Journal of Oncology
Volume 2015 (2015), Article ID 304909, 8 pages
http://dx.doi.org/10.1155/2015/304909

Review Article

Small Cell Carcinoma of the Gallbladder: Case Report and Comprehensive Analysis of Published Cases

Carolyn Carrera, Paul Kunk, and Osama Rahma

Division of Hematology and Oncology, Department of Medicine, University of Virginia Health System, Charlottesville, VA 22908, USA

Received 25 September 2015; Accepted 16 November 2015

Academic Editor: Kalpesh Jani

Copyright © 2015 Carolyn Carrera et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract.

Background. Gallbladder small cell carcinoma is a rare and highly aggressive malignancy with no established standard of care treatment. We described here a case report of small cell gallbladder cancer and we then performed a comprehensive review of 72 case reports of this disease. Methods. Published case reports of small cell carcinoma of the gallbladder between 1983 and 2014 were reviewed. Treatment modalities and survival were analyzed for metastatic and localized disease. Results. Median overall survival for all patients was 13 months. Metastatic disease was identified in 72% of cases. Treatment of metastatic disease with chemotherapy showed a significant survival benefit () compared to no chemotherapy, and the use of platinum doublet with etoposide showed a nonsignificant 4-month improvement in survival compared to other chemotherapy regimens (). Adjuvant therapy did not demonstrate an improvement of median overall survival in local disease (). Conclusion. Given the limited available data, systemic therapy with platinum and etoposide should be considered for patients with metastatic small cell carcinoma of the gallbladder. Adjuvant chemoradiation or chemotherapy for treatment of local disease warrants further investigation.

1. Introduction

Small cell carcinoma of the gallbladder is a rare and highly aggressive malignancy that was first described by Albores-Saavedra in 1981 [1, 2]. While small cell carcinoma of the lung comprises approximately 15% of all lung cancers [3, 4], extrapulmonary small cell carcinoma is rare with a reported incidence of 0.1–0.4% [5, 6]. Similar to other extrahepatic biliary tumors, small cell cancer of the gallbladder is associated with cholelithiasis [7] and rarely with paraneoplastic syndromes including Cushing syndrome and paraneoplastic sensory neuropathy [8, 9]. Early metastases to regional and distant lymph nodes, liver, and lungs are common with 66% of patients having evidence of metastatic disease at diagnosis [7]. Median overall survival is reported to be approximately 9 months [6, 7].

Gross pathologic features of gallbladder small cell carcinoma include large tumor size with extensive necrosis and submucosal invasion [10]. Histological features show a proliferation of small round or oval cells arranged in sheets with scant cytoplasm and hyperchromatic nuclei with cytoplasmic neurosecretory granules under electron microscopy [11–13]. Small cell tumors typically express neuron-specific enolase (NSE), while some express synaptophysin, chromogranin, cytokeratin, and Leu-7 [13–15]. Similar to gallbladder adenocarcinoma, there is a high frequency of p53 and p16INK4a mutations [15].

No standard of care exists for treating gallbladder small cell carcinoma. While the overall survival benefit of chemoradiation or chemotherapy has been extrapolated from a meta-analysis of patients with high-risk biliary tract cancers [16], such benefit in patients with small cell histology remains unclear. Published treatment regimens for gallbladder small cell carcinoma are highly variable, including resection, radiation, and/or a variety of chemotherapy regimens [7].

Here, we present a case of metastatic gallbladder small cell carcinoma. We subsequently performed a comprehensive analysis of published case reports of gallbladder small cell carcinoma with an emphasis on the varying treatment strategies.

An 89-year-old man with a history of dementia and multiple myeloma presented with one month of right-sided abdominal pain. Noncontrasted CT scan of the abdomen revealed a 3 × 4 cm gallbladder mass with probable hepatic extension and enlarged portacaval, cystic, and peripancreatic nodes. MRI of the abdomen confirmed a bulky gallbladder tumor measuring 5.6 cm with direct extension into the liver. Innumerable hepatic and periportal nodal metastases with mass effect on the cystic duct, as well as peripancreatic and right diaphragmatic nodal involvement, were also seen (Figure 1). CT scan of the chest showed several indeterminate pulmonary nodules, mediastinal adenopathy, and spinal lytic lesions, but no primary lung mass. An ultrasound-guided FNA of one of the liver lesions showed small and fragile epithelioid cells with little cytoplasm and fine chromatin in addition to abundant apoptotic bodies and mitotic figures (Figure 1). Given the presence of gallbladder mass and subsequent FNA results, the diagnosis of gallbladder small cell carcinoma was made. Due to the patient’s poor functional status and multiple medical comorbid conditions, he elected to pursue hospice care and passed away 3 months after diagnosis.

