NECs were previously classified as small cell carcinomas (SCCs), large cell neuroendocrine carcinomas, or poorly differentiated neuroendocrine carcinomas [
3]. NEC is a poorly differentiated, high-grade, malignant neoplasm composed of small cells or intermediate to large cells. In the digestive system, NECs have been reported in the esophagus, the ampulla of Vater [
4], the pancreas [
5], and the gallbladder [
6]. However, NECs in the bile duct are extremely rare.
We conducted a PubMed systematic literature search (1985–2014) using keywords such as “neuroendocrine carcinoma,” “small cell,” and “biliary tract,” and found only 23 reported cases of NEC of the extrahepatic biliary tracts, excluding the intrahepatic bile duct, the gallbladder, and the ampulla of Vater (Table
1, [
7‐
29]). SCC was the most common histologic subtype of NEC of the extrahepatic bile ducts (19 of 23 cases; Table
1). There were only 3 cases of large cell carcinomas of the common bile duct (cases 21 to 23, Table
1). NEC can occur anywhere in the extrahepatic bile duct, but the middle portion of the common bile duct appears to be the most common site of involvement. The prognosis for NEC of the bile duct appears to be poor. Of the 23 cases with follow-up data, 57 % (12/23) of the patients died 3 to 20 months after surgery, and only 2 patients were reported to have survived more than 2 years. NEC of the biliary system has a high incidence of distant metastasis [
15,
16,
19,
20,
22,
24‐
29]. Consequently, it has a poor prognosis, and surgical resection alone is not an effective treatment. A report by Levenson revealed that there is no survival benefit from using surgery to treat either small cell lung cancer or extrapulmonary SCC [
30]. This may be because the most important prognostic factor is the extent of disease at diagnosis, and most patients with extrapulmonary SCC already have occult metastasis [
30]. Of the 12 patients died within 20 months after surgery, 9 cases were identified their recurrence pattern and all of them were distant metastases [
15,
16,
19,
20,
22,
24,
26,
28,
29]. Meanwhile, the long survival 2 cases had locoregional lymph node metastases without distant metastasis [
13,
27]. Since NEC of the biliary system had a high incidence of distant metastasis, locolegional lymph node metastasis could not be a prognostic factor. In the report of 37 cases of neuroendocrine tumor of ampulla of Vater, the authors did not find any prognostic value of the locoregional lymph node metastases and lymphadenectomy [
31].
Table 1
Neuroendocrine carcinoma of the extrahepatic bile duct. Review of the literature
1 | Sabanathan (1988) | 67 | M | Small cell | Bm | 5 cm | Palliative bypass and chemo. | 6 months, alive |
2 | Van der Wal (1990) | 55 | M | Small cell + Adenoca. | Bm | 4 cm | Resection | N.A. |
3 | Nishihara (1993) | 64 | M | Small cell + Adenoca. | Bh-Bs | 1.9 cm | Resection | 8 months, alive |
4 | Yamamoto (1998) | 71 | F | Small cell + Adenoca. | Bh | 6 cm | Resection | 8 months, dead |
5 | Kim (2000) | 64 | M | Small cell + Adenoca. | Bm | 3 cm | Resection | 1 month, alive |
6 | Miyashita (2001) | 85 | F | Small cell | Bi | 3 cm | Palliative bypass | 5 months, dead |
7 | Edakuni (2001) | 82 | F | Small cell + Adenoca. | Bm | 6 cm | Resection | 45 months, alive |
8 | Kuraoka (2003) | 75 | M | Small cell | Bi | 4.5 cm | Resection | 5 months, alive |
9 | Hazama (2003) | 60 | M | Small cell | CBD | 0.3 cm | NAC and resection | 12 months, dead |
10 | Arakura (2003) | 70 | F | Small cell | Bm | 3 cm | Resection and chemo. | 14 months, dead |
11 | Park (2004) | 60 | F | Small cell | Bs-Bm | 3 cm | Resection | 5 months, dead |
12 | Thomas (2005) | 54 | M | Small cell | Bh-CBD | N.A. | Resection | 6 months, alive |
13 | Kaiho (2005) | 66 | F | Small cell + Adenoca. | Bm | 3.5 cm | Resection and chemo. | 8 months, dead |
14 | Sato (2006) | 68 | M | Large cell + Adenoca. | Bi | 2 cm | Resection and chemo. | 3 months, dead |
15 | Viana Miguel (2006) | 76 | M | Small cell | Bm | N.A. | Resection, chemo. and irraiation | 5 months, alive |
16 | Jeon (2006) | 65 | M | Small cell | Bs-Bm | 2 cm | Resection and chemo. | 12 months, dead |
17 | Nakai (2008) | 32 | M | Small cell | CBD | N.A. | N.A. | N.A.(autopsy) |
18 | Arakura (2008) | 75 | M | Small cell | Bh-Bs | 6.5 cm | Chemo. and irradiation | 10 months, dead |
19 | Hosonuma (2008) | 69 | F | Small cell | Bs-Bm | 3 cm | Biliary drainage | 2 months, alive |
20 | Okamura (2009) | 62 | M | Small cell | Bm | 3 cm | NAC, resection and irradiation | 20 months, dead |
21 | Yamaguchi (2009) | 77 | F | NEC | Bi | N.A. | Resection and chemo. | 27 months, alive |
22 | Demoreuil (2009) | 73 | M | Large cell + Adenoca. | Bh-Bs | 3 cm | Resection and chemo. | 12 months, dead |
23 | Sasatomi (2013) | 76 | M | Large cell | Bh-Bs | 5 cm | Resection | 21 days, dead |
24 | Current report (2014) | 70 | F | Small cell | Bh | 5 cm | Resection and chemo. | 10 months, alive |
If there is a biopsy-proven preoperative diagnosis of NEC, then preoperative chemotherapy can improve the prognosis in comparison to surgery alone or surgery with adjuvant chemotherapy. Hazama et al. revealed that neoadjuvant chemotherapy followed by surgery resulted in an excellent response for SCC of the common bile duct [
15]. Okamura et al. reported that multidisciplinary management, consisting of preoperative chemotherapy, a curative resection, adjuvant chemotherapy, and radiation therapy, may scontribute to a prolonged survival for SCC of the common bile duct [
26]. In most cases of NEC of the biliary system diagnosed from pathological findings of resected specimens, surgical resection followed by adjuvant chemotherapy is the generally accepted optimal treatment.
Although there is no established standard treatment for extrapulmonary SCC, chemotherapy should be attempted, if possible, because SCC is often chemosensitive [
32]. The recommended chemotherapy regimen for extrapulmonary SCC is the same as that for small cell lung cancer. For patients with a diagnosis of the small cell type of NEC who are able to undergo surgical resection, adjuvant chemotherapy consisting of cisplatin and etoposide is also recommended for prevention of systemic recurrence [
33,
34].