Comparing Oncologic Outcomes and Toxicity for Combined Modality Therapy vs. Carbon-Ion Radiotherapy for Previously Irradiated Locally Recurrent Rectal Cancer.

No standard treatment paradigm exists for previously irradiated locally recurrent rectal cancer (PILRRC). Carbon-ion radiotherapy (CIRT) may improve oncologic outcomes and reduce toxicity compared with combined modality therapy (CMT). Eighty-five patients treated at Institution A with CIRT alone (70.4 Gy/16 fx) and eighty-six at Institution B with CMT (30 Gy/15 fx chemoradiation, resection, intraoperative electron radiotherapy (IOERT)) between 2006 and 2019 were retrospectively compared. Overall survival (OS), pelvic re-recurrence (PR), distant metastasis (DM), or any disease progression (DP) were analyzed with the Kaplan-Meier model, with outcomes compared using the Cox proportional hazards model. Acute and late toxicities were compared, as was the 2-year cost. The median time to follow-up or death was 6.5 years. Median OS in the CIRT and CMT cohorts were 4.5 and 2.6 years, respectively (p ≤ 0.01). No difference was seen in the cumulative incidence of PR (p = 0.17), DM (p = 0.39), or DP (p = 0.19). Lower acute grade ≥ 2 skin and GI/GU toxicity and lower late grade ≥ 2 GU toxicities were associated with CIRT. Higher 2-year cumulative costs were associated with CMT. Oncologic outcomes were similar for patients treated with CIRT or CMT, although patient morbidity and cost were lower with CIRT, and CIRT was associated with longer OS. Prospective comparative studies are needed.

Determinants of tumor treating field usage in patients with primary glioblastoma: A single institutional experience.

Background: Determinates of tumor treating fields (TTFields) usage in patients receiving combined modality therapy for primary IDH wild-type glioblastoma are currently unknown. Methods: Ninety-one patients underwent maximal debulking surgical resection, completed external beam radiotherapy with concurrent Temozolomide (TMZ), and initiated adjuvant TMZ with or without TTFields. We performed a retrospective analysis of patient, tumor, and treatment-related factors that affected TTFields usage. Results: We identified three TTFields usage subgroups: 32 patients that declined TTFields, 40 patients that started, but had monthly compliance of less than 75% or used it for less than 2 months, and 19 patients who used TTFields for 2 or more months and maintained average monthly compliance greater than 75%. With 26.5 months median follow-up for surviving patients, the 1- and 3-year actuarial overall survival for all patients was 80% and 18%, respectively. On multivariate analysis TTFields use (P = .03), extent of surgical resection (P = 0.02), and MGMT methylation status (P = .01) were significantly associated with overall survival. TTFields usage was explored as a continuous variable and higher average usage was associated with longer overall survival (P = .03). There was no relationship between patient, tumor, or treatment-related factors and a patient's decision to use TTFields. Conclusions: No subgroup of patients was more or less likely to initiate TTFields therapy and no subgroup was more or less likely to use TTFields as prescribed. The degree of TTFields compliance may be associated with improved survival independent of other factors.