EMP3 expression may serve as an independent prognostic factor in PT.

Phyllodes tumours of the breast: Outcomes and recurrence after excision

INTRODUCTION

Wide excision margins are traditionally recommended for phyllodes tumours of the breast to reduce recurrence. Recent studies suggest margin status and histopathological features, excluding margin width, influence recurrence. This study evaluated treatment outcomes for phyllodes tumours and examined predictors of recurrence.

METHODS

Clinical and follow-up information for phyllodes tumours patients treated between 2008 and 2017 were obtained from chart review. Tumour subtype and histopathological features were determined from pathology reports. Primary endpoints were recurrence rate and time to recurrence or mortality.

RESULTS

Among 96 patients, there were 6 local and 1 distant recurrences. Overall recurrence rate was 7.3% and average time-to-recurrence was 13.7 months. Tumour size, margin status, necrosis, and mitoses were associated with recurrence; margin width was not. Two deaths (2.1%) from malignant phyllodes occurred.

CONCLUSIONS

Multiple histopathological features influence phyllodes recurrence. Wide excision and re-excising positive margins for benign tumours was not beneficial.

Accuracy of p53 and ki-67 in the graduation of phyllodes tumor, a model for practical application

Background

The accurate graduation of a phyllodes tumor (PT) is critical for effective treatment as it allows correct surgical management, and avoids inadequate excision for malignant or borderline PT, or surgical overtreatment in benign PT. PTs of the breast are notoriously difficult to classify, and reliable differentiation of a benign PT from a borderline or malignant PT can be problematic, especially among relatively inexperienced pathologists. Although several authors acknowledge a strong relationship between the immunohistochemical expression of p53 and Ki-67 and the histopathological grade of PT—with potential impact on diagnostic accuracy—the literature lacks consensus about which cutoff defines a positive index test. The objective of this study is to establish a practical application score that increases the graduation accuracy of PT through the appropriate use of these auxiliary methods.

Methods

A retrospective study cohort of 146 pathology reviewed PTs surgically removed between January 2000 and December 2015. The Ki-67 test was considered positive if > 10% of neoplastic cells showed nuclear staining. The p53 test was considered positive if > 10% of neoplastic nuclear cells showed nuclear staining in a moderate or strong intensity.

Results

Of the 146 PT cases reviewed, 110 were classified as benign, 16 as borderline, and 20 as malignant. The correlation between age and size with benign, borderline, and malignant subgroups was statistically significant (p < 0.001). Significance was observed in the expression of both Ki-67 and p53 in the comparison of benign, borderline, and malignant PT with p < 0.001 and a 95% confidence interval (CI). When correlating the presence of positivity in either of the two index tests with the diagnosis of borderline or malignant PT, we reached a sensitivity of 100% and a specificity of 91.8 (p < 0.001; 95% CI).

Conclusion

We propose a practical methodology to achieve an accurate grade of PT, based on clearly defined and easy to apply cutoffs of a simple immunohistochemical panel of Ki-67 and p53. A PT positive for either of the index tests should be graded as borderline or malignant, so pathologists can use this test to improve accuracy. We hope this new approach might provide the basis for the development of standardization in using p53 and Ki-67 for grading PT.

Predicting Outcome in Mammary Phyllodes Tumors: Relevance of Clinicopathological Features

BACKGROUND

Phyllodes tumors (PTs) of the breast are uncommon fibroepithelial neoplasms. Most behave in a benign fashion but they also have the potential to recur locally or to metastasize.

METHODS

In the current study involving 290 PTs (181 benign, 76 borderline, and 33 malignant) from three hospitals over an 11-year period, we assessed the relationship between histologic parameters (including histologic features affecting grade and surgical margin status), postoperative adjuvant treatment, and local recurrences and distant metastases.

RESULTS

An involved surgical margin was the only factor associated with increased risk of local recurrences (hazard ratio [HR] 4.673, p = 0.003), but not for distant metastases. For local recurrences, a wider margin did not confer additional benefits. None of the histologic factors were predictive for local recurrences. In contrast, distant metastases were correlated with histologic parameters, particularly an infiltrative border (HR 10.935, p = 0.012) and the presence of necrosis (HR 15.311, p = 0.007). In this series, all local recurrences were found in patients without radiotherapy, regardless of surgical margin status.

CONCLUSION

A negative surgical margin is mandatory for the effective local control of PT recurrence, and a minimal margin clearance may be sufficient. For distant metastases, the inherent characteristics of PTs are important, thus it may be prudent to evaluate additional histologic features, including necrosis, for patients' prognostication.

Local Recurrence of Benign, Borderline, and Malignant Phyllodes Tumors of the Breast: A Systematic Review and Meta-analysis

BACKGROUND

This systematic review and meta-analysis aimed to investigate local recurrence (LR) rates among the three grades (benign, borderline, and malignant) of phyllodes tumors (PTs). The study also assessed various risk factors for LR.

METHODS

Electronic articles published between 1 January 1995 and 31 May 2018, were searched and critically appraised. The authors independently reviewed the abstracts and extracted data for LR rates and LR risk factors.

RESULTS

The review incorporated 54 studies with 9234 individual cases. The pooled LR rates were 8% for benign, 13% for borderline, and 18% for malignant PTs. The risk of LR was significantly increased by borderline versus benign PTs (odds ratio [OR] 2.00; 95% confidence interval [CI] 1.68-2.38) and malignant versus borderline PTs (OR 1.28; 95% CI 1.05-1.55). The significant risk factors for LR were mitoses, tumor border (infiltrating vs. pushing), stromal cellularity (moderate/severe vs. mild), stromal atypia (severe vs. mild/absent), stromal overgrowth (severe vs. mild/absent), and tumor necrosis (positive vs. negative). Age and tumor size were not associated with LR risk. The subgroup analysis showed that breast-conserving surgery versus mastectomy and positive versus negative surgical margins were significantly associated with an increased LR risk only in malignant PTs.

CONCLUSIONS

The risk of LR was significantly increased from benign to borderline to malignant PTs. Mitoses, tumor border, stromal cellularity, stromal atypia, stromal overgrowth, tumor necrosis, type of surgery, and surgical margin status may be risk factors for LR. Different management strategies could be considered for different PT grades.