(P013) The Role of CA 19-9 in Patients Receiving Stereotactic Body Radiation Therapy for Locally Advanced Pancreatic Cancer

April 15, 2016

Although CA 19-9 does not appear to have large prognostic implications in patients with locally advanced pancreatic cancer who receive induction chemotherapy followed by SBRT, it is suggested to have predictive ability.

Lauren M. Rosati, BS, Avani S. Rao, MD, Amy Hacker-Prietz, MS, PAC, Matthew J. Weiss, MD, Christopher L. Wolfgang, MD, PhD, Timothy M. Pawlik, MD, MPH, PhD, John L. Cameron, MD, Martin A. Makary, MD, MPH, Ana DeJesus Acosta, MD, Dung T. Le, MD, Lei Zheng, MD, Daniel A. Laheru, MD, Susannah G. Ellsworth, MD, Joseph M. Herman, MD, MSc; Johns Hopkins University School of Medicine

BACKGROUND: Carbohydrate antigen 19-9 (CA 19-9) has historically been used as a prognostic indicator in patients with pancreatic cancer. This study was conducted to determine its role in patients with locally advanced pancreatic cancer (LAPC).

METHODS: From July 2010 until April 2015, a total of 136 patients with LAPC were treated with definitive stereotactic body radiation therapy (SBRT) at Johns Hopkins Hospital. Eighteen (13%) of these patients were palliative-intent cases and were excluded from the analysis. CA 19-9 levels were analyzed at three time points: presentation (n = 108), pre-SBRT (n = 92), and post-SBRT (n = 94). A cutoff of 90 U/mL was used in addition to the median value at each time point. Survival estimates were calculated using Kaplan-Meier statistics, and the Mann-Whitney U test was used to compare CA 19-9 levels with surgical outcome.

RESULTS: At baseline, neither CA 19-9 ≤ 90 U/mL nor CA 19-9 ≤ 194 U/mL (median) was found to be significantly associated with superior survival on univariate analysis. Prior to SBRT, improved survival with CA 19-9 ≤ 90 U/mL reached borderline significance (22.6 mo vs 16.1 mo; P = .09), while CA 19-9 ≤ 65 U/mL (median) reached significance (22.9 mo vs 15.7 mo; P = .03). After SBRT, neither CA 19-9 ≤ 90 U/mL nor CA 19-9 ≤ 65 U/mL (median) was found to be of prognostic value.

Of note, 33 (28%) of the 118 analyzable patients with LAPC successfully went on to undergo surgery. Mann-Whitney U test revealed that CA 19-9 ≤ 90 U/mL at presentation, prior to SBRT, and after SBRT was significantly associated with surgical resection (all P < .02).

CONCLUSIONS: Although CA 19-9 does not appear to have large prognostic implications in patients with LAPC who receive induction chemotherapy followed by SBRT, it is suggested to have predictive ability. Patients with CA 19-9 ≤ 90 U/mL during the course of definitive therapy appear to have a higher likelihood of being able to undergo surgery.

Proceedings of the 98th Annual Meeting of the American Radium Society - americanradiumsociety.org