(a)

(b)

Figure 1: Patient case MRI and FNA of liver lesion. (a) MRI of the abdomen showed a bulky gallbladder tumor measuring 5.6 cm with direct extension into the liver, innumerable hepatic and periportal nodal metastases which exerted mass effect on the cystic duct, and peripancreatic and right diaphragmatic nodal involvement. (b) Ultrasound-guided biopsy of a metastatic liver lesion shows small and fragile epithelioid cells with little cytoplasm and fine chromatin. Abundant apoptotic bodies and mitotic figures were seen consistent with small cell carcinoma.

2. Materials and Methods

Case reports between 1983 and 2014 were obtained by searching PubMed using terms of “small cell carcinoma of the gallbladder” and “oat cell carcinoma of the gallbladder.” Patients were classified as having local (involving immediate regional lymph nodes or direct extension into the liver) or metastatic disease (involving distant lymph nodes, satellite liver metastasis, or other organ metastases). We favored staging this disease in a similar manner to small cell lung cancer rather than traditional TNM staging for cholangiocarcinoma given their similar histopathology and aggressive clinical course. Median overall survival was determined for the local and metastatic groups, as well as those with local disease who underwent adjuvant chemotherapy and/or radiation. Patients with metastatic disease were further classified with respect to the chemotherapy regimens they received and analyzed for survival benefit. Autopsy cases and clinical cases that did not report survival data were reported here but excluded from statistical analysis. Kaplan-Meier curves were developed, and was considered statistically significant.

3. Results

3.1. Patient Characteristics

Seventy-two patients with small cell carcinoma of the gallbladder were identified [1–38]. Characteristics of clinical cases are listed in Tables 1 and 2, and autopsy cases are depicted in Table 3. Overall, this included 49 female and 23 male patients with an average age of 62.8 years (range 25–89). Nineteen of these patients were identified at autopsy, leaving 53 patients available for analysis.

Table 1: Clinical characteristics in local disease.

Year
Age
Sex
Histology
Stones
Surgery
Adjuvant chemotherapy
Adjuvant radiation
Survival
Ref.

1
1988
72
F
SCC
No
Yes
None
No
2
[17]

2
1988
68
F
SCC
Yes
Yes
None
No
>59
[17]

3
1990
72
F
SCC
Yes
Yes
None
No
>12
[18]

4
1993
74
M
SCC
N/A
Yes
None
No
>28
[19]

5
1993
61
M
SCC
Yes
Yes
Etop.
No
2
[14]

6
1994
71
F
SCC, adenosquamous
Yes
Yes
None
No
20
[20]

7
1998
76
F
SCC
No
Yes
None
No
>144
[21]

8
1999
57
F
SCC
No
Yes
5-FU
Yes
31
[31]

9
1999
40
M
SCC, moderately differentiated adenocarcinoma
Yes
Yes
5-FU
No
>189
[31]

10
1999
79
M
SCC
No
Yes
Cyclophos., Vinc., Procarb., Pred.
No
3.5
[22]

11
1999
86
F
SCC
Yes
Yes
None
No
5
[22]

12
2000
25
F
SCC
N/A
Yes
None
Yes
>7
[10]

13
2000
81
F
SCC
Yes
Yes
None
No
>5
[12]

14
2002
67
M
SCC, undifferentiated with neuroendocrine features
Yes
No
Cis., Etop.
Yes
11
[23]

15
2002
66
F
SCC, clear cell carcinoma, and adenocarcinoma
Yes
Yes
Chemo N/A
No
36
[24]

16
2009
48
F
SCC
No
Yes
Cis., Etop.
No
>4
[9]

17
2010
47
M
SCC
No
Yes
Cis., Etop.
Yes
>8
[25]

18
2010
41
F
SCC
No
Yes
Chemo N/A
No
>2
[25]

19
2010
70
F
SCC
N/A
Yes
Cis., Etop.
Yes
>15
[6]

SCC = small cell carcinoma; Etop. = etoposide; Cyclophos. = cyclophosphamide; Vinc. = vincristine; Procarb. = procarbazine; Pred. = prednisolone; Cis. = cisplatin; chemo N/A = chemotherapy (agents not identified).

