25 patients received surgical treatment after conversion therapy and achieved a R0 rate of 84%, of which the R0 rate of patients with LAPC was 87.50%. The R0 rate of patients with surgery first was 73.68%. The R0 rate in the patients with unresectable pancreatic cancer was improved to some extent by conversion therapy. Studies have reported that appropriate chemotherapy can increase the possibility of surgical resection of initial unresectable pancreatic cancer, which is beneficial to prognosis and long-term survival(17-19).
Currently, the main treatment for URPC is chemotherapy combined with or without radiotherapy. For patients with unresectable LAPC receiving chemotherapy and radiotherapy, the mOS was 11-15 months, and the mPFS was 10.4-12 months(20, 21). For patients with mPC, with the application of FOLFIRINOX and gemcitabine plus albumin paclitaxel, the mOS was extended to 5 -11.1 months, and the mPFS was extended to 3.7-5.5 months(13, 22, 23). The prognosis and long-term survival of pancreatic cancer are still unsatisfactory. The subjects of this study were 25 patients with URPC who had no chance of surgical resection. The mOS was 28 months and the mPFS was 12 months. The survival time after conversion therapy is significantly longer than that of pancreatic cancer patients after traditional palliative care. After conversion therapy, the median OS and PFS of patients with mPC were not significantly different from those of patients with LAPC. We found that conversion therapy can significantly improve the OS and PFS of patients with mPC.
Whether surgical resection is an option for patients with LAPC has been discussed for a long time(24, 25). In 2004, a multicenter randomized controlled study in Japan showed that the effect of surgery for LAPC was better than that of radiotherapy and chemotherapy(26). Surgery is also being tried for advanced pancreatic cancer. Shrikhande et al reported that the median survival time of patients with liver metastases from pancreatic cancer after R0/R1 resection was longer than without surgical resection (11.4 months vs. 5.9 months, p=0.0384)(27). With the advancement of surgical technology and the improvement of chemotherapy regimens, surgery has gradually become a treatment option for patients with URPC. 19 patients with LAPC chose to receive surgery first, achieving an R0 rate of 73.68%, with mOS of 16.5 months and mPFS of 8 months. 25 patients with URPC underwent surgical resection after conversion therapy, and 9 of them had distant metastases. The Kaplan-Meier survival curve showed that conversion therapy prolonged the OS and PFS of patients with URPC compared with surgical treatment. One patient with liver metastases of pancreatic cancer achieved R1 resection, with an OS of 29 months and a PFS of 5 months. One patient with bone metastasis of pancreatic cancer only underwent resection of the primary lesion, with an OS of 35 months and a PFS of 4.5 months. Radical surgery for patients with metastatic pancreatic cancer may benefit the long-term survival of patients even if R0 resection cannot be achieved(28, 29).
The preoperative CA19-9 level is an independent factor that affects the OS and PFS achieved by conversion therapy. The number of lymph node metastases is an independent factor that affects the OS. It has been reported in the literature that low preoperative CA19-9 levels and fewer lymph node metastases are associated with a good prognosis after conversion therapy(19, 30). We found that age, gender, T stage, and distant metastasis are not independent prognostic factors for conversion therapy.
This study has several limitations. First, this is a single-center retrospective study, the small sample size limits the credibility of the conclusions drawn. Second, the 25 patients involved in this study who received conversion therapy were not all assessed as resectable before surgery, and most of the patients' condition was relieved or remained stable. Third, there are individual differences in the response of patients to treatment. Fourth, there may be selection bias.