Long-term oncologic outcomes in elderly patients with localized anal cancer.

e15502 Background: Localized anal cancer (LAC) is a rare malignancy, with limited data on treatment tolerance and outcomes in elderly patients (pts). We conducted a real-world data analysis to evaluate the safety and efficacy of standard treatments with curative intent in this population. Methods: This retrospective cohort evaluates the Sao Paulo Cancer Institute electronic medical records database between 2017-2024. The primary endpoint was overall survival (OS), and secondary endpoints were disease-free survival (DFS) and safety in pts ≥ 65y with LAC. Results: Among the 551 pts database, 192 (34.8%) had ≥65 years(y), and 178 were included in the study. Age distribution was 46.8% in 65–75y and 53.1% >75y. Most patients were female (75.8%), had squamous cell carcinoma (95.9%), and had an ECOG performance status of 0–1 (81.2%), with 7.9% being HIV-positive. 89.9% (n=160) had LAC, 60.7% stage III at diagnosis. 155 (96.9%) received curative treatment, with concurrent CRT in 85%. CRT regimens included fluoropyrimidine (FP) plus cisplatin (CDDP) in 44.8%, FP plus mitomycin (MMC) in 29%, and FP in 28.7%. Of 105 pts with 6-month (m) radiologic evaluations, 60% achieved complete response. At a median follow-up of 49 months, 39 pts experienced recurrence, and 51 died, with anal cancer-related deaths in 70.1%. Grade ≥3 adverse events (AE) occurred in 61.1%. Treatment discontinuation due to AE occurred in 27%, hospitalization in 24.3%, and treatment-related death in 4.8%. Patients receiving FP+MMC had higher rates of treatment discontinuation due to toxicity (43.1% vs. 13.6%, P=0.001) and febrile neutropenia (10.4% vs. 1.8%, P=0.021) compared to those receiving FP+CDDP. The 5y OS was significantly higher in pts ≤ 75y (table). Conclusions: A high proportion of anal cancer cases occur in elderly pts. In this cohort, we found considerable rates of toxicity and treatment-related mortality, with safety concerns particularly pronounced in the FP+MMC CRT group. Poor 5y DFS and OS were observed in patients with >75 years. Oncologic outcomes. 5-year DFS HR (95%CI) 5-year OS HR (95%CI) Stage I 80% ref 80% ref Stage II 71.9% 2.35 (0.41-17.92) 82.1% 1.48 (0.18-11.77) Stage III 51.3% 3.49 (0.48-25.42) 58.8% 2.94 (0.40-21.50) RT alone 57.1% ref 57.1% ref CRT with single agent 55% 0.96 (0.31-2.97) 50.7% 0.84 (0.28-2.52) CRT with FP+CDDP 59.7% 0.74 (0.28-1.94) 70.9% 0.47 (0.17-1.27) CRT with FP+MMC 58.9% 0.72 (0.27-1.92) 72.6% 0.39 (0.14-1.07) 65-75y 70% ref 79.9% ref >75y 46.3% 2.52 (1.48-4.28) 52.3% 3.31 (1.78-6.12)