Primary malignant phyllodes tumors of the breast: A retrospective analysis from a referral center

Prognostic factors and treatment insights for metastatic malignant phyllode tumors

BACKGROUND

The aim of this study is to contribute a better understanding of metastatic malignant phyllode tumors (MMPTs) by exploring its prognostic factors, describing treatment landscape, and providing optimal treatment choices.

METHODS

This retrospective multicentric study was included 43 patients with MMPTs who received treatment from 2009 to 2023 in four centers. The primary endpoint of the study was overall survival (OS).

RESULTS

The median overall survival of these patients was 7.27 months (range: 0.63-118.53) and the median follow-up time was 16.8 months (range: 2-188). The median age of these patients were 49 years. The median metastasis-free survival (MFS, it is the time between initial diagnosis and diagnosis of metastatic disease) was 7.27 months, and the most common site of metastasis was lung (35/43, 81.4 %). Treatment for MMPTs primarily consisted of systemic chemotherapy and metastasectomy. Multivariate analysis revealed that chemotherapy after metastasis (HR = 0.250, 95 % CI 0.109-0.571; P = 0.001) and MFS >6 months (HR = 0.407, 95 % CI 0.198-0.836; P = 0.014) were independently associated with OS. The most common chemotherapy regimen was anthracyclines along with ifosfamide (AI), with the median progression-free survival of 5.5 months. Metastasectomy did not significantly improve OS.

CONCLUSION

The study findings highlight the significance of systemic treatment (chemotherapy) and the impact of MFS on prognosis of MMPTs. For these patients, systemic treatment may improve survival outcomes. And patients with MFS <6 months appear to have a poorer prognosis.

Malignant phyllodes tumours of the breast: the case for revising WHO's 'full house' diagnostic criteria

Phyllodes tumours (PTs) of the breast present diagnostic challenges due to their complex histological features and potential for malignant behaviour. The World Health Organisation (WHO) classification requires the presence of five adverse histological criteria to categorise PTs as malignant, aiming to avoid overdiagnosis and improve diagnostic consistency. However, emerging evidence suggests that these strict criteria may underdiagnose tumours with metastatic potential and histological features that would otherwise be considered malignant in soft tissue tumours, leading to significant implications for prognosis and treatment. Recent studies have highlighted cases where tumours classified as borderline PT by WHO criteria exhibited metastatic behaviour, emphasising the need to refine the diagnostic framework. Microscopic criteria used to classify PT also vary among reporting pathologists, resulting in suboptimal reproducibility. This review examines the histological parameters utilised in the classification of malignant PT, highlights existing evidence gaps and analyses international breast pathologist survey data to propose a pragmatic diagnostic approach. We recommend redefining malignant PTs to include cases meeting four of the five WHO criteria, supplemented by comprehensive sampling and clinical context. This approach balances the risk of underdiagnosis with the need for standardised, reproducible diagnostic practices. Future collaborative efforts should focus upon developing evidence-based, biologically relevant classification systems and leveraging technological advancements to enhance diagnostic precision. These efforts aim to refine classification, improve prognostic accuracy and optimise patient management strategies.

Patient-derived organoid models of malignant phyllodes tumours for drug sensitivity testing and identification of targeted therapeutic strategies

BACKGROUND

Malignant phyllodes tumours (MPT) of the breast are rare fibroepithelial neoplasms. It exhibits rapid growth, large size, and a high local recurrence rate.

METHODS

In this study, we established novel patient-derived organoid (PDO) models from two primary MPT samples and conducted comprehensive genetic profiling and drug screening.

RESULTS

The PDO models faithfully recapped the histopathological and molecular features of the primary tumours, including stromal overgrowth, leaf-like projections, and the expression of key diagnostic markers. Drug testing revealed significant heterogeneity in response profiles to chemotherapeutic reagents between the two MPT-derived organoids, implying the importance of personalised drug testing. Next-generation sequencing analysis identified recurrent mutations in TP53, RB1, EGFR, ATM, and RECQL4, which correlated with the drug sensitivity profiles observed in the organoid models. Targeted therapeutic drugs, such as Abemaciclib (targeting the RB1 pathway) with an IC50 value of 1.744 µM, and Alflutinib Mesylate (targeting the EGFR pathway) with an IC50 value of 0.9150 µM, exhibited significant cytotoxic effects in the MPT2 organoid models.

CONCLUSIONS

This study highlights the novel application of PDOs for studying the molecular landscape of MPTs and identifying effective therapeutic targets, offering a promising platform for guiding personalised treatment strategies for this rare and challenging cancer.

