Paradoxical Response to Neoadjuvant Therapy in Undifferentiated Pleomorphic Sarcoma: Increased Tumor Size on MRI Associated with Favorable Pathology

• Published in: Cancers Vol. 17; no. 5; p. 830
• Main Authors: Goreish, Mariam H., Gennaro, Nicolò, Perronne, Laetitia, Durak, Gorkem, Borhani, Amir A., Savas, Hatice, Kelahan, Linda, Avery, Ryan, Subedi, Kamal, Agirlar Trabzonlu, Tugce, Bagci, Ulas, Turkbey, Baris, Bakas, Spyridon, Sachdev, Sean, Sumagin, Ronen, Alexiev, Borislav A., Hermida de Viveiros, Pedro, Pollack, Seth M., Velichko, Yuri S.
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 01.03.2025; MDPI
• Subjects: Adjuvant treatment; Antimitotic agents; Antineoplastic agents; Biopsy; Cancer; Care and treatment; Delivery services; Histopathology; Magnetic resonance imaging; Neoadjuvant therapy; Pathology; Patients; Radiation therapy; Sarcoma; Survival analysis; Tumors; United States; Illinois; neoadjuvant chemoradiotherapy; RECIST; pathology; sarcoma; MRI
• ISSN: 2072-6694; 2072-6694
• DOI: 10.3390/cancers17050830

Background/Objectives: To correlate size changes in undifferentiated pleomorphic sarcoma (UPS) on magnetic resonance imaging (MRI) after neoadjuvant chemoradiation therapy (nCRT) with pathological response, risk of local recurrence, and therapeutic regimens. Methods: This retrospective study analyzed clinical, pathological, and imaging data from 39 biopsy-proven UPS subjects. Four readers measured the tumor dimensions before and after nCRT, including two perpendicular axial diameters and the longest coronal/sagittal diameter. Three cross-sectional areas and bounding volume were also calculated. Responders (pR) were defined as having ≤10% viable cells and non-responders (pNR) as having more. Inter-reader agreement was evaluated using Kendall’s concordance coefficient. Changes in tumor size were compared between pR and pNR using one-way ANOVA and Tukey’s HSD test for multiple comparisons of means. Results: pR showed a greater increase in size across all measurements compared to pNR. For the longest axial diameter, the mean increase was 30% ± 35% for pR and 14% ± 31% for pNR, with a mean difference (pR-pNR) of 16% (95% CI: 6–27%, p = 0.003). In tumors treated with radiotherapy alone, pR exhibited larger size increases in all dimensions compared to pNR. In contrast, in the chemoradiation group, pR showed a slight increase, while pNR generally shrank, although these differences did not reach statistical significance. Notably, pNR with local recurrence exhibited a reduction in all tumor dimensions compared to pNR without local recurrence. Conclusions: This exploratory study suggests that tumor size changes may predict pathological response and local recurrence after nCRT in UPS; however, the small sample size limits the generalizability of these findings.