347 Background: 9,704 was the first phase 3 pancreatic cancer trial to validate the prognostic value of postresection CA19-9 for overall survival (OS), with values > 90/180 associated with worse OS. All pts received adjuvant gemcitabine or 5-FU and chemo-radiotherapy (RT). This analysis evaluates patterns of disease failure. Methods: SMS was negative, positive, or unknown. CA19-9 was analyzed at cut points 90, 180 and continuously. LRF and DF were estimated by cumulative incidence and Gray’s test compared. Cox hazard models were used for multivariate analyses (MVA) and included treatment, tumor site, size and nodal status. To adjust for multiple comparisons a p-value < 0.01 is statistically significant and 0.01 to < 0.05 a trend. Results: 538 pts accrued, with 451 eligible and analyzable for SMS and 385 for CA19-9. For CA19-9, 132 (34%) were Lewis Antigen negative (no CA19-9 expression), 200 (52%) < 90 and 220 (57%) < 180. 188 (42%) had negative margins, 152 (34%) positive and 111 (25%) unknown (i.e., no margin comment in path report; shown to have outcomes similar to negative margin pts). Pts with CA19-9 ≥ 180 were more likely to have tumors ≥ 3 cm and pts with positive SMS more likely to have KPS 60 - 80, T3/T4, or N1 disease. On univariate analysis (UVA) CA19-9 cut at 90 was associated with significant increases in both LRF (trend) and DF; in the gemcitabine arm this was seen in DF, not in LRF; in the 5-FU arm it was seen in both. Results were similar at the 180 cut point and continuously. SMS on UVA was not associated with increase in LRF/DF; see Table. On MVA, CA19-9 > 90 was significantly associated with LRF and DF; positive SMS showed only a trend for DF. Conclusions: Postresection CA19-9 has significant association with both LRF and DF not seen with SMS. These findings support continued use of RT in trials and consideration of dose intensification among pts with elevated postresection CA19-9. Grants: NCI U10, CA21661, CA37422, CA180868, CA180822. Clinical trial information: 0000000. [Table: see text]
Lewis antigen‑negative pancreatic cancer: An aggressive subgroup
