Given the task definition and input, reply with output. Given a passage, construct a question on the basis of the information present in the passage. Construct the question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) it answer uses text phrases from the passage. Avoid creating questions that (i) can't be answered correctly without actually understanding the passage and (ii) uses the same words or phrases given in the passage.

This study was undertaken to determine the survival benefit of extending resections to obtain microscopically negative margins after positive intraoperative frozen sections.', 'The impact of residual microscopic disease after pancreaticoduodenectomy is currently a point of controversy. It is, however, generally believed that microscopically positive margins negatively impact survival and this may be improved by ultimately achieving negative margins.', 'Since 1995, patients undergoing pancreaticoduodenectomy for pancreatic adenocarcinoma have been prospectively followed. Margin status has been codified as macro/microscopically negative (R0) or macroscopically negative/microscopically positive (R1). The impact of margin status on survival was evaluated utilizing survival curve analysis. Data are presented as median, mean +/- SD where appropriate.', 'For pancreatic adenocarcinoma, 202 patients underwent pancreaticoduodenectomy. R0 resections were achieved in 158 patients, 17 of whom required extended resections to achieve complete tumor extirpation after an initially positive intraoperative frozen section (R1 --> R0). R1 resections were undertaken in 44 patients. Median survival for patients undergoing R0 resections was 21 months, 26 +/- 23.4 months versus 13 months, 17 +/- 21.0 months for patients undergoing R1 resections (P = 0.02). Median survival for patients undergoing R1 --> R0 resections was 11 months, 16 +/- 17.3, (P = 0.001). Margin status had a significant correlation with "N" stage and AJCC stage but not "T" stage.
Is survival after pancreaticoduodenectomy improved by extending resections to achieve negative margins?