Relapse rate and relapse patterns in patients undergoing curative resection for Pancreatic Ductal Adenocarcinoma (PDAC): Identifying high risk patients


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Akul Purohit1,Abdullah Malik2,Rahul Deshpande2,Mairead McNamara3,Thomas Satyadas2,Melissa Frizziero4,Saurabh Jamdar2,Rille Pihlak5,Aali Sheen2,Ajith Siriwardena2,Richard Hubner4,Derek O'Reilly2,Juan W Valle3,Nicola De Ligouri Carino2,Angela Lamarca4
1The Christie NHS Foundation Trust,2Hepatobiliary & Pancreatic Surgical Team, Department of Surgery, Manchester Royal Infirmary, Manchester, UK,3Medical Oncology Department, The Christie NHS Foundation Trust, Manchester, UK & Division of Cancer Sciences, University of Manchester, Manchester, UK,4Medical Oncology Department, The Christie NHS Foundation Trust, Manchester, UK,5Medical Oncology Department, The Christie NHS Foundation Trust, Manchester, UK & Division of Cancer Sciences, University of Manchester, Manchester, UK.

Abstract

Background

PDAC has a 5-year relapse rate >80% following curative resection. Identifying patients at higher risk of relapse and factors related with specific patterns of disease spread may inform selection of candidates for closer follow-up.

Method

The outcome of patients with PDAC (Jan’05-Sep’17) who underwent curative resection, and with available follow-up and relapse status data, was analysed retrospectively. The aim was to identify factors associated with higher relapse risk and specific relapse patterns. Kaplan Meier, Log-rank, Chi squared and T-tests were used for analysis.

Results

Of 228 patients, 182 were eligible. Patient characteristics: 55.5% male, median age 65.7 years (95%CI 64.2-67.2), T3 (81.9%), lymph node (N)1 (71.4%), involved resection margin (R)1 (61.5%). Adjuvant chemotherapy was given to 113 patients (62.1%) [5-fluorouracil (5-FU)(38.9%), Gemcitabine (G) (31.9%), G+5-FU (29.2%)-based]. Median overall survival (OS) was 21.6 months (95%CI 17.9-28.9). After a median follow-up of 17.9 months, 143 patients relapsed [relapse rate 78.6%, median time-to-relapse 8.9 months (95%CI 7.7-10.1)]. Median OS was shorter (log-rank p-value <0.001) in the “relapse” group (17.5 months (95%CI 15.9-20.9) vs. “non-relapse” (not reached).

Patients with “relapse” had higher rate of N1 disease (76.2% vs 53.8%; p-value 0.0161). No other factors related with increased relapse rate were identified. Local relapse (59.4%): resection bed (54.6%) +/- regional N (16.8%). Distant relapse (69.9%): median number of organs affected was 1; liver 41.3%, lung 20.9%, peritoneum 11.9%, distant N 4.9%, bone 2.8%, others 2.1%. Three relapse patterns were identified: regional only (30.1%), distant only (40.6%) and combined (regional + distant) (29.3%). Adjuvant chemotherapy reduced the risk of combined relapse (p=0.04).  

Conclusion

Relapse rate following curative resection for PDAC remains high, with predominance for distant recurrence. Patients with N1 disease have the highest risk of relapse and may benefit from closer follow-up.