Breast sarcomas and malignant phyllodes tumours: comparison of clinicopathological features, treatment strategies, prognostic factors and outcomes

Targeted DNA Sequencing in Diagnosis of Malignant Phyllodes Tumors With Emphasis on Tumors With Keratin and p63 Expression

The differential diagnosis of malignant spindle cell neoplasms in the breast most frequently rests between malignant phyllodes tumor (MPT) and metaplastic carcinoma (MBC). Diagnosis of MPT can be challenging due to diffuse stromal overgrowth, keratin (CK) and/or p63 immunopositivity, and absent CD34 expression, which can mimic MBC, especially in core biopsies. Distinction of MPT from MBC has clinical implications, with differences in surgical approach, chemotherapy, and radiation. In this study, we evaluated MPTs (78 tumors, 64 patients) for stromal CK, p63, and CD34 expression and profiled a subset (n = 31) by targeted next-generation DNA sequencing, with comparison to MBC (n = 44). Most MPTs (71%) were CK+ and/or p63+, including 32% CK+ (25/77 focal) and 65% p63+ (32/66 focal, 10/66 patchy, and 1/66 diffuse). Thirty percent of MPTs expressed both CK and p63 (20/66), compared with 95% of MBCs (40/42, P < .001). CK and/or p63 were positive in CD34+ and CD34- MPTs. Recurrent genetic aberrations in MPTs involved TERT, TP53, MED12, CDKN2A, chromatin modifiers, growth factor receptors/ligands, and phosphoinositide-3 kinase (PI-3K) and MAPK pathway genes. Only MED12 (39%, 12/31) and SETD2 (13%, 4/31) were exclusively mutated in MPTs and not MBCs (P < .001 and P = .044, respectively), whereas PIK3R1 mutations were only found in MBCs (37%, 13/35, P < .001). Comparative literature review additionally identified ARID1B, EGFR, FLNA, NRAS, PDGFRB, RAD50, and RARA alterations enriched or exclusively in MPTs vs MBCs. MED12 was mutated in MPTs with diffuse stromal overgrowth (53%, 9/17), CD34- MPTs (41%, 7/17), and CK+ and/or p63+ MPTs (39%, 9/23), including 36% of CD34- MPTs with CK and/or p63 expression. Overall, MED12 mutation and/or CD34 expression were observed in 68% (21/31) MPTs, including 61% (14/23) of CK+ and/or p63+ tumors. Our results emphasize the prevalence of CK and p63 expression in MPTs and demonstrate the diagnostic utility of next-generation DNA sequencing, especially in MPTs with confounding factors that can mimic MBC.

Primary breast sarcomas: A 13 case-series study treated in university hospital in central Tunisia over a 25-year period

AIM

To retrospectively study the therapeutic modalities of primary breast sarcomas in view of the data of a local Tunisian experience.

METHODS

It is a monocentric, descriptive, retrospective study including 13 cases of primary breast sarcoma treated over a period of 25 years (1995-2020) in the oncological radiotherapy department of a university hospital in Sousse, Tunisia.

RESULTS

In our study, 13 cases of non-metastatic breast sarcomas that has been identified, divided into ten cases of phyllodes sarcomas and three cases of non-phyllodes sarcomas.Surgically, all our patients had a mastectomy. Among them, seven underwent a lymph node procedure: five underwent axillary lymph node dissection, and two others had primary axillary lymph node biopsy. For the adjuvant treatment, all the patients included in our study received radiotherapy and seven received chemotherapy. Local recurrence occurred on the operative scar in one patient after completion of radiation therapy. Metastatic relapse was described in five patients. The time to onset of metastases varied between two months and five years. Nevertheless, a complete remission was noted in 6 patients with a follow-up varying from four years to 20 years. Two patients were lost to follow-up.

CONCLUSION

Breast sarcomas remain a very rare entity of aggressive tumors.The therapeutic approach is poorly codified. For this reason, the therapeutic decision should always be discussed in a multidisciplinary assessment.

Clinical perspectives and outcomes of the giant breast phyllodes tumor and sarcoma: a real-world retrospective study

BACKGROUND

Giant breast malignant phyllodes tumor or sarcoma (GBPS) are rare entities with diameter larger than 10 cm and variously histological pleomorphisms. This disease poses a significant threat to the quality of life of individuals, and its prognosis remains unclear. This study aimed to explore the differential diagnosis, treatment, and prognosis of GBPS in a real-world retrospective cohort.