Table 2: Clinical characteristics in metastatic disease.

Year
Age
Sex
Histology
Mets. site
Stones
Chemotherapy
Radiation
Survival
Ref.

1
1981
58
F
SCC
Hilar LN
Y
None
N
4
[1]

2
1984
79
F
SCC
Regional LN, liver
Y
None
N
4
[2]

3
1984
55
F
SCC
LN, liver
Y
Adr., Vinc., Cyclophos., Nitro.
N
11
[2]

4
1984
N/A
F
SCC
Regional LN, liver
Y
None
N
4
[2]

5
1984
52
F
SCC
Liver
N
Adr., Vinc., Cyclophos., Nitro.
N
13
[2]

6
1988
44
M
SCC
LN, liver, omentum, and colon
N
None
N
>2
[17]

7
1988
75
F
SCC
Liver
N
None
N
9
[17]

8
1988
56
F
SCC
Liver, abdominal wall
N
None
N
2
[17]

9
1991
71
F
SCC, adenocarcinoma
Liver, hilar LN, and peritoneum
N
None
N
4
[26]

10
1992
62
F
SCC
Liver, duodenum
N
None
N
5
[27]

11
1992
60
M
SCC
LN, liver
Y
Cis., Etop.
N
>18
[28]

12
1993
68
F
SCC
LN
N/A
None
N
2
[19]

13
1993
64
F
SCC
LN
N/A
None
N
6
[19]

14
1993
43
F
SCC
LN, liver
N/A
None
N
10
[19]

15
1993
57
M
SCC
Liver
N/A
None
N
N/A
[19]

16
1996
37
F
SCC
LN, liver, and omentum
N/A
Cis., Etop.
N
13
[29]

17
1996
82
M
SCC
LN, liver
N/A
None
N
1
[29]

18
1998
72
M
SCC
Liver
N/A
Platinum, Etop.
N
>16
[11]

19
1998
76
F
SCC, intestinal metaplastic epithelium
LN, liver
N/A
None
N/A
N/A
[30]

20
1999
69
F
SCC, poorly diff. adenocarcinoma
LN, liver, small bowel, and omentum
N
Cis., Etop.
N
44
[31]

21
1999
69
M
SCC
RP LN
Y
Strep., 5-FU
Y
21
[31]

22
1999
71
F
SCC, poorly diff. adenocarcinoma
RP LN, liver, and peritoneum
Y
5-FU
Y
13
[31]

23
2001
62
M
SCC
LN, liver
Y
Cis., Etop.
N
17
[3]

24
2001
56
M
SCC
Liver
Y
5-FU, Cis., Doce., Carbo.
N
13
[32]

25
2001
70
F
SCC
Liver
N/A
None
N
1
[33]

26
2005
48
M
SCC
LN, liver
N/A
Gem., Cis.
N
7
[34]

27
2005
51
M
SCC
LN, liver
N/A
Gem., Cis.
N
5
[34]

28
2005
47
F
SCC
Liver
N/A
Pac, Ifos., Cis.
N
>12
[35]

29
2005
49
F
SCC
Liver
N/A
Pac, Ifos., Cis.
N
>10
[35]

30
2006
77
F
SCC
LN, liver
N/A
Chemo N/A
N
N/A
[36]

31
2008
76
F
SCC
LN, liver
N/A
Cis., Etop.
N
>10
[37]

32
2011
54
F
SCC
LN, liver
N
Carbo.
N
3
[7]

33
2009
32
F
SCC
LN, liver
N/A
Cis., Etop.
N
>9
[15]

34
2015
89
M
SCC
LN, liver, and lung
N
None
N
3

SCC = small cell carcinoma; LN = distant lymph nodes; RP = retroperitoneal; Adr. = adriamycin; Vinc. = vincristine; Cyclophos. = cyclophosphamide; Nitro. = nitrosourea; Cis. = cisplatin; Etop. = etoposide; Dox. = doxorubicin; Mito. = mitomycin; Doce. = Docetaxel; Carbo. = carboplatin; chemo N/A = chemotherapy (agents not identified); Pac = paclitaxel.

