Abstract 435P
Background
Mitomycin unavailability in many countries has led to an increased use of cisplatin for patients (pts) with localized SCCA. However, real-world data on the outcomes with cisplatin are warranted.
Methods
The GTG-LACOG 1318 study is a multicenter retrospective cohort of SCCA pts. We present the final results, focusing on the impact of treatment regimen on clinical complete response (cCR), colostomy-free survival (CFS) and disease-free survival (DFS) of pts with stage I-III disease, using multivariate adjusted logistic and Cox regression analyses.
Results
From Feb/2006 to Feb/2022 181 pts underwent definitive CRT: median age was 61 years, 147 (81.2%) were female, 93 (52.2%) had stage I/II and 85 (48.8%) stage III disease. Radiotherapy (RT) technique was IMRT for 111 (62.0%) pts and CRT was completed by 157 (87.7%) pts. Mitomycin + FU, cisplatin + FU and capecitabine alone were used by 80 (44.2%), 94 (51.9%) and 7 (3.9%) pts, respectively. At 6 months (m), 63 (80.9%) and 61 (62.7%) pts had achieved cCR with mitomycin vs. cisplatin (p=0.02). At a median follow up of 43.3 m, 3-yr CFS, DFS and OS were 74.8%, 77.9% and 89.7%, respectively. Stage (I/II vs. III) was associated with higher likelihood of achieving cCR (OR 3.33, 95% CI 1.55 – 7.16, p = 0.002), longer DFS (HR 0.22, 95% CI 0.10 – 0.48, p < 0.001) and longer CFS (HR 0.33, 95% 0.17 - 0.65, p = 0.001) adjusted for treatment regimen and sex. Use of mitomycin vs. cisplatin was associated with a higher likelihood of achieving cCR (OR 2.68, 95% CI 1.24 – 5.81 p = 0.012), and a shorter time to clinical response (3.4 vs 6.5 m; HR 1.95, 95% CI 1.36 – 2.79; p < 0.001) but was not associated with a longer DFS or CFS or colostomy rates (22.5% vs 29.7%; p = 0.27). Table: 435P
Demographic characteristics
| Age (years, median, range) | 61 (32-85) |
| Sex (women, %) | 83.1% |
| ECOG (%) | |
| 0 | 54.7% |
| 1 | 44.7% |
| 2 | 0.6% |
| Stage (%)* | |
| I | 10.6% |
| IIA | 33.7% |
| IIB | 7.8% |
| IIIA | 19.6% |
| IIIB | 9.5% |
| IIIC | 18.5% |
*missing = 3
Conclusions
Substitution of mitomycin for cisplatin seems to offer similar DFS and CFS but was associated with inferior cCR rates after CRT and longer time to cCR in the real world.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
Latin American Cooperative Oncology Group (LACOG).
Funding
Brazilian Gastrointestinal Tumors Group (GTG) and Latin American Cooperative Oncology Group (LACOG).
Disclosure
All authors have declared no conflicts of interest.