MRI assessment of surrounding tissues in soft-tissue sarcoma during neoadjuvant chemotherapy can help predicting response and prognosis

Objectives: To determine if changes in surrounding tissues of soft-tissue sarcomas (STS) evaluated by MRI during neoadjuvant chemotherapy (NAC) are associated with the histological response and satellite tumorous cells beyond the pseudocapsule on surgical specimen, disease-free survival (DFS) and overall survival (OS). Methods: Fifty-seven adult patients with locally advanced high-grade STS of extremities and trunk wall were included in this single-centre retrospective study. All were uniformly treated by 5-6 cycles of anthracycline-based NAC, curative surgery and adjuvant radiotherapy and had available MRI with a gadolinium-chelates administration at baseline and after 2 cycles. Thirty-seven patients also had a pre-operative MRI. Two senior radiologists evaluated MRI growth pattern, oedema, contrast-enhanced oedema, aponeurotic enhancement, and their qualitative changes during NAC. An expert pathologist reviewed all surgical specimens. A good histological response was defined as < 10% viable cells. Associations with pathological findings were estimated with Fisher and Chi-square tests and multivariate analysis with binary logistic regression. Survival analyses included log-rank tests. Results: Forty-two patients had poor responses and 25 had satellite tumorous cells on surgical specimen. Changes in surrounding oedema and in contrast-enhanced oedema were associated with responses (p = 0.008 and 0.011, respectively). Diffuse infiltrative growth pattern (IGP) on baseline MRI, changes in margin definition and in contrast-enhanced oedema at early evaluation were associated with satellite tumorous cells (p = 0.039, 0.011 and 0.009, respectively). Diffuse IGP on baseline MRI and stable or increased oedema during treatment were predictors of DFS (p = 0.009 and 0.040, respectively). Conclusion: Surrounding tissues of STS during NAC should be carefully evaluated as they may steer treatment efficacy and patient prognosis.