Currently, there is strong evidence in favor of metastasectomy for CRC in carefully selected patients [1–7]. However, most of the literature on metastasectomy for CRC pertains to the resection of liver or lung metastases and the significance of the resection of pancreatic and retroperitoneal (aortic bifurcation) lymph node metastases remains uncertain, since resectable lesions in these areas are much less common than liver and lung involvement.
Metastases to the pancreas are relatively uncommon. Among them, CRC is very rare as a primary site and accounts for 5.5–7.8 % of metastatic pancreatic malignancies [9–11]. Therefore, little is known about the therapeutic benefits of pancreatic metastasectomy in CRC [9–13]. It was previously reported that the median survival time (MST) and the 5-year overall survival (OS) were 54 months and 27 %, respectively, after pancreatic metastasectomy for CRC, although the number of patients was small . These outcomes were similar to those for hepatic metastasectomy, suggesting that aggressive surgery for pancreatic metastases might be beneficial in carefully selected patients. As for the selection of patients for pancreatic metastasectomy, primary cancer type, controlling the primary site, isolated metastasis, resectability of the metastasis, and patient fitness were presented as criteria . In addition, it was also suggested that, if the patient had extra-pancreatic metastasis, pancreatic metastasectomy should be an option as long as all metastatic sites could be resected. On the other hand, Sperti et al. suggested that pancreatic metastasectomy for CRC may be considered palliative treatment, and an aggressive surgical approach may be advocated in selected patients, in particular, in symptomatic patients with isolated pancreatic metastasis .
The reported incidence of isolated retroperitoneal lymph node metastases from CRC is 1–2 % [14–16]. As for the benefits of the surgical resection of retroperitoneal lymph node metastases from CRC, except for the reports only about paraaortic lymph node metastasis, few reports showed favorable outcomes in selected patients [17–19]. Two studies defined retroperitoneal lymph node metastases as lymph node metastases limited by the ureters laterally, iliac vessels inferiorly, and the retropancreatic area  or the celiac area  superiorly. The MST after the complete resection of retroperitoneal lymph node metastases from CRC was 53–60 months, and the 3-year OS was 63–81 %. Furthermore, these reports included patients with extra-retroperitoneal metastases, such as liver, lung, peritoneal, and inguinal lymph node metastases, and the number of metastatic sites  or extra-retroperitoneal metastases  was not significantly associated with the outcome. In addition, Shibata et al. showed that the resection of isolated retroperitoneal recurrences was significantly associated with better survival compared with exploration only (MST, 40 versus 3 months) . Moreover, for patients undergoing retroperitoneal metastasectomy, a negative surgical margin and smaller tumor size (≤5 cm) predicted a better prognosis . Taken together, these findings suggest that the surgical resection of retroperitoneal lymph node metastases from CRC could improve survival in selected patients, even in the presence of extra-retroperitoneal metastasis. In addition, complete resection of the metastases with negative surgical margins would be crucial to improve survival.
In the present case, the simultaneous resection of both the metachronous retroperitoneal lymph node and pancreatic metastases from rectal cancer was successfully performed. Furthermore, this patient has had prolonged survival. In a review of the English literature, no reports with detailed clinical information on patients undergoing resection of both the retroperitoneal lymph node and pancreatic metastases from CRC could be identified. To the best of our knowledge, this is the first case with long overall survival and disease-free survival after the resection of these lesions. In this case, the metastatic lesions were located in the two organs. However, both metastatic lesions could be resected completely. Moreover, good control of the primary site was achieved, patient fitness was good, and the retroperitoneal lymph node metastasis was small in size. Collectively, these factors might have contributed to the long-term survival after metastasectomy in this case.
On the other hand, the therapeutic benefits of preoperative or postoperative chemotherapy for retroperitoneal lymph node or pancreatic metastases from CRC are almost unknown. There was heterogeneity among the studies in the use of adjuvant therapy, the chemotherapeutic agents used, and so on. Therefore, it is difficult to determine whether these multimodality treatments have therapeutic benefits compared with surgery alone. However, currently, anticancer agents and molecular targeted agents have made remarkable progress, and therefore, there will be advantages of multimodality treatment for more aggressive CRC, such as disease with retroperitoneal lymph node and/or pancreatic metastases.
In conclusion, an acceptable prognosis could be expected by the potentially curative resection of metastases from CRC, even if they are located in the retroperitoneal lymph nodes and/or the pancreas, in carefully selected patients. Although the outcomes of chemotherapy for CRC have improved markedly, complete cure has not been achieved. Therefore, whenever possible, an aggressive surgical approach should be included in the multimodality treatment of metastatic CRC.