METHODS

We collected GBPS (diameter > 10 cm, n = 10) and BPS (diameter ≤ 10 cm, n = 126) from patients diagnosed with sarcoma or malignant phyllodes tumor between 2008 and 2022. We analyzed clinical characteristics, histological status, treatment, and local recurrence using the Fisher's exact test between GBPS (diameter > 10 cm) and BPS (diameter ≤ 10 cm) cohort. We described overall survival (OS) and disease-free survival (DFS) using Kaplan-Meier curves and identified risk factors for local recurrence using logistic regression. The tumor size, age at diagnosis, and differential immunohistochemistry markers of breast sarcoma or phyllodes tumor to determine the prognosis of GBPS.

RESULTS

In our retrospective analysis of breast malignancies, we identified 10 cases of GBPS and 126 cases of BPS, corresponding to a GBPS prevalence of 0.17% (10/6000). The median age was 38.5 years (inter-quartile range, IQR: 28.25-48.5 years). During the follow-up of period (median: 80.5 months, IQR: 36.75-122 months), the local recurrence (LR) rate was 40% and 20.6%, respectively. Clinical characteristics of young age (HR:2.799, 95%CI -00.09276-0.017, p < 0.05) and cytological characteristics of marked stromal atypia (HR:0.88, 95% CI 0.39-1.40, p < 0.05) were risk factors for the poor prognosis of GBPS by COX regression model analysis. The Kaplan-Meier curves of GBPS 5-year disease-free survival (DFS) and overall survival (OS) were 31.5 months and 40 months, respectively, and were not associated with adjuvant radiation or chemotherapy.

CONCLUSION

We recommend mastectomy with a clear surgical margin as the preferred treatment for GBPS. Age and stromal atypia are significantly associated with recurrence. Adjuvant radiation therapy is advised; however, there was no improvement in overall survival. There is no consensus on the effectiveness of adjuvant chemotherapy and genetic methods, highlighting the need for further research into this aggressive tumor. We recommend a multidisciplinary approach involving a dedicated team for the management of GBPS.

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.

A malignant transformation of borderline phyllodes tumor to fibrosarcoma breast: A rare case report

ABSTRACT

Phyllodes tumor of the breast with malignant transformation to fibrosarcoma of the breast is a rare entity. Breast fibrosarcoma is uncommon, accounting for less than 1% of all breast tumors. Prognosis of fibrosarcoma of the breast is poor. Due to its rarity, survival rates are not defined. A 23-year-old woman presented with a mass in the left breast, and another 48-year-old woman presented with right breast mass. Both patients underwent for surgery. The histological & immunohistochemical examination confirms the diagnosis of a malignant transformation from borderline phyllodes tumor to fibrosarcoma. We concluded that the phyllodes tumor is mostly benign but local recurrence is common. As the tumor progresses toward malignancy, due to the difficulty in the diagnosis of borderline phyllodes tumors, total mastectomy with axillary resection must be recommended.

Survey of recurrent diagnostic challenges in breast phyllodes tumours

BACKGROUND

Breast phyllodes tumours (PTs) are graded as benign, borderline, or malignant by analysis of multiple histological features. PT grading is often inconsistent, likely due to variation in the weighting of grading criteria by pathologists.

DESIGN

The hierarchy of use of diagnostic criteria was identified using a 20-question survey.

RESULTS

In all, 213 pathologists from 29 countries responded. 54% reported 10-50 PT cases per year. Criteria considered key to PT diagnosis were: increased stromal cellularity (84.3%), stromal overgrowth (76.6%), increased stromal mitoses (67.8%), stromal atypia (61.5%), stromal fronding (59.0%), periductal stromal condensation (58.0%), irregular tumour borders (46.3%), and/or lesional heterogeneity (33.7%). The importance of grading parameters were: mitotic activity (55.5%), stromal overgrowth (54.0%), stromal atypia (51.9%), increased stromal cellularity (41.7%), and nature of the tumour border (38.9%). 49% would diagnose malignant PT without a full array of adverse features. 89% used the term "cellular fibroepithelial lesion (FEL)" for difficult cases; 45% would diagnose an FEL with stromal fronding (but lacking other PT features) as fibroadenoma (FA), 35% FEL, and 17% PT. 59% deemed clinico-radiological findings diagnostically significant; 68% considered age (≥40 years) important in determining if an FEL was a FA or PT. In FELs from young patients, increased stromal cellularity (83%), fronding (52%), and mitoses (41%) were more common. 34% regarded differentiating cellular FA from PT as a specific challenge; 54% had issues assigning a borderline PT grade.