The pathologic and genomic evolution of primary malignant phyllodes tumors of the breast: retrospective cohort study and case-control genomic analysis

BACKGROUND

In patients with phyllodes tumors of the breast, the presence of mediator of RNA polymerase II transcription subunit 12 homolog mutations (MED12m) and a history of previous fibroadenoma may predict better outcomes. To aid in the prognostication of malignant phyllodes tumors of the breast (B-MPT), we assessed the prognostic value of fibroadenoma-like areas (supposed to have stemmed from a pre-existing fibroadenoma) and MED12m, in patients with resected primary B-MPTs.

METHODS

We conducted a single-center, retrospective, cohort study including all consecutive patients aged ≥18 years old, with non-metastatic B-MPT, who underwent surgery from January 2000 to December 2021. The endpoints were the cumulative incidences of all recurrences, according to the presence of fibroadenoma-like areas, reviewed by 3 reference pathologists. A nested, case-control genomic analysis was performed to evaluate the association between MED12m, the presence of fibroadenoma-like areas, and cancer recurrences.

RESULTS

Eight-nine patients were included, with 47% of tumors exhibiting Fibroadenoma-Like Areas (FLA+). These areas were not significantly associated with local recurrence (5-year cumulative incidence in FLA+ vs FLA-: 13.0, 95%CI [4.6-25.9] vs 23.6, 95%CI [11.9-37.5]; P = .14) or distant recurrence (5-year cumulative incidence in FLA+ vs FLA-: 12.5, 95%CI [4.5-25.0] vs 8.9, 95%CI [2.8-19.5], P = .61), at a median follow-up of 6.7 years. MED12m was not associated with distant recurrences or the presence of fibroadenoma-like areas.

CONCLUSIONS

Half of B-MPTs are characterized by the presence of fibroadenoma-like areas. This pathologic feature is not significantly associated with lower distant and local recurrences nor with the presence of MED12 mutations.

Bestatin attenuates breast cancer stemness by targeting puromycin-sensitive aminopeptidase

Breast cancer is a prevalent malignant tumor among women with an increasing incidence rate annually. Breast cancer stem cells (BCSCs) are integral in impeding tumor advancement and addressing drug resistance. Bestatin serves as an adjuvant chemotherapy, triggering apoptosis in cancer cells. In this study, the effects of bestatin on sorted BCSCs from breast cancer cell lines have been studied. Our results indicated that bestatin inhibits the migration and proliferation of breast cancer cells by reducing the stemness of BCSCs both in vitro and in vivo. Puromycin-sensitive aminopeptidase is implicated in the process through the regulation of cell cycle, resulting in heightened cell apoptosis and diminished cell proliferation of BCSCs. Our study suggest that targeting cancer stem cell may offer a promising approach in breast cancer treatment, presenting noval therapeutic strategies for patients with breast cancer.

Real-world data on malignant and borderline phyllodes tumors of the breast: A population-based study of all 921 cases in the Netherlands (1989 -2020)

AIM

The aim of our study is to analyze patterns in treatment and outcome in a population-based series of patients with borderline and malignant phyllodes tumors (PT).

MATERIAL AND METHODS

Data on all patients with a borderline or malignant PT (1989-2020) were extracted from the Netherlands Cancer Registry and the Dutch nationwide pathology databank (Palga) and retrospectively analyzed.

RESULTS

We included 921 patients (borderline PT n = 452 and malignant PT n = 469). Borderline PT patients more often had breast-conserving surgery (BCS) as final surgery (81 vs. 46%). BCS rates for borderline PT increased over time (OR 1.08 per year, 95%CI 1.04 - 1.13, P < 0.001). In malignant PT adjuvant radiotherapy was given in 14.7%; this rate increased over time (OR 1.07 per year, 95%CI 1.02 - 1.13, P = 0.012). Local recurrence rate (5-year estimate of cumulative incidence) was 8.7% (95%CI 6.0-11.4) for borderline PT and 11.7% (95%CI 8.6-14.8) for malignant PT (P = 0.187) and was related to tumor size ≥ 20 mm (HR 10.6 (95%CI 1.5-76.8) and positive margin (HR 3.0 (95%CI 1.6-5.6), p < 0.001), but not to negative margin width (HR 1.3 ( 95%CI 0.7-2.3), p = 0.350)). Distant metastasis occurred only in malignant PT with a 5-year cumulative incidence of 4.7% (95%CI 3.3 - 6.1).

CONCLUSION

This population-based series showed an increase in BCS in borderline PT and an increase in adjuvant radiotherapy in malignant PT over time. We identified malignant PT, BCS, larger tumor size and positive final margins as possible risk factors for local recurrence. Small but negative margins can be accepted.