E. E. McGillivray1, M. Hill1, E. O’Halloran1, S. Murthy1, C. Mayemura1, K. Liang1, N. Goel1, J. Farma1, A. Karachristos1, J. Hoffman1, S. S. Reddy1 1Fox Chase Cancer Center,Department Of Surgical Oncology,Philadelphia, PA, USA
Introduction: The benefits of neoadjuvant therapy in the treatment of pancreatic adenocarcinoma are well known, and with its routine use, pathologic complete response (pCR) has been observed in post-resection specimens. We report our experience with patients who underwent total neoadjuvant therapy (TNT) and had a pCR.
Methods: We conducted a retrospective chart review of all patients who received TNT and underwent a pancreatoduodenectomy, distal or total pancreatectomy at our tertiary care institution from 2002-2018 (n=80). Total neoadjuvant therapy was defined as chemotherapy alone (Gemcitabine or Fluoropyrimidine (5FU) based regimens), followed by radiosensitizing chemotherapy with radiation. Clinical data and pathological information were reviewed, and pCR was defined as those specimens with no remaining tumor cells identified. Preoperative serum CA19-9 levels were analyzed using unpaired T-Tests. Disease free survival (DFS) and overall survival (OS) were examined and compared using the Cox proportional hazard model.
Results: Eight of the 80 patients (10%) were noted to have a pCR. The average age of diagnosis was 61 (46-83), and 50% were male. Clinical stage was stage II (n=5, 62.5%), followed by stage III (n=2, 25%) and stage I (n=1, 12.5%). The median initial CA19-9 was 429.5 U/mL (normal: 0-37), and the median post neoadjuvant CA19-9 was 25.6 U/mL. Overall, 75% of pCR patients experienced a greater than 50% reduction in their CA19-9 values compared to 60% in the non-pCR group (p=0.436). Of the 8 patients, 63% received Gemcitabine based TNT, and 37.5% received 5FU based TNT. Postoperative adjuvant chemotherapy was given to 1 (12.5%) patient 4.6 months after surgery. The 2 year OS rate in the pCR group was 100% with a median OS of 42.2 months, while the 2 year OS for patients that did not have a pCR (n=72) was 61% with a median OS of 31.5 months (p=0.013). Median DFS was 33.6 months in pCR patients compared to 24.9 months in the non-pCR group (p=0.0032). Recurrence was documented in 3 (37.5%) patients with pCR with a median time to recurrence of 26.7 months, compared to recurrence in 41 (56.9%) patients in the non-pCR group with a median time to recurrence of 21.3 months.
Conclusion: Although uncommon, patients who undergo TNT and have a pCR have improved outcomes over those who do not. More investigation is needed into determining which pre-operative therapies and patient factors contribute to a pCR.