The rate of soft-tissue sarcoma has nearly doubled over the past two decades, and up to 50% of patients with tissue sarcoma develop lung metastasis. A single-center study of 539 patients who had treatment for soft-tissue sarcoma has revealed disease and treatment characteristics that may aid patient selection and help predict overall and disease-free survival after diagnosis and treatment.
“Histologic subtype and size of the primary tumor were significantly associated with overall survival,” said lead author Neel P. Chudgar, MD, and his coauthors in the July issue of the Journal of Thoracic and Cardiovascular Surgery (2017;154:319-30).
“Patients who underwent pulmonary metastasectomy [PM] for pleomorphic sarcoma/malignant fibrous histocytoma had the shortest median overall survival (23.6 months), whereas those who underwent PM for leiomyosarcoma had a median overall survival of 42 months,” he said.
The study subjects had pulmonary metastasectomies at Memorial Sloan Kettering Cancer Center, New York, during September 1991–June 2014. The median overall survival was 33.2 months, and median disease-free survival was 6.8 months for the entire cohort.
Among the disease characteristics associated with a lower hazard ratio of death shown by multivariable analyses were leiomyosarcoma histologic subtype (HR, 0.57), primary tumor size of 10 cm or less (HR, 1.00 vs. HR, 1.37 for those greater than 10 cm), increasing time from primary tumor resection to development of metastases (HR, 0.4 at less than 24 months vs. 1.0 at less than 6 months), solitary lung metastasis (HR, 1.0 vs. 1.8 for one year or more), and minimally invasive resection (HR, 0.71), all of which were statistically significant differences. Disease-free interval of more than one year and one pulmonary metastasis were significantly associated with lower hazard of disease recurrence.
Of patients, 70% had pulmonary metastasectomy as their primary treatment. The remainder had induction chemotherapy. In addition, 71% had open procedures over the 23-year study period, but minimally invasive operations became more common with time, increasing more than fourfold from the first half of the study period, vs. the last. They accounted for more than half of all procedures in the last five years of the study.
With regard to tumor type, fibrosarcoma was associated with longest median overall survival (65.2 months). Dr. Chudgar and his colleagues noted that 43% of these patients had low-grade primary tumors. Patients with low-grade tumors of all types had a median overall survival of 71.8 months, vs. 30.8 months for those with high-grade tumors.
“Our results indicate that therapeutic-intent pulmonary metastasectomy for soft-tissue sarcoma can be associated with prolonged survival,” Dr. Chudgar and his coauthors said. “The median survivals in our study are comparable with those in previous studies.” However, their analysis went beyond previous studies because they identified positive prognostic factors.
Dr. Chudgar and his coauthors acknowledge that various studies have drawn conflicting conclusions about the validity of histologic subtype as a prognostic factor, but their study differs from previous studies because it is a single-center cohort, “which increases the power to potentially identify significant differences, and we focused on soft-tissue sarcoma exclusively to enhance the homogeneity of the study population.”
Nonetheless, the researchers noted some limitations of their study, namely their collective analysis of the various soft-tissue sarcoma subtypes and the lack of a control group. Soft tissue sarcoma, because of its heterogeneous nature, challenges the adoption of precision medicine for this cancer type, but, until clinicians better understand the underlying mechanism of metastasis in these tumor types, Dr. Chudgar and his coauthors said, pulmonary metastasectomy “remains the best available treatment for soft tissue sarcoma pulmonary metastases.”
Dr. Chudgar and his coauthors had no financial relationships to disclose.