(P 247) PROGNOSTIC VALUE OF MITOTIC COUNT IN NON-UTERINE LEIOMYOSARCOMAS: A MONOCENTRIC RETROSPECTIVE STUDY.

Author(s)

Maria Susanna Grimaudo, MD (she/her/hers)

Oncology Resident
Medical Oncology and Hematology Unit, Humanitas Clinical and Research Center, IRCCS, Rozzano, Milan, 20089, Italy
Rozzano, Lombardia, Italy

Co-Author(s)

Alice Laffi, MD

Medical Oncologist
Medical Oncology and Hematology Unit, Humanitas Clinical and Research Center, IRCCS, Rozzano, 20089, Italy
Rozzano, Lombardia, Italy
LR

Lorenzo Salvatore Renne, MD

Pathologist
Humanitas Research Hospital
Rozzano, Lombardia, Italy
LG

Laura Giordano, MSc

Humanitas Clinical and Research Center, IRCCS, Rozzano, 20089, Italy
Rozzano, Lombardia, Italy
PC

Piergiuseppe Colombo, MD

Pathologist
Pathology Unit, Humanitas Clinical and Research Center, IRCCS, Rozzano, 20089, Italy
Rozzano, Lombardia, Italy
FD

Federico D'Orazio, MD

Department of Radiology, Humanitas Clinical and Research Center, IRCCS, Rozzano, 20089, Italy.
Rozzano, Lombardia, Italy
VQ

Vittorio Quagliuolo, PhD

Department of Biomedical Sciences, Humanitas University, Via Rita Levi Montalcini 4, 20090 Pieve Emanuele - Milan, Italy. Sarcoma, Melanoma and Rare Tumors Surgery Unit, Humanitas Clinical and Research Center, IRCCS, Rozzano, 20089, Italy.
Rozzano, Lombardia, Italy
Federico Sicoli, MD (he/him/his)

Surgeon
Sarcoma Surgery Unit, Humanitas Clinical and Research Center, IRCCS, Rozzano, 20089, Italy
Rozzano, Lombardia, Italy
Armando Santoro, MD

Director
Medical Oncology and Hematology Unit, Humanitas Clinical and Research Center, IRCCS, Rozzano, 20089, Italy. Department of Biomedical Sciences, Humanitas University, Via Rita Levi Montalcini 4, 20090 Pieve Emanuele - Milan, Italy.
Rozzano, Lombardia, Italy
Alexia Francesca Bertuzzi, MD (she/her/hers)

medical oncology consultant
Medical Oncology and Hematology Unit, Humanitas Clinical and Research Center, IRCCS, Rozzano, 20089, Italy
Rozzano, Lombardia, Italy

Objective: To assess the prognostic role of mitotic count of the primary tumor in non-uterine leiomyosarcomas (leio).

Methods: We retrospectively analyzed the data of all patients with a histologic diagnosis of non-uterine leio treated in our Hospital from January 2000 to September 2020. The study was planned to include patients with surgery sample whose pathology report expressed mitotic count in number. We excluded patients with only a biopsy, not representative of the whole disease, and those with pretreated disease, potentially altered by the treatment-induced modifications. Clinical and pathological data have been gathered in an electronic Data Base.

Results: We identified 46 eligible cases. For these patients, the median follow-up was 52 months (range 2 - 252). The mean age at diagnosis was 56 years old (range 24 – 81). According to the Eight Edition of the American Joint Committee on Cancer (AJCC) Cancer Staging system, 11% (5/46) of patients had stage I disease, 28% (13/46) stage II, 37% (17/46) stage III and 15% (7/46) stage IV; in 9% (4/46) of patients the stage at diagnosis was unknown. According to the Fédération Nationale des Centres de Lutte le Cancer (FNCLCC) grading (G) system, 22% (10/46) of leio were classified as G1, 28% (13/46) as G2, 48% (22/46) as G3 and in 2% (1/46) the grade was unknown. The dimension of the primary was ≤ 5 cm in 35% (16/46) of the cases, > 5 cm in 52% (24/46) and it was unknown in 13% (6/46). Among the study patients, 22% (10/46) received adjuvant radiotherapy, 20% (9/46) received adjuvant chemotherapy and 35% (16/46) received ≥1 line of systemic treatment for metastatic disease. The median mitotic count was 12 mitoses per 10 high-power fields (HPF) (range 1 – 53).
In the study population, 3 years progression-free survival (PFS) was 41% (median PFS = 16 months), and 3 years overall survival (OS) was 81% (median OS = not reached). Considering the mitotic count as a continuous variable, the PFS was significantly lower for patients with progressively higher mitotic count (Hazard Ratio – HR – per mitotic unit: 1.031, CI 1.004 – 1.058, p 0.0238). The OS was significantly worse for patients with progressively higher mitotic count which resulted in a statistical increase of risk of death (HR per mitotic unit of 1.044, CI 1.005 – 1.085, p 0.0267).

Conclusion: Our findings suggest a prognostic role of the mitotic count on the PFS and OS in non-uterine leio. As already reported in uterine leio, the mitotic count seems to have a significant impact on the prognosis, regardless of necrosis and differentiation. Further prospective studies are needed.