= present case.

Table 3: Autopsy cases.

Year
Age
Sex
Histology
Metastasis
Mets. site
Stones
Ref.

1
1981
55
M
SCC
Y
LN, liver
Y
[1]

2
1981
72
F
SCC
Y
LN, liver
Y
[1]

3
1981
74
F
SCC
Y
LN, lung
Y
[1]

4
1981
65
M
SCC
Y
LN, liver, peritoneum, and pleura
Y
[1]

5
1984
75
F
SCC
Y
LN, liver, and lung
Y
[2]

6
1984
67
F
SCC
Y
LN, liver, and lung
Y
[2]

7
1984
66
F
SCC
N
LN
Y
[2]

8
1984
67
F
SCC
Y
LN, liver, peritoneum, and splenic vein
Y
[2]

9
1984
60
F
SCC
Y
LN, liver, and lung
Y
[2]

10
1984
60
F
SCC
Y
LN, liver, ovary, and peritoneum
Y
[2]

11
1984
48
F
SCC
Y
LN, liver, and lung
Y
[2]

12
1984
72
F
SCC
Y
LN, liver
Y
[2]

13
1984
55
F
SCC
Y
LN, liver, and omentum
Y
[2]

14
1984
50
F
SCC
Y
LN, liver
Y
[2]

15
1988
50
F
SCC
Y
LN, biliary duct, liver, pancreas, duodenum, and colon
N/A
[17]

16
1988
69
M
SCC
Y
LN, liver, biliary duct, duodenum, and lung
Y
[17]

17
1988
73
M
SCC
Y
LN, liver, and pancreas
Y
[17]

18
1991
70
M
SCC, adenocarcinoma
Y
LN, liver, rectum, pancreas, and adrenal
N/A
[38]

19
1993
83
M
SCC
Y
LN, liver, and pancreas
N/A
[19]

3.2. Local Disease

Of the 53 patients analyzed, 20 patients (38%) were identified as having local disease (19 clinical cases and 1 autopsy case). The autopsy case was excluded from data analysis due to lack of survival data (Table 3). As shown in Table 1, average age of patients with local disease was 63 years (range 25–86), and local disease was more common in women (F : M of 13 : 6). Presenting symptoms in this group included abdominal pain, nausea, vomiting, jaundice, pruritus, and weight loss. The most frequently encountered histopathology was small cell carcinoma, but mixed histopathology of small cell carcinoma with adenocarcinoma, adenosquamous, undifferentiated carcinoma with endocrine features, and clear cell carcinoma was identified. Cholelithiasis was identified in 9/16 (56%) patients with local disease.

Treatment of local disease was variable. Eighteen of the nineteen analyzed patients (95%) underwent surgical resection, while only one patient did not undergo cholecystectomy due to extensive fibrosis and adhesions found intraoperatively [23]. Adjuvant treatment with chemotherapy and/or radiation was identified in 10/18 (56%) patients. Most frequently administered chemotherapy regimens included cisplatin/etoposide (4) and 5-FU (2). One patient received etoposide alone [14]. One patient received cyclophosphamide, vincristine, procarbazine, and prednisolone [22]. Two patients underwent chemotherapy with unnamed agents [24, 25]. Five patients underwent radiation to the liver or gallbladder fossa, with one receiving it for bone metastases in the setting of disease recurrence at 24 months [31].

3.3. Metastatic Disease

Metastatic disease accounted for 52 (72%) of the cases. Twenty-two of these 52 patients (42%) were found at autopsy or had unavailable survival data, and therefore they were excluded (Table 3). Thus, only 34 cases with metastatic disease were available for analysis (Table 2). Average age of patients with metastatic disease was 61.5 years (range 32–89), and metastatic disease was more common in women (F : M of 23 : 11). Presenting symptoms in this group were similar to those with local disease and included abdominal pain, nausea, cholestatic jaundice, and weight loss. The most frequently encountered histopathology was small cell carcinoma, but mixed histopathology with adenocarcinoma and intestinal metaplastic epithelium was also seen. Cholelithiasis was identified in 9/17 (53%) patients with metastatic disease. The most common sites of metastases included liver and distant lymph nodes (e.g., retroperitoneal, peripancreatic, hilar, and para-aortic). Other reported metastatic sites included the abdominal wall, omentum, pancreas, adrenal glands, small bowel, and colon.

