E418: Non-metastatic malignant phyllodes tumors of the breast (B-MPT): a retrospective analysis from a referral center

ePoster Abstract Author(s)

Elisabetta Pennacchioli

Director
Istituto Europeo di Oncologia
milano, Italy

Submitter(s)

Elisabetta Pennacchioli

Director
Istituto Europeo di Oncologia
milano, Italy

Author(s)

CV

Carmine Valenza, MD

MD
Division of New Drugs and Early Drug Development for Innovative Therapies, European Institute of Oncology, IRCCS, Milan, Italy, United States
tD

tommaso martino De Pas, MD

MD
Head of Medical Oncology Division, Gavazzeni hospital, Bergamo, United States
AG

Aurora Gaeta, PhD

PhD
Department of Experimental Oncology, European Institute of Oncology, IRCCS, Milan, Italy, United States
GC

Grazia Castellano, MD

MD
Division of New Drugs and Early Drug Development for Innovative Therapies, European Institute of Oncology, IRCCS, Milan, Italy, United States
cs

celeste santoro, MD

MD
Division of New Drugs and Early Drug Development for Innovative Therapies, European Institute of Oncology, IRCCS, Milan, Italy, United States
ac

amedeo corona, MD

MD
Division of Melanoma, Soft Tissue Sarcomas and Rare Tumors, European Institute of Oncology, IRCCS, Milan, Italy, United States
gc

giulia chiappini, MD

MD
Division of Melanoma, Soft Tissue Sarcomas and Rare Tumors, European Institute of Oncology, IRCCS, Milan, Italy, United States
gv

grazia vivanet, MD

MD
Division of New Drugs and Early Drug Development for Innovative Therapies, European Institute of Oncology, IRCCS, Milan, Italy, United States
dt

dario trapani, MD

MD
Division of New Drugs and Early Drug Development for Innovative Therapies, European Institute of Oncology, IRCCS, Milan, Italy, United States
sc

sara coppola, MD

MD
Division of Melanoma, Soft Tissue Sarcomas and Rare Tumors, European Institute of Oncology, IRCCS, Milan, Italy, United States
fc

fabio conforti, MD

MD
Medical Oncology, Gavazzeni hospital, Bergamo, United States
dm

denise mattar, MD

MD
Division of Breast Surgery, European Institute of Oncology, IRCCS, Milan, Italy, United States
sg

sara gandini, PhD

PhD
Department of Experimental Oncology, European Institute of Oncology, IRCCS, Milan, Italy, United States
pv

paolo veronesi, MD

MD
Head, Division of Breast Surgery, European Institute of Oncology, IRCCS, Milan, Italy, United States
gc

giuseppe curigliano, MD

MD
Head, Division of New Drugs and Early Drug Development for Innovative Therapies, European Institute of Oncology, IRCCS, Milan, Italy, United States

Introduction: Background: B-MPT accounts for < 1% of breast neoplasms. The standard treatment for non-metastatic disease consists of wide local excision. Type of excision and adjuvant treatments are still matter of debate. Because of its rarity, only few case series with less than 100 B-MPT patients (pts) are available

Methods:

We conducted a retrospective single-centre observational study to describe outcomes and possible prognostic factors of pts with B-MPT. Data of consecutive patients aged ³18 years old, with a histologically confirmed diagnosis of non-metastatic B-MPT, who underwent surgery from January 2000 to December 2021, were collected. The primary endpoint was the cumulative incidences of any recurrence (local or distant recurrence) defined as the radiological finding of metastatic or local recurrent disease, whichever occurred first (significance at p-value< 0.05).

Results:

131 pts were included. Patient characteristics are reported in Table 1. All patients received a surgery, 5 adjuvant anthracycline-based chemotherapy and 15 radiation therapy.

After a median follow-up of 6.4 years, 36 (28%) pts experienced a disease recurrence: 19 (15%) a distant and 23 (18%) a loco-regional relapse. The cumulative incidence at 5 years of any, local and distant recurrence was of 26% (95% CI, 4-34%), 16% (95% CI, 10-24%) and 10% (95% CI, 5.3-16%), respectively.

At univariate analysis, tumor size ³5 cm was associated with a higher incidence of distant recurrence (p=0.05). Considering only tumors of less than 5 cm in diameter, more distant recurrences were observed in case of at least one negative prognostic factor (i.e., heterogeneous differentiation and/or multifocal diseases) (p=0.067). The type of breast surgery (mastectomy vs. lumpectomy/excision) was not associated with distant (p=0.32) or local (p=0.17) or recurrence, even after controlling local recurrence incidence for the propensity score risk strata (HR: 0.56; 95% CI, 0.24-1.29; p=0.17).

Conclusions:

Natural history of B-MPT is burdened by local and distant recurrences. Pathological features more than the type of wide local excision seem to represent the most significant prognostic factor for recurrences.

Learning Objectives:

upon completion, participant will be able to discuss the best approach to B-MPT
upon completion, participant will be able to offer the best surgical approach to B-MPT
upon completion, participant will be able to discuss in an MDT the best approach to B-MPT