Comparative efficacy of postoperative adjuvant chemoradiotherapy versus no chemoradiotherapy in the treatment of pancreatic adenocarcinoma

BACKGROUND: The benefit of adjuvant chemoradiotherapy (CRT) for pancreatic adenocarcinoma (PAAD) is debated. This study aimed to elucidate the impact of adjuvant CRT on survival outcomes. METHODS: We searched major medical databases for clinical and retrospective studies comparing postoperative CRT vs. no CRT in PAAD. Data were synthesized using RevMan 5.4 and Stata 17.0 software. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated for overall survival (OS), local recurrence, and distant metastasis. RESULTS: Our analysis included 19 studies involving 4,581 patients. Adjuvant CRT was associated with a significant improvement in 2-year OS compared to no CRT (OR = 0.63, 95% CI: 0.53-0.76, P < 0.001). This benefit was consistent in subgroup analyses compared to chemotherapy alone (OR = 0.54, P = 0.0003) and the observation group (OR = 0.61, P < 0.001). The 5-year OS analysis showed a non-significant trend favoring CRT (OR = 0.66, 95% CI: 0.43-1.02, P = 0.06). In subgroup analyses, CRT was associated with a significant survival benefit compared with observation alone (OR = 0.67, 95% CI: 0.47-0.97, P = 0.03), but not compared with chemotherapy alone (OR = 0.57, 95% CI: 0.06-5.46, P = 0.62). Notably, patients with high-risk features, including lymph node-positive (2-year OS: OR = 0.47, P < 0.001; 5-year OS: OR = 0.53, P < 0.001) and margin-positive disease (2-year OS: OR = 0.45, P < 0.001), derived substantial survival benefits from CRT. Furthermore, CRT was significantly associated with reduced local recurrence rates (OR = 0.27, P = 0.008) but did not affect the incidence of distant metastasis (OR = 1.11, P = 0.72). CONCLUSIONS: This study shows that adjuvant CRT significantly improves 2-year OS and local tumor control in resected PAAD, especially for patients with lymph node metastasis. However, its effect on long-term (5-year) survival is limited, and it was not associated with distant metastasis. These findings support the selective use of adjuvant CRT for local control in high-risk patient subgroups, such as those with positive lymph nodes or positive surgical margins. Further research is needed to prospectively validate these findings and identify patients most likely to benefit.