Administered chemotherapeutic regimens in patients with metastatic disease consisted of platinum agent in combination with etoposide in the majority of the cases (7) followed by 5-FU (2) and gemcitabine/cisplatin (2). One patient received single agent carboplatin [7]. Two patients received adriamycin, vincristine, cyclophosphamide, and nitrosourea [2]. Two patients were identified as having undergone radiation therapy for retroperitoneal disease [31]. One patient was excluded from further analysis due to receiving multiple treatment regimens including platinum/etoposide and 5-FU administered closely together [32].

3.4. Autopsy Cases

Nineteen autopsy cases were identified (Table 3). Eighteen patients (95%) were found to have distant metastases to lymph nodes, liver, lung, peritoneum, pancreas, ovary, adrenal glands, and colon. Autopsy cases were predominately found to be earlier studies with the majority being published before 1990. These cases were excluded from further analysis due to lack of prognostic data.

3.5. Outcomes

Median survival for all patients was 13 months. Patients with local disease demonstrated a statistically significant improvement in median overall survival compared to those with metastatic disease (31 versus 9 months, resp., ) (Figure 2). We were unable to report progression free survival, response, and recurrence rates due to unavailable data from the case reports.

Figure 2: Survival for metastatic versus local disease.

The vast majority of patients with local disease were treated with surgical resection. However, one patient did not undergo cholecystectomy due to extensive fibrosis and adhesions. The patient subsequently received chemoradiation with cisplatin/etoposide and survived 11 months [23]. There were two patients reported to have long-term survival within the local disease group. The first patient survived at least 189 months after surgical resection and adjuvant chemotherapy with a 5-FU-based regimen. The patient had lung and intra-abdominal recurrence but was reported to be alive at the time of publication [31]. The other patient survived more than 144 months after surgical resection without adjuvant treatment [21]. Based on our analysis adjuvant therapy was not found to improve median overall survival () in patients with local disease (Figure 3).

Figure 3: Survival for local disease adjuvant therapy versus no adjuvant therapy.

In contrast, patients in the metastatic group who received chemotherapy had statistically improved median overall survival compared to patients who had no chemotherapy (13 versus 4 months, ) (Figure 4). In a subgroup analysis of patients with metastatic disease who received chemotherapy, the regimen of platinum/etoposide demonstrated a nonsignificant improvement in median overall survival compared to all other chemotherapy regimens (17 versus 13 months, ) (Figure 5). Two patients with metastatic disease underwent radiation for retroperitoneal lymph node involvement with reported survival of 13 and 21 months [31]. Statistical analysis was not performed on this group of patients who received radiation therapy given its small sample size.

Figure 4: Use of chemotherapy for patients with metastatic disease.

Figure 5: Chemotherapy regimen in patients with metastatic disease.

4. Discussion

We performed a comprehensive analysis of 72 cases of gallbladder small cell carcinoma. We found this malignancy to be reported most often in older patients and women. The majority of patients (72%) were found to have metastatic disease at the time of diagnosis, presumably due to the nonspecific presenting symptoms. We found the median overall survival to be 13 months, which is consistent with previously published reports (range of 9–31 months) [3, 6, 7, 31]. Not surprisingly, patients with metastatic disease had worse prognosis compared to those with local disease and benefited from treatment with chemotherapy, mainly platinum and etoposide combination. While our analysis showed no benefit of adjuvant chemotherapy in local disease, a trend toward improved survival was previously established with a multidisciplinary approach involving surgery, adjuvant platinum-based chemotherapy, and radiation therapy (21 months) compared to surgery alone (4 months), adjuvant chemotherapy alone (12 months), and chemotherapy alone (9 months) [6].

The rarity of gallbladder small cell carcinoma and the retrospective nature of our study pose significant limitations to the interpretation of our report. The disease has only been identified relatively recently [1] with only a few published case reports. Furthermore, data on response rates and progression free survival was unavailable from the published case reports, limiting analysis to overall survival benefit.

