Tolerability and outcomes after neoadjuvant and definitive radiation of elderly patients with localized pancreatic cancer.

664 Background: Multimodal therapy for pancreatic cancer (PC) may be challenging in older adults with comorbidities or limited performance status (PS). Methods: This is a retrospective review of patients (pts) age 70 and older with localized PC treated with neoadjuvant or definitive radiation (RT) at the Massachusetts General Hospital from 2016-2024. Kaplan-Meier method was used to estimate progression-free survival (PFS) and overall survival (OS) calculated from RT start. The Cox model was used to assess predictors of survival: age (>75 vs ≤75), ECOG PS (1+ vs 0), NCCN Stage (resectable vs not), ypT (2+ vs 0/1) and N (1 vs 0), and resection (yes vs no). Results: 366 pts met inclusion criteria with a median follow-up of 13 mo (range 0.2-102.2). Median age was 75 (range 70-95). 339 pts (93%) were deemed medically fit for surgery of whom 153 had resectable, 58 had borderline, and 128 had locally advanced disease. 317 of the 339 pts (94%) received induction chemotherapy (INCT), including: FOLFIRINOX (n=249), gemcitabine/nab-paclitaxel (n=61), and gemcitabine (n=29). 27 pts were deemed medically inoperable, of whom 11 were treated with INCT and RT and 16 with RT alone. RT regimens included: 50.4-58.8 Gy/28 fractions (fx) (n=223), 40 Gy/10 fx (n=2), 30 Gy/10 fx (n=52), 33-40 Gy/5 fx (n=28), or other (n=61). 3 discontinued RT due to toxicity (n=2) or progression (n=1). Of the 339 pts deemed medically fit, 206 (61%) had resection. The R0 resection rate was 86%. Median OS of the entire, medically operable and inoperable cohorts was 18.9 (95% CI 16.2-22.7), 20.3 (95% CI 17-25.4), and 10.1 (95% CI 7.5-17.1) mo. Median PFS of the entire, medically operable and inoperable cohorts was 9.6 (95% CI 8.3-11.5), 10.1 (95% CI 8.8-12.2), and 6.9 (95% CI 4.8-9.1) mo. Table 1 shows PFS and OS by NCCN categories. Univariate predictors of PFS and OS included age (HR 1.31 (p=0.029); HR 1.46 (p