Rectal cancer with LPLN - T and node characteristics analysis: impact of SIB on oncological outcomes
PO-1311
Abstract
Rectal cancer with LPLN - T and node characteristics analysis: impact of SIB on oncological outcomes
Authors: Elisa Meldolesi1, Roberta Giannini1, Giuditta Chiloiro1, Barbara Corvari1, Stefania Manfrida1, Viola De Luca1, Angela Romano1, Nicola Dinapoli1, Vincenzo Valentini1, Maria Antonietta Gambacorta1
1Fondazione Policlinico Universitario "A.Gemelli" - IRCS, Radioterapia, Roma, Italy
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Purpose or Objective
Involvement of lateral pelvic lymph node (LPLN) in patients with locally advanced rectal cancer (LARC) occurs between 7-15% at the diagnosis, related to a worse prognosis with a 5-year survival rate between 30 to 40%. T and LPLN’s characteristics (e.g. location, size, RT dose) could carry essential information for the definition of the best treatment for this group of patients. The role of a simultaneous integrated radiotherapy boost on LPLN has been investigated.
Material and Methods
We retrospectively collected data from LARC patients with LPLN at the primary staging MRI, treated in our center from March 2003 to December 2020. Patients underwent a neoadjuvant concomitant CTRT treatment on T, mesorectum and pelvic nodes, associated with a fluoride-based chemotherapy +/- oxaliplatin according with the primary stage. Patients were divided in two groups based on whether they received a simultaneous integrated RT boost on the LPLN or not. T and LPLN’s characteristics (e.g. location, size, RT dose) of our population have been investigated. Local control (LC), overall survival (OS), disease free survival (DFS) and metastasis free survival (MFS) were evaluated in the whole group and then compared between the two groups.
Results
A total of 176 patients were evaluated: 82 were included in the RT boost group and 94 in the non-RT boost group. The median follow-up period was 57.8 months (range 52.3 – 63.1). LC, OS, DFS and MFS resulted in 92%, 84.7%, 79.5% and 84.1%, respectively with a statistically significant difference, if considered the boost RT and no boost RT groups (p 0.026, 0.006, 0.042, 0.030) in favor of RT boost group. Initial location either T or LPLN, cranio-caudal T extension and LPLN size did not affected any of the clinical outcomes. Lower cT resulted in having a favorable trend for DFS (p 0.06). Total delivered dose on LPLN resulted the only feature statistically significant in affecting all the clinical outcomes OS, MFS, DFS (p 0.004; 0.027; 0.0076) except for LC where statistical significance wasn’t reached (p 0.06).
Conclusion
Simultaneous integrated RT boost has shown to be beneficial on the survival outcomes (OS; DFS, MFS) in patients with LARC and LPLN. A favorable trend for LC has been observed. Initial T or LPLN’s location, cranio-caudal T extension and LPLN size seemed not to affect any of the clinical outcomes. Lower cT resulted in having a favorable trend for DFS and MFS.