Small cell cancer of the lung has been studied more extensively given its higher incidence compared to small cell cancer of the gastrointestinal (GI) tract. Treatment of small cell carcinoma of the lung currently consists of chemoradiation in combination with platinum agents and etoposide for limited stage disease and chemotherapy for extensive stage disease based on large clinical studies [39–42]. Given the similar pathology and perhaps biology of small cell cancer of the lung and GI tract, it is not surprising that platinum agents in combination with etoposide provided the most survival benefit (although not statistically significant) in this report.

Due to the low incidence of gallbladder small cell carcinoma, it is unlikely that randomized clinical trials can be feasible to establish the standard treatment of this disease. Accordingly, future clinical trials could be designed to include patients with small cell histology regardless of the tumor origin. Future directions should also focus on better understanding of the molecular biology of these tumors in order to develop more effective therapies. Novel targets such as Bcl-2, VEGF, and delta-like protein 3 (DLL3) are currently being investigated in small cell lung cancer, which, if successful, may be applied to non-small-cell lung cancers [43, 44]. In summary, small cell cancer of the gallbladder represents a clinical challenge in daily practice given the paucity of available clinical data and the lack of randomized studies supporting the analysis of case reports as a clinically meaningful tool.

Conflict of Interests

The authors declare that there is no conflict of interests regarding the publication of this paper.

References

J. Albores-Saavedra, H. Cruz-Ortiz, A. Alcantara-Vazques, and D. E. Henson, “Unusual types of gallbladder carcinoma. A report of 16 cases,” Archives of Pathology and Laboratory Medicine, vol. 105, no. 6, pp. 287–293, 1981.

J. Albores-Saavedra, J. Soriano, O. Larraza-Hernandez, J. Aguirre, and D. E. Henson, “Oat cell carcinoma of the gallbladder,” Human Pathology, vol. 15, no. 7, pp. 639–646, 1984.

H. Fujii, T. Aotake, T. Horiuchi, Y. Chiba, Y. Imamura, and K. Tanaka, “Small cell carcinoma of the gallbladder: a case report and review of 53 cases in the literature,” Hepato-Gastroenterology, vol. 48, no. 42, pp. 1588–1593, 2001.

National Cancer Institute, “PDQ Small Cell Lung Cancer Treatment,” Bethesda, Md, USA, National Cancer Institute, 2015, http://www.cancer.gov/types/lung/hp/small-cell-lung-treatment-pdq

H. F. M. Van der Heijden and Y. F. Heijdra, “Extrapulmonary small cell carcinoma,” Southern Medical Journal, vol. 98, no. 3, pp. 345–349, 2005.

S. Usmani, M. Pazooki, and S. F. Bilgrami, “Small cell carcinoma of the gall bladder: role of adjuvant chemotherapy,” Journal of Gastrointestinal Cancer, vol. 41, no. 1, pp. 84–87, 2010.

A. Mahipal and S. Gupta, “Small-cell carcinoma of the gallbladder: report of a case and literature review,” Gastrointestinal Cancer Research, vol. 4, no. 4, pp. 135–136, 2011.

A. Maitra, M. Tascilar, R. H. Hruban, G. J. Offerhaus, and J. Albores-Saavedra, “Small cell carcinoma of the gallbladder: a clinicopathologic, immunohistochemical, and molecular pathology study of 12 cases,” American Journal of Surgical Pathology, vol. 25, no. 5, pp. 595–601, 2001.

J. Albores-Saavedra, K. Batich, S. Hossain, D. E. Henson, and A. M. Schwartz, “Carcinoid tumors and small-cell carcinomas of the gallbladder and extrahepatic bile ducts: a comparative study based on 221 cases from the Surveillance, Epidemiology, and End Results Program,” Annals of Diagnostic Pathology, vol. 13, no. 6, pp. 378–383, 2009.

N. O. Uribe-Uribe, A. M. Jimenez-Garduño, D. E. Henson, and J. Albores-Saavedra, “Paraneoplastic sensory neuropathy associated with small cell carcinoma of the gallbladder,” Annals of Diagnostic Pathology, vol. 13, no. 2, pp. 124–126, 2009.

U. Mithal, A. Heroor, K. Khan et al., “Small cell carcinoma of gall bladder,” Indian Journal of Gastroenterology, vol. 19, no. 1, article 33, 2000.

J. M. Debois, P. De Vriendt, and K. Charels, “Small cell carcinoma of the gallbladder,” Acta Chirurgica Belgica, vol. 98, no. 3, pp. 110–112, 1998.

