Gastrointestinal Cancer

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SU_18_2182 - Association of Dosimetric and Treatment Related Factors with Radiation Induced Lymphopenia and Overall Survival among Patients Treated in the FOLFIRINOX Era

Sunday, October 21
1:15 PM - 2:45 PM
Location: Innovation Hub, Exhibit Hall 3

Association of Dosimetric and Treatment Related Factors with Radiation Induced Lymphopenia and Overall Survival among Patients Treated in the FOLFIRINOX Era
R. Sethi1, T. S. Hong1, A. Niemierko1, S. Edgington2, N. Petkovska3, D. Mitra4, B. Noe1, A. S. Parikh1, J. Murphy1, J. W. Clark1, D. P. Ryan1, C. Fernandez-del Casti1, K. Lillemoe1, C. R. Ferrone1, and J. Y. Wo5; 1Massachusetts General Hospital, Boston, MA, 2Massachusetts general hospital, Boston, MA, 3Masschusetts General Hospital, Boston, MA, 4Brigham and Women's Hospital, Boston, MA, 5Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA

Purpose/Objective(s): To determine whether radiation to the spleen with concurrent chemotherapy is associated with lymphopenia and ultimately worse survival outcomes in patients with locally advanced pancreatic cancer.

Materials/Methods: Retrospective review of 92 pancreatic cancer patients treated at Massachusetts General Hospital with neoadjuvant FOLFIRINOX for 8 cycles followed by consolidative pre-operative RT (median dose 50.4 Gy) with concurrent capecitabine and surgical resection (39%) from 2010-2016. Absolute lymphocyte count (ALC) was recorded at baseline, post-chemotherapy and post-RT. Basic clinical and demographic variables were collected for all patients. DVH parameters were collected for both spleen and liver.

Results: Median ALC was similar before and after neoadjuvant chemotherapy (1.4 vs. 1.3; p=0.23), but declined significantly after chemo-RT (1.4 vs. 0.6, p<0.001). Median hemoglobin (HgB, 12.9 vs. 11.6, p<0.001) and platelets (223.5 vs. 156.0, p<0.001) also significantly declined after chemo-RT. On multivariable logistic regression, higher risk of post-RT grade IV lymphopenia was associated with lower baseline ALC count (p=0.001), female gender (p=0.001), no surgical resection (p=0.03), and larger spleen volume (p=0.003). On multivariable Cox regression, at a median follow-up of 13.5 months, improved overall survival was associated with having a surgical resection (p=0.001), younger age (p=0.02), and lower spleen V5 (p=0.003), but not gender, pre/post-RT ALC or any other spleen/liver DVH parameters.

Conclusion: Chemo-RT for pancreatic cancer is associated with a significant decline in ALC. Gender, baseline ALC and spleen volume predict for post-treatment ALC. In our series, in the setting of FOLFIRINOX and improved rates of resection, ALC was not associated with overall survival. Table 1: Change in blood count over the course of treatment
Baseline Post-Chemo Post-RT Baseline vs. Post Chemo Post-Chemo vs. Post-RT Baseline vs. Post-RT
Lymphopenia
71 (77% 68 (74%) 22 (24%) P=0.72 P<0.001 P<0.001
Grade III 18 (20%) 22 (24%) 38 (41%)
Grade IV 3 (3%) 2 (2%) 32 (35%)
ANC, median (IQR) 4.3 (3.2, 6.2) 4.2 (3.0, 5.9) 2.9 (2.3, 3.9) P=0.29 P<0.001 P<0.001
ALC, median (IQR) 1.4 (1.0, 2.0) 1.3 (1.0, 1.6) 0.6 (0.4, 0.9) P=0.23 P<0.001 P<0.001
ANC/ALC ratio, median (IQR) 3.1 (2.0, 5.3) 3.2 (2.2, 5.1) 5.2 (3.4, 8.6) P=0.80 P<0001 P<0.001
WBC, median (IQR) 6.8 (5.2, 9.0) 6.5 (4.9, 8.6) 4.5 (3.5, 5.3) P=0.23 P<0.001 P<0.001
HgB, median (IQR) 12.9 (12.1, 13.9) 11.3 (10.3, 12.2) 11.6 (10.1, 12.8) P<0.001 P=0.21 P<0.001
Platelets, median (IQR) 223.5 (169.0, 298.5) 172.5 (127.5, 217.5) 156 (114.5, 200.0) P<0.001 P=0.094 P<0.001

Author Disclosure: R. Sethi: None. T.S. Hong: Research Grant; Novartis, Taiho. A. Niemierko: None. B. Noe: None. A.S. Parikh: None. J. Murphy: None. J.W. Clark: None. C. Fernandez-del Casti: None. J.Y. Wo: None.

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