AC is relatively rare, and the reported incidence is around 7% of all periampullary tumors . The frequency of adenocarcinoma is the highest among all malignant tumors, and differentiation from bile duct cancer, pancreatic cancer, and duodenal cancer infiltration is required. According to the Japanese registry of biliary tract cancer, the resectability rate of AC is 89.4% and the curative resection rate is 93.0%. The 5-year survival rate after resection is 52.8%, which is higher than that of cholangiocarcinoma (32.7%) or gallbladder cancer (41.6%). Thus, AC has a relatively good prognosis. However, patients with distant metastasis have a poor prognosis, and the 5-year survival rate is 0.0% . Chemotherapy is the first choice for advanced AC with distant metastases. According to a recent randomized phase III study from the UK (ABC-02 trial), the combination of GEM and CDDP (GC) has become the current standard for unresectable biliary tract cancer . A Japanese multicenter phase III trial also demonstrated the advantage of GC over GEM alone . In the present case, we started the GC regimen with palliative intent, not as curative treatment. However, a dramatic effect was observed for both the primary and metastatic tumors. Disappearance of the liver metastasis and benign results of the biopsy from the ampulla of Vater offered hope of curative resection.
We searched previous reports and found four case reports describing curative resection of initially unresectable AC due to distant metastases [10,11,12,13]. All reports described favorable outcomes. However, to the best of our knowledge, this is the first report of successful conversion surgery for AC following the achievement of pathological CR in the primary tumor and metastatic lesions.
Recent advances in chemotherapy have led to several cases of successful conversion surgery in patients with advanced biliary tract cancer or pancreatic cancer, as for patients with colorectal cancer [14,15,16]. However, because no comprehensive reports are available, no consensus has been reached regarding the timing of resection, its impact on the prognosis, or the need for postoperative adjuvant therapy. Because of the rarity of the disease, performing well-powered clinical trials of conversion surgery after chemotherapy in patients with AC will be much more limited. We consider that surgical options should be discussed among a multidisciplinary team, at least when dramatic effects of chemotherapy are confirmed, as in our case. Further collection of additional cases is expected.
Because the liver metastasis could not be confirmed during surgery in the present case, there was a concern that pathological CR could not be demonstrated for the liver metastasis. Postoperative adjuvant therapy was not performed because of the long-term neoadjuvant chemotherapy and pathological CR of the primary tumor and metastatic lymph nodes. We will continue close follow-up with particular attention to relapse of liver metastasis.