S. Matsuo, T. Shinozaki, S. Yamaguchi et al., “Small-cell carcinoma of the gallbladder: report of a case,” Surgery Today, vol. 30, no. 1, pp. 89–93, 2000.

A. K. Johnstone, R. H. Zuch, and K. H. Anders, “Oat cell carcinoma of the gallbladder: a rare and highly lethal neoplasm,” Archives of Pathology and Laboratory Medicine, vol. 117, no. 10, pp. 1009–1012, 1993.

S. Iype, T. A. Mirza, D. J. Propper, S. Bhattacharya, R. M. Feakins, and H. M. Kocher, “Neuroendocrine tumours of the gallbladder: three cases and a review of the literature,” Postgraduate Medical Journal, vol. 85, no. 1002, pp. 213–218, 2009.

A. M. Horgan, E. Amir, T. Walter, and J. J. Knox, “Adjuvant therapy in the treatment of biliary tract cancer: a systematic review and meta-analysis,” Journal of Clinical Oncology, vol. 30, no. 16, pp. 1934–1940, 2012.

K.-J. Guo, K. Yamaguchi, and M. Enjoji, “Undifferentiated carcinoma of the gallbladder. A clinicopathologic, histochemical, and immunohistochemical study of 21 patients with a poor prognosis,” Cancer, vol. 61, no. 9, pp. 1872–1879, 1988.

D. J. Friedman and W. E. Wheeler, “Cancer of the gallbladder,” Southern Medical Journal, vol. 83, no. 4, pp. 485–486, 1990.

K. Nishihara and M. Tsuneyoshii, “Small-cell carcinoma of the gallbladder—a clinicopathological, immunohistochemical and flow cytometric study of 15 cases,” International Journal of Oncology, vol. 3, no. 5, pp. 901–908, 1993.

K. Nishihara, E. Nagai, M. Tsuneyoshi, and M. Nagashima, “Small-cell carcinoma combined with adenocarcinoma of the gallbladder: a case report with immunohistochemical and flow cytometric studies,” Archives of Pathology and Laboratory Medicine, vol. 118, no. 2, pp. 177–181, 1994.

Y. Mizukami, T. Nagashima, K. Ikuta et al., “Advanced endocrine cell carcinoma of the gallbladder: a patient with 12-year survival,” Hepato-Gastroenterology, vol. 45, no. 23, pp. 1462–1467, 1998.

S.-S. Chuang, C.-N. Lin, C.-H. Chu, and F.-F. Chen, “Small cell carcinoma of the gallbladder: report of two cases,” Pathology and Oncology Research, vol. 5, no. 3, pp. 235–238, 1999.

J. E. Lane, A. N. Walker, G. W. Ayers, J. L. Foster, and J. T. Williams, “Small-cell undifferentiated carcinoma of neuroendocrine type originating in the gallbladder,” Current Surgery, vol. 59, no. 5, pp. 495–497, 2002.

S. Piana, A. Cavazza, S. Corrado, I. Putrino, and G. Gardini, “Combined small cell carcinoma and clear cell carcinoma of the gallbladder: report of a case and review of the literature,” Pathology Research and Practice, vol. 198, no. 12, pp. 821–824, 2002.

P. Nau, J. Liu, M. Dillhoff, M. Forster, J. Hazey, and S. Melvin, “Two cases of small cell carcinoma of the gallbladder,” Case Reports in Medicine, vol. 2010, Article ID 453624, 4 pages, 2010.

A. O. Cavazzana, A. S. Fassina, M. Tollot, and V. Ninfo, “Small-cell carcinoma of gallbladder. An immunocytochemical and ultrastructural study,” Pathology Research and Practice, vol. 187, no. 4, pp. 472–476, 1991.

Y. Iida and Y. Tsutsumi, “Small cell (endocrine cell) carcinoma of the gallbladder with squamous and adenocarcinomatous components,” Acta Pathologica Japonica, vol. 42, no. 2, pp. 119–125, 1992.

I.-G. Ron, N. Wigler, B. Ilie, and S. Chaitchik, “Small cell carcinoma of the gallbladder: clinical course and response to chemotherapy,” Tumori, vol. 78, no. 3, pp. 207–210, 1992.