CONCLUSION

Criteria for grading PT lie on a spectrum, leading to interpretive variability. The survey highlights the criteria most used by pathologists, which do not completely align with WHO recommendations.

Malignant phyllodes tumor and primary breast sarcoma; distinct rare tumors of the breast

BACKGROUND

Malignant phyllodes (MP) and primary breast sarcomas (PBS) are rare neoplasms with overlapping histopathologic features. We compared overall survival (OS) and estimated the association of surgery and therapies with OS.

METHODS

We utilized the National Cancer Database (2004-2016). Patients without surgery, unknown surgery, or margins, or Stage IV disease were excluded. Kaplan-Meier curves and Cox proportional hazards models were used to estimate unadjusted and adjusted OS, respectively.

RESULTS

A total of 3209 (59.5%) MP, and 2185 (40.5%) PBS were identified. Despite a larger median tumor size in MP (46 vs. 40 mm PBS, p < 0.001), lumpectomy rate was higher for MP (52.9% vs. 27.0% PBS, p < 0.001). Compared to MP, PBS patients more frequently received radiation (28.9% vs. 24%), and chemotherapy (28.1% vs. 4%), both p < 0.001. Unadjusted OS was lower for PBS (57% vs. 85% MP, log-rank p < 0.001). PBS (vs. MP) had persistently worse survival (hazard ratio [HR]: 1.98, 95% confidence interval [CI]: 1.69-2.31) after adjustment. Receipt of adjuvant therapies was not associated with OS (either neoplasm); however, lumpectomy was associated with improved OS (vs. mastectomy) for both PBS (HR: 0.59, 95% CI: 0.50-0.75) and MP (HR: 0.65, 95% CI: 0.53-0.81). Positive margins had no association with OS for MP (HR: 1.09, 95% CI: 0.75-1.60), but was associated with worse survival for PBS (HR: 2.35, 95% CI: 1.82-3.02).

DISCUSSION

We found significant survival differences between MP and PBS, with PBS having a consistently worse OS. Our findings support surgery as the mainstay of treatment for both tumor types and suggest that lumpectomy may be a reasonable option for select patients without compromising outcomes.

Fibroepithelial tumours of the breast-a review

Fibroepithelial tumours of the breast are biphasic neoplasms composed of both epithelial and stromal elements, including the common fibroadenoma and the infrequent phyllodes tumour. The admixture of epithelium and stroma in the fibroadenoma shows intra- and pericanalicular patterns, and may display a variety of histological changes. Fibroadenoma variants include the cellular, juvenile, myxoid and complex forms. The cellular fibroadenoma may be difficult to distinguish from the benign phyllodes tumour. Stromal mitotic activity can be increased in fibroadenomas in the young and pregnant patients. Phyllodes tumours, neoplasms with the potential for recurrence, show an exaggerated intracanalicular growth pattern with broad stromal fronded architecture and stromal hypercellularity. They are graded into benign, borderline and malignant forms based on histological assessment of stromal features of hypercellularity, atypia, mitotic activity, overgrowth and the nature of the tumour borders. Classification of phyllodes tumours is imperfect, compounded by tumour heterogeneity with overlapping microscopic features among the different grades, especially in the borderline category. Malignant phyllodes tumours can metastasise and cause death. Determining which phyllodes tumours may behave aggressively has been difficult. The discovery of MED12 mutations in the pathogenesis of fibroepithelial tumours, together with other gene abnormalities in the progression pathway, has allowed refinements in diagnosis and prognosis.

Outcomes of systemic therapy in metastatic phyllodes tumor of the breast

PURPOSE

Metastatic phyllodes tumors of the breast (MPT) are rare breast neoplasms, limiting development of standardized treatment approaches. We sought to characterize the largest group of MPT thus far reported, evaluating systemic therapy outcomes.

