For the pancreatic cancer patients, extended operation has been an effective treatment, especially when it is combined with resection and/or reconstruction of major mesenteric vessel and multivisceral resections (MVR).13 Morbidity of the head pancreatic cancer is higher than pancreatic body or tail. Meanwhile, the head pancreatic cancer is commonly accompanied by obstructive jaundice, which is associated with pruritus, liver dysfunction, and recurrent attacks of cholangitis that significantly affect the life quality of patients. Resolving biliary obstruction, through surgical bypass or placement of a biliary stents by cutaneous or endoscopic approach, is very critical to these patients. 14
In our study, 5 patients died of infection of biliary tract. Among them, 4 patients received ERBD, which was used to drain bile. However, infection, particularly abdominal infection, was a common complication. Deep abdominal infections, including intra-abdominal abscess and peritoneal infection, were diagnosed by increased white blood cell count, and positive drainage-fluid culture, signs of peritonitis or were confirmed by CT scan and puncture drainage15. Infection caused by ERBD has been illustrated in several studies and is with high incidence rate.15, 16 The deep abdominal infection incidence in the research of Guo-Qiang Zhang was 43.1%15. Intestinal bacteria reversely infected biliary system, which was prone to cause repeated infection. Moreover, to advanced pancreatic cancer, cachexia was one of the complications with hypoimmunity. The risk of infection thus increased and caused serious consequence.
In our clinical work, PTCD was a choice of reducing the severe infection risk, but we need more enrolled PTCD-treated patients to confirm the result. Therefore, due to the need of always carrying external drainage bags, it was not accepted by some patients.
Palliative bypass surgery was also a method to treat pancreatic cancer, which mainly applied to relieve symptom (ileus, obstructive jaundice, neurotomy, etc.) Burdelski showed that median overall survival time after MVR was longer than that after palliative bypass. ( 16 vs 6 months, P<0.001). However, not all patients would receive MVR, even some advanced pancreatic cancer patients didn’t receive R0 resection or even only received R1 resection (microscopic residual tumor) or R2 resection (macroscopic residual tumor), which affected prognosis obviously. Gillen reported median survival times of R2 resection were 8.2 months and that of palliative bypass procedures were 6.7 months.17
Chemotherapy has been an effective treatment. Von Hoff DD showed that the one-year and two-year survival rates was 35% and 9% in the nab-paclitaxel-gemcitabine group versus 22% and 4% in the gemcitabine group. The median progression-free survival was 5.5 months and 3.7 months, respectively.18 Conroy reported the patients’ median overall survival time of the FOLFIRINOX group and gemcitabine group was 11.1 months and 6.8 months, respectively. Meanwhile, median progression-free survival of the two groups was 6.4 months versus 3.3 months.19
Our results showed median survival time of all patients was 8 months, 1-year overall survival rates 32% and progression-free rates of 1-year 85% by palliative SBRT, which was a satisfactory treatment compared with palliative resection and chemotherapy.
The option of dose fraction was taken into account in our study. From a well-known, lower fraction received higher biologic equivalent dose (BED), which brought high local control rate but also high risk of normal tissues injury theoretically. According to the surrounding organs, we gave the patients 39-66Gy as total prescribed dose and 4-10Gy as single prescribed dose. For location of tumor being closed to stomach, duodenum or bowel, the single prescribed dose was lower, such as 4 to 5Gy. Conversely, the single prescribed dose was higher, such as 6 to 10Gy. Previous studies reported that with 25Gy SBRT in 1 fraction, incidence of acute grade ≥ 3 GI toxicity was 33% in Koong’s research,8 and 5% in Chang’s. 9Hoyer reported 79% patients received grade ≥ 3 GI toxicity after 45Gy/3f by SBRT.7 Our result showed the incidence of acute toxicity was 6.45% during the treatment, which was among our acceptable range. Sadly, during the follow-up period, the majority of patients didn’t receive gastroscope or colonoscopy examination, which caused unknown gastrointestinal conditions, such as ulcer, hemorrhage, etc. In addition, among 7 deaths with unknown causes, we reviewed the radiotherapy plan, the doses of stomach, duodenum and bowel were all lower than tissue tolerance dose threshold. However, the possibility of complications of intestinal radiotherapy cannot be absolutely excluded because of individualities.