Lymph node involvement influences prognosis in resectable non-metastatic solid pseudopapillary tumors of the pancreas: a SEER-based population study

Solid Pseudopapillary Tumors (SPT) of the pancreas are rare neoplasms with an often indolent biological behavior. Given the rarity of this pathology, studies based on large population registries are fundamental to delineate patient profiles and survival. This study aims to analyze characteristics and survival in patients with resectable non-metastatic pancreatic SPTs utilizing a large population database. This study analyzed data from SEER database, focusing on patients with resected non-metastatic SPT of the pancreas. We excluded patients who did not undergo surgery, with inadequate lymphadenectomy, or with metastatic disease. Patients and tumors characteristics were extracted. Univariate and multivariate Cox regression analyses were performed to identify factors influencing prognosis. Kaplan-Meier curves were used to compare survival across subgroups. A contour plot and restricted cubic spline were calculated to assess the relationship between variables and hazard. The study included 293 patients, predominantly female (84.6%) with a median age of 20-40 years (44.4%). The overall 5-year OS was 96.2%. Kaplan-Meier analysis showed that patients with positive lymph-nodes had a markedly worse prognosis, as did patients with older age. Survival was also influenced by tumor location, with head or body tumors showing lower survival than tail tumors after approximately 100 months. In multivariate Cox regression, age ( p = 0.004), location ( p = 0.006), positive lymph nodes ( p < 0.001), and chemotherapy ( p < 0.001) were significant predictors. The contour plot and restricted cubic spline confirmed that predicted hazard increased with both age and the number of positive lymph nodes. This large population-based study confirms that resectable, non-metastatic SPT generally have a favorable prognosis. However, factors such as advanced age, tumor location, and, in particular, lymph node involvement are associated with a worse prognosis. These observations are crucial for risk stratification and treatment planning in this rare patient population.