Adjuvant radiotherapy and lymph node status for pancreatic cancer: results of a study from the Surveillance, Epidemiology, and End Results (SEER) Registry Data.

OBJECTIVES: This study explores the relationship of lymph node ratio (LNR) and radiotherapy (RT) to overall survival (OS) for patients with resected pancreatic cancer. The impact of adjuvant RT, number of lymph nodes (LN) resected, positive LN resected, and disease extension was also evaluated.
METHODS: The SEER database from 1998 to 2006 was reviewed, and 3314 patients with nonmetastatic carcinoma of the pancreas, surgical resection, examination of the regional LN, and a survival of >2 months were identified. Of these, 1597 patients received RT. Cox proportional hazards regression models and the logrank test were used to determine whether specific variables were related to OS.
RESULTS: Median OS for patients having surgery alone was 14 months (1-y survival 58.1%, 2-y survival 33.6%) and for patients having adjuvant RT was 19 months (1-y survival 73.5%, 2-y survival 41.4%), P<0.001. For patients with LNR of 0%, OS was better compared with patients with any LN involvement, regardless of treatment group. Multivariable analysis found OS significantly related to LNR, total LN resected, positive resected LN, year of diagnosis, and regional extent of disease in patients without adjuvant RT. In patients who received adjuvant RT, OS significance was only persistent for LNR, the total LN resected, and positive resected LN.
CONCLUSIONS: A higher LNR was indicative of worse OS in all patients. A strong association with improvement in OS was seen in patients having received adjuvant RT.