METHODS

Adult patients diagnosed with MPT between 1993 and 2015 and followed at MD Anderson Cancer Center were selected for retrospective chart review. Systemic therapy was sorted into: adriamycin/ifosfamide (AI), other anthracycline regimens, other ifosfamide regimens, gemcitabine-based regimens, and other. Given one patient may have received more than one regimen, we assumed that the effects of each regimen were independent from previous therapy. Median overall survival (OS) and progression-free survival (PFS) were estimated by the Kaplan-Meier method. Log-rank test was performed to evaluate the difference in OS between patient characteristics groups, and the differences in PFS between the five chemotherapy regimens.

RESULTS

We identified 50 MPT patients, with 31 patients receiving 61 systemic regimens. Median OS was 10.7 months (95% CI: 8.67, 16.5). AI had a PFS of 9.10 months (95% CI: 5.03, 14.2), other ifosfamide regimens had a PFS of 5.10 months (95% CI: 0.67, 12.1), other anthracycline regimens had a PFS of 3.65 months (95% CI: 1.17, 7.90), gemcitabine-based regimens had a PFS of 2.80 months (95% CI: 1.83, 4.60), and other regimens had a PFS of 1.67 months (95% CI: 1.13, 7.77).

CONCLUSION

MPT patients are a unique population with limited characterization to date. Our study demonstrates activity of multiple sarcoma-directed chemotherapy regimens, with ifosfamide-containing regimens having the longest PFS.

Retrospective study of malignant phyllodes tumors of the breast: Younger age, prior fibroadenoma surgery, malignant heterologous elements and surgical margins may predict recurrence

Purpose

The potential recurrence rate of malignant phyllodes tumors (MPTs) of the breast is high, and the prognostic factors are still unclear. We therefore aim to study the factors affecting the outcome of MPTs.

Methods

A retrospective review of MPT patients treated from 2006 to 2020 at our institution was conducted. Univariate and multivariate Cox proportional hazard models were used to examine the influence of different variables on RFS. Moreover, significant prognostic factors were combined to construct the nomogram to predict the probability of relapse occurring in MPT patients. The 5-year and 10-year RFS rates were estimated using the Kaplan–Meier method.

Results

During the study period, 188 MPT patients were identified. The presence of malignant heterologous elements was observed in 23 (12.2%) patients with MPT, and the patients with malignant heterologous elements who received chemotherapy had longer RFS, which could reduce the risk of recurrence (p = 0.022). Recurrence occurred in 56/188 (29.8%) patients, of whom 47 experienced local recurrence and 11 experienced distant metastases. The 5-year and 10-year cumulative RFS rates were 77.5% and 70.1%, respectively. Age (p = 0.041), fibroadenoma surgery history (p = 0.004), surgical margins (p = 0.001) and malignant heterologous elements (p < 0.001) were independent risk factors for postoperative RFS. Subsequently, a nomogram was built, with a C-index of 0.64 (95% CI: 0.629–0.661), to predict the risk of recurrence.

Conclusion

The results of this study showed that younger age, fibroadenoma surgery history, malignant heterologous elements and surgical margins <1 cm predict a higher incidence of recurrence in MPT patients. Patients with malignant heterologous elements treated with chemotherapy could have a reduced risk of recurrence.

•

This is the largest cohort of malignant phyllodes tumors in China.

•

Age, fibroadenoma surgery history, surgical margins and malignant heterologous elements predict the risk of recurrence.

•

Patients with malignant heterologous elements treated with chemotherapy could reduce the risk of recurrence.

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.

En Bloc Excision of Phyllodes Tumor of the Breast: Radical Approach Heralds Better Outcome

INTRODUCTION

Surgery is the primary treatment of phyllodes tumor of the breast, and margins are the most important risk factor associated with local recurrence. We conducted a retrospective audit of 433 patients treated at our center.

PATIENTS AND METHODS

Women who presented with phyllodes tumors between 1999 and 2017 were included in the analysis. Data was collected from the hospital medical records, telephonic interviews, and electronic mail.

