Stanford University School of Medicine Stanford, CA
S. S. Butler1, T. Niedermayr2, and E. A. Kidd2; 1Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA, 2Department of Radiation Oncology, Stanford University, Stanford, CA
Purpose/Objective(s): Recent prospective data for cervical cancer showed that treatment intensification with the addition of induction chemotherapy or concurrent/adjuvant pembrolizumab improved progression free survival. To elucidate which populations may particularly benefit from treatment escalation, we analyzed outcomes across various risk features of patients undergoing standard of care definitive treatment. Materials/
Methods: This single institution retrospective cohort study included 227 patients who completed definitive external beam radiotherapy (EBRT) and brachytherapy (BT) from December 2010 to July 2023. Competing risks analysis calculated multivariable adjusted hazard ratios (aHRs) and cumulative incidence of local recurrence (LR) and any recurrence (AR), with death as a competing event. Results: Out of 227 patients, 28 (12%) had LR, 82 (36%) had AR, and median follow-up was 37 months (IQR, 16-61 months); 48% had EBRT at outside facility, 3.5% had RT alone (no concurrent chemo). Baseline features were as follows for FIGO 2018 stage (I, 4.9%; II, 20%; III, 56%; IV, 19%), histology (squamous cell [SCC], 76%; adenocarcinoma [AC], 15%; other/high-risk, 9.2%), age (median 52 years), race (white, 41%), N1-2 (67%), and M1 disease (4.8%). 3-year LR was higher with FIGO stage IV vs I-III disease (26.5% vs 10.6%; aHR 3.69, P=0.002), high-risk histology vs SCC/AC (31.0% vs 11.8%; aHR 2.95, P=0.018), minority vs other race (28.6% vs 12.6%; aHR 4.16, P=0.018), total care time >11 vs =11 weeks (TCT; time from biopsy to RT completion) (16.4% vs 4.8%; aHR 5.54, P=0.044), and outside EBRT (17.6% vs 9.9%, P=0.029 [log-rank]; aHR 2.29, P=0.079). There was no difference in 3-year LR by package time =50 vs <50 days (PT; time from treatment start to end) (12.5% vs 13.4%, P=0.65 [log-rank]; aHR 0.47, P=0.10). Patients with EBRT and BT at different sites (vs single site) had longer median TCT (116 vs 91 days, P<0.001) and PT (56 vs 48 days, P<0.001). Those with TCT >11 (vs =11) weeks had more outside EBRT (57% vs 15%, P<0.001), longer median PT (51 vs 48 days, P<0.001), and smaller mean tumor size (5.1 vs 5.9 cm, P=0.01); Baseline characteristics were otherwise balanced. No interactions between TCT and other covariates were significant on subgroup analyses. 3-year AR was higher with FIGO stage IV vs I-III disease (57.9% vs 30.2%; aHR 1.98, P=0.007), bulky nodes (>2.5 cm) or M1 disease vs non-bulky/N0M0 (63.9% vs 33.3%; aHR 2.13, P=0.027), and high-risk histology vs SCC/AC (67.6% vs 32.1%, P=0.045 [log-rank]; aHR 1.71, P=0.084). Conclusion: Outcomes appeared worse with longer TCT (>11 weeks), high-risk histology, minority race, FIGO stage IV, M1 disease, and bulky nodes. Non-consolidated care (EBRT/BT at different sites) had prolonged TCT and may be associated with worse LR. Future research is needed to determine whether patients with these high-risk pretreatment features may preferentially benefit from treatment escalation paradigms.
