Varying Pathological Features Needed to Determine Prognosis in Myoepithelial Tumors

There is significant clinical, pathological, and outcome heterogeneity in myoepithelial tumors, according to data presented during the 2021 ESMO Congress. Moreover, prognoses for these tumors cannot be determined by a single pathological feature, but rather, several patient and tumor characteristics, and more work is needed to determine biological prognostic factors.

Results from a univariate analysis showed that a prognostic factor for overall survival (OS) is being aged 50 years or older at diagnosis (HR, 4.8; 95% CI, 1.1-22.2). Prognostic factors for local relapse-free survival (RFS) include misdiagnosis before treatment (HR, 3.7; 95% CI, 1.3-10.0), invasion of surrounding tissue (HR, 13.9; 95% CI, 1.6-118.6), multifocal tumors (HR, 5.6; 95% CI, 2.0-15.3), and R2 surgical excision (HR, 12.46; 95% CI, 4.1-38.4). Additionally, prognostic factors for metastatic RFS include invasion of surrounding tissue (HR, 17.4; 95% CI, 2.0-156.0) and high mitotic count (HR, 6.0; 95% CI, 1.6-23.0).

Primary myoepithelial tumors located in the soft tissue or bone are very rare, and little is known about the prognosis or outcomes of patients who have these malignancies. To address this knowledge gap, investigators retrospectively evaluated myoepithelial tumors that had been managed by the French Sarcoma Group from 1990 to 2019.

Overall, a total of 83 patients were treated at 14 centers, and the median follow-up was 58 months. Patients whose tumors were glandular or visceral were excluded from the analysis. Survival curves for patients who underwent surgery were calculated using the Kaplan–Meier method, and a univariate analysis was conducted to identify potential prognostic factors.

Among the patients examined on the study, the median age was 43 years (range, 3-85), and 54.2% were female. Moreover, 8.4% of patients had a previous cancer diagnosis, 8.4% experienced a misdiagnosis prior to receiving treatment, and 95.2% had soft tissue sarcoma.

Regarding location of the tumors, 67.5% of patients had cancer in their limbs, 18.1% in their trunk wall, 8.4% in their head and neck, and 6% in other locations. The median size of the tumors was 50 mm (range, 7-400), 70.0% of patients had a deep tumor (n = 56/80), and 2.4% of tumors invaded surrounding tissue. Furthermore, 9.6% of tumors were multifocal, 4.8% were N1, and 6.0% were M1.

Additionally, 25.6% of patients had EWSR1 rearrangement (n = 10/39), 14.3% had INI1 loss (n = 6/42), 26.9% had high mitotic count (n = 14/52), 26.9% had tumor necrosis (n = 14/52), and 52.8% had moderate or severe atypia (n = 28/53).

In terms of treatments received by patients, 90.4% underwent surgical excision, and 38.6% of these patients had R0 margins, 25.3% had R1 margins, and 6.0% had R2 margins. Of those who received perioperative chemotherapy, 6% received neoadjuvant treatment and 1% received adjuvant treatment. Of those who underwent perioperative radiotherapy, 3.7% received it in the neoadjuvant setting, and 22.0% received treatment in the adjuvant setting.

The median overall survival (OS) in these patients was 298.7 months (95% CI, 147.9–not reached [NR]), and the 2-year OS rate was 90.3% (95% CI, 80.1%-95.3%). The median local RFS was 168.2 months (95% CII, 55.3–NR), and the 2-year local RFS rate was 69.9% (95% CI, 57.9%-79.2%). The median metastatic RFS was 135.9 months (95% CI, 70.4–NR) and the 2-year metastatic RFS rate was 80.7% (95% CI, 69.9%-87.9%).

Reference

1. Cavaillon S, Toulmonde M, Wallet J, et al. Long-term outcomes of primary myoepithelial tumors of soft tissue and bone. Presented at: 2021 ESMO Virtual Congress; September 16-20, 2021; virtual. Abstract 3169.