Abstract 409P
Background
Mitomycin has been increasingly replaced by cisplatin during chemoradiation for patients (pts) with localized SCCA in countries where mitomycin is not available. Real-world data on the outcomes from the ACT-II regimen (cisplatin + fluoropyrimidine) are warranted.
Methods
The GTG-LACOG 1318 study is a Brazilian multicenter retrospective cohort of SCCA pts. Here we evaluated the effects of treatment regimen (Nigro vs ACT-II regimen) on clinical complete response (cCR), disease-free survival (DFS) and colostomy-free survival (CFS) of stage I-III pts, using logistic and Cox regression analyses. Independent variables were sex, age, comorbidities, treatment regimen and clinical stage.
Results
From Apr/2010 to Aug/2020, 148 pts underwent definitive CRT: median age was 59 years, 123 (83.1%) was female, 77 (52.3%) had stage I/II and 70 (47.6%) stage III disease. Radiotherapy (RT) technique was IMRT for 103 (69.6%), 3D conventional RT for 37 (25%) and 2D RT for 8 (5.4%) pts. Treatment was completed as planned by 132 (89.2%) of pts. ACT-II was used in 75 (51.0%) and Nigro in 68 (46.2%) of cases – 4 pts received only capecitabine with RT. At 6 months (m), 47 of 75 (62.7%) and 55 of 68 (80.9%) pts achieved cCR with ACT-II vs Nigro regimen (p=0.08), respectively. 24 of 75 (32.0%) and 15 of 68 (22.1%) pts needed a colostomy with ACT-II vs Nigro regimen (p = 0.19). After a median follow up of 40 m, 3-year OS, DFS and colostomy-free survival were 87.2%, 77.0% and 74.6%, respectively. Stage (I/II vs. III) was associated with higher likelihood of achieving cCR (OR 2.11, 95% CI 1.01 – 4.42, p = 0.045), longer DFS (HR 0.17 95% CI 0.07 – 0.43, p < 0.001) and CFS (HR 0.21, 95% 0.09 - 0.46, p < 0.001) in multivariable models adjusted for treatment regimen and sex. Nigro was associated with a higher likelihood of achieving cCR after controlling for stage and sex (OR 2.76, 95% CI 1.24 – 6.13 p = 0.012), but treatment regimen was not associated with a longer DFS or CFS.
Conclusions
The ACT-II regimen for pts with SCCA seems to offer similar DFS and CFS but inferior cCR at 6m post chemoradiation when compared to the Nigro regimen. We will further investigate whether cisplatin leads to longer time to achieve cCR, beyond 6 m post treatment.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Brazilian Gastrointestinal Tumors Group (GTG) and LACOG.
Disclosure
All authors have declared no conflicts of interest.