RESULTS

Of the 433 women included in this study, 177 (40.9%) had benign phyllodes tumors, 84 (19.4%) were borderline, 131 (30.3%) were malignant, and 41 (9.5%) had sarcoma. A history of previous excision was noted in 154 (35.6%) patients, of which 104 presented with local recurrence. Of the total patients, 209 (48.3%) underwent breast conservation surgery; the median pT was 6 cm. At a median follow-up of 37.9 months, the 5-year disease-free survival (DFS) was 82.9%. On multivariate analysis, the factors that impacted DFS were histology (hazard ratio, 4.1; 95% confidence interval [CI], 1.5-10.9; P = .005) and history of previous excision biopsy (hazard ratio, 3.39; 95% CI, 1.76-6.52; P < .001). We analyzed 231 women who presented without any prior excision separately, wherein at a median follow-up of 44.1 months, the DFS was 92.1% (95% CI, 92.05%-92.15%). In addition, less recurrences were noted in this cohort (5.6% [13/231] in no-excision biopsy vs. 12.5% with surgery done prior to presentation to our institute).

CONCLUSION

A previous history of excision and the histologic subtype of phyllodes tumor are factors that have an impact on DFS, thus emphasizing the need for appropriate surgical planning and en bloc excision of the phyllodes at presentation.

Phyllodes tumors of the breast. The treatment results for 340 patients from a single cancer centre

PURPOSE

The primary treatment of choice for patients with phyllodes tumor of the breast (PTB) is surgery. Two major problems regarding the treatment of such patients remain unclear: what is the appropriate surgical margin and what role is played by adjuvant radiotherapy (ART).

METHODS

The study provides a retrospective review of all patients with PTB treated between 1952 and 2013 at a single institute. The histology slides were re-examined based on WHO criteria. The clinical characteristics and therapy outcomes were obtained. The five-year survival with no evidence of disease (NED) was used as the end point.

RESULTS

The study population comprised 340 women with PTB. Fifty-five percent of the patients were diagnosed with the benign, 11.8% with borderline and 33.2% with malignant PTB. All the patients received primary treatment with surgery (mastectomy-27.1%, and BCS- 72.9%). Local recurrence (LR) was found in 28 (9.1%) of these patients. Four patients with borderline and 8 with malignant PTB who were treated with BCS and had tumor-free margins < 1 cm received ART. None of these patients had LR and all survived 5 years NED. Of the 340 patients from our group, 294 (86.4%) survived five-years NED.

CONCLUSION

The prognosis for benign PTB is excellent and can be cured with surgery alone. A sufficient margin would be 0.1 cm (data from the literature) or 0.2-0.4 cm (our study). We recommend application of ART for such patients but the role of ART in patients with borderline and malignant PTB treated with BCS and with surgical margin < 1 cm remains uncertain.

Fibroepithelial lesions; The WHO spectrum

Fibroepithelial lesions of the breast comprise a morphologically and biologically heterogeneous group of biphasic tumors with epithelial and stromal components that demonstrate widely variable clinical behavior. Fibroadenomas are common benign tumors with a number of histologic variants, most of which pose no diagnostic challenge. Cellular and juvenile fibroadenomas can have overlapping features with phyllodes tumors and should be recognized. Phyllodes tumors constitute a spectrum of lesions with varying clinical behavior and are graded as benign, borderline or malignant based on a set of histologic features according to recommendations by the World Health Organization (WHO). Recent developments have significantly expanded our understanding of the pathogenesis of fibroepithelial lesions, highlighting fibroadenomas as true neoplasms and underscoring a commonality with phyllodes tumors in the form of recurrent MED12 exon 2 mutations. In addition, sequencing studies have elucidated pathways associated with phyllodes tumor progression. Accurate diagnosis and grading of phyllodes tumors are important for patient management and prognosis, as grade broadly correlates with increasing local recurrence risk, and essentially only malignant tumors metastasize. However, classification of fibroepithelial lesions in many cases remains challenging on both core biopsy and excision specimens. A commonly encountered problem at the benign end of the spectrum is the distinction of benign phyllodes tumor from cellular fibroadenoma, which is largely due to the subjective nature of histologic features used in diagnosis and histologic overlap between lesions. Grading is further complicated by the requirement to integrate multiple subjective and ill-defined parameters. On the opposite end of the histologic spectrum, malignant phyllodes tumors must be distinguished from more common metaplastic carcinomas and from primary or metastatic sarcomas, which can be especially difficult in core biopsies. Immunohistochemistry can be useful in the differential diagnosis but should be interpreted with attention to caveats. This review provides an overview and update on the spectrum of fibroepithelial lesions, with special emphasis on common problems and practical issues in diagnosis.