Tumour localization and oncological outcomes in nonuterine leiomyosarcoma of the abdomen and pelvis.

BACKGROUND

Leiomyosarcoma is an aggressive soft tissue sarcoma. While some evidence supports different biological behaviour between uterine and non-uterine LMS (NULMS), outcome data for NULMS according to tumour localization are limited. We evaluated the impact of tumour localization on oncological outcomes in abdominal and pelvic NULMS.

METHODS

Patients with abdominal or pelvic NULMS diagnosed between 2005 and 2022 were identified from an institutional sarcoma database. Non-operated patients, uterine LMS, and cases with incomplete data were excluded. Patients were grouped by primary tumour location: visceral, retroperitoneal, or pelvic.

RESULTS

A total of 120 patients (median age 61 years) were included: 47 retroperitoneal, 35 visceral, and 38 pelvic tumours. Median tumour size was 8 cm, with larger tumours in the retroperitoneal group (10.0 vs. 6.5 cm, p = 0.002). Complete resection was achieved in 67.5% of patients and was less common in retroperitoneal and pelvic tumours. Survival analyses of 104 patients (median follow-up 83 months) showed a median OS of 111 months, with 5- and 10-year OS rates of 65% and 46%. Median DFS was 65 months. Recurrence occurred in 39% of patients, mainly as distant metastases. Retroperitoneal LMS and especially suprahepatic IVC involvement were associated with poor OS. On multivariable analysis, retroperitoneal location, R1 resection, and high tumour grade independently predicted inferior OS.

CONCLUSIONS

Retroperitoneal LMS demonstrates significantly poorer survival than visceral LMS, while pelvic LMS shows intermediate outcomes. Suprahepatic IVC involvement confers a poor prognosis, underscoring the importance of treatment decision-making by a multidisciplinary team.