In patients with adenocarcinoma of the head of the pancreas, one of the factors predicting long-term survival is the absence of metastatic lymph nodes [13, 14]. Therefore, to increase survival, extended lymphadenectomies have been performed since the 1990s. However, this extended procedure was not found to be beneficial for overall survival and seemed to be associated with increased morbidity compared with the standard procedure .
Para-aortic lymph node metastasis has been observed in around 14% to 26% of patients who underwent pancreaticoduodenectomy [7–12]. Thus far, there have been six retrospective surveys on the survival of patients with pancreatic ductal adenocarcinoma with para-aortic lymph node metastasis, and no patient survived longer than 5 years (Table 1). However, our patient survived for more than 10 years, although the tumor recurred in the perineural tissue of the SMA. Several factors for long survival times for pancreatic cancer patients have been reported, including a low pre CA19-9 level, the negativity of the dissected margin of the tumor , tumor differentiation [2, 6, 17] and the number of lymph node metastases . Massucco et al. claimed that not only the number but also the localization of the metastases determines the prognosis . In our case, we assume that the long survival time is due to the characteristics of the tumor and the extent of the operation: (1) the original tumor was a well-differentiated adenocarcinoma, (2) it showed good response to chemotherapy and (3) an extended lymphadenectomy was performed, which achived a negative margin status.
Egawa et al. reported to the National Pancreatic Cancer Registry that patients living longer than 5 years after curative resection are those who have well-differentiated primitive tumors, such as a papillary carcinoma or a well-differentiated adenocarcinoma, with good chemosensitivity [2, 17]. Our patient had a well-differentiated carcinoma and was treated with gemcitabine for 3 years. The perineural recurrence around the SMA almost completely vanished with this treatment. The long survival time is apparently due to the good response of the tumor to the gemcitabine treatment. However, after a 2-year interval, the tumor recurred again and showed no progression or regression on further treatment with gemcitabine. Therefore, surgical resection was deemed necessary. Recently Marechal et al. reported that high activities of gemcitabine transport and metabolism proteins are important for long survival times after gemcitabine adjuvant therapy , suggesting that a tumor that responds well to gemcitabine treatment is genetically different from a non-responder. Genetic alterations that affect a tumor’s response to gemcitabine treatment should be analyzed when selecting patients for extended lymphadenectomy.
Also, the extended lymphadenectomy seemed to be important for our patient. Indeed, we did not find any recurrent tumor around the aorta but in the perineural tissue around the SMA. Although randomized trials have concluded that the addition of extended lymphadenectomy and retroperitoneal soft tissue clearance does not significantly improve overall survival , surgical resection has provided the only chance for long-term survival in pancreatic cancer patients, and exeresis of the metastatic lymph node may be worthwhile for patients with chemotherapy-responsive and well-differentiated pancreatic cancer defined by ultrasound-guided fine needle aspiration cytology.
Recently, Kato et al. reported that initially unresectable pancreatic cancer patients with a long-term favorable response to chemotherapy have long survival times after adjuvant surgery . They found 50% of these patients survived for more than 5 years. Interestingly, their analysis showed that distant metastasis, such as peritoneal dissemination and liver metastasis rather than local invasion, results in poor prognosis. But they found only one case of metastasis in the para-aortic lymph nodes. In our case, the tumor recurring around the SMA had a good response to gemcitabine and was successfully resected with at least 1 year of disease-free survival. Therefore, neoadjuvant chemotherapy or adjuvant surgery could be an effective choice for patients with local recurrence even for pancreatic cancer.