O. I. Muraina, R. Tank, C. Dhingra et al., “Small cell carcinoma of gallbladder: report of two cases,” American Journal of Gastroenterology, vol. 91, no. 4, pp. 792–794, 1996.

H. Kuwabara and H. Uda, “Small cell carcinoma of the gall-bladder with intestinal metaplastic epithelium,” Pathology International, vol. 48, no. 4, pp. 303–306, 1998.

T. L. Moskal, P. J. Zhang, and H. R. Nava, “Small cell carcinoma of the gallbladder,” Journal of Surgical Oncology, vol. 70, no. 1, pp. 54–59, 1999.

K. Pavithran, D. C. Doval, A. K. Vaid, and R. N. Verma, “Small cell carcinoma of the gall bladder: case report and review of literature,” Tropical Gastroenterology, vol. 22, no. 3, pp. 170–171, 2001.

V. Bhutani, U. Dutta, B. Nagi, R. Nijhawan, and K. Singh, “Endocrine cell carcinoma of gall bladder,” Indian Journal of Gastroenterology, vol. 20, no. 3, pp. 109–110, 2001.

S. Bahadur, A. Shaukat, J. Gibbs et al., “Cisplatin and gemcitabine for small cell carcinoma of the gall bladder,” American Journal of Clinical Oncology: Cancer Clinical Trials, vol. 28, no. 4, pp. 425–426, 2005.

K. Pavithran, K. Prabhash, D. Hazarika, and D. C. Doval, “Neuroendocrine carcinoma of gallbladder: report of 2 cases,” Hepatobiliary and Pancreatic Diseases International, vol. 4, no. 1, pp. 144–146, 2005.

S. R. Jun, J. M. Lee, J. K. Han, and B. I. Choi, “High-grade neuroendocrine carcinomas of the gallbladder and bile duct: report of four cases with pathological correlation,” Journal of Computer Assisted Tomography, vol. 30, no. 4, pp. 604–609, 2006.

H. Imai, S. Matsui, Y. Tokuyama, S. Osada, H. Tomita, and I. Yasuda, “Small cell carcinoma of the gallbladder successfully treated by surgery and adjuvant chemotherapy,” American Surgeon, vol. 74, no. 3, pp. 272–273, 2008.

H.-J. Duan, H. Ishigame, Z. Ishii, N. Itoh, and H. Shigematsu, “Small cell carcinoma of the gallbladder combined with adenocarcinoma,” Acta Pathologica Japonica, vol. 41, no. 11, pp. 841–846, 1991.

B. J. Roth, D. H. Johnson, L. H. Einhorn et al., “Randomized study of cyclophosphamide, doxorubicin, and vincristine versus etoposide and cisplatin versus alternation of these two regimens in extensive small-cell lung cancer: a phase III trial of the southeastern cancer study group,” Journal of Clinical Oncology, vol. 10, no. 2, pp. 282–291, 1992.

S. Sundstrøm, R. M. Bremnes, S. Kaasa et al., “Cisplatin and etoposide regimen is superior to cyclophosphamide, epirubicin, and vincristine regimen in small-cell lung cancer: results from a randomized phase III trial with 5 years' follow-up,” Journal of Clinical Oncology, vol. 20, no. 24, pp. 4665–4672, 2002.

A. T. Turrisi III, K. Kim, R. Blum et al., “Twice-daily compared with once-daily thoracic radiotherapy in limited small-cell lung cancer treated concurrently with cisplatin and etoposide,” The New England Journal of Medicine, vol. 340, no. 4, pp. 265–271, 1999.

D. V. Skarlos, E. Samantas, P. Kosmidis et al., “Randomized comparison of etoposide-cisplatin vs. etoposide-carboplatin and irradiation in small-cell lung cancer. A hellenic co-operative oncology group study,” Annals of Oncology, vol. 5, no. 7, pp. 601–607, 1994.

A. Z. Abidin, M. C. Garassino, R. Califano, A. Harle, and F. Blackhall, “Targeted therapies in small cell lung cancer: a review,” Therapeutic Advances in Medical Oncology, vol. 2, no. 1, pp. 25–37, 2010.

M. Joshi, A. Ayoola, and C. P. Belani, “Small-cell lung cancer: an update on targeted therapies,” Advances in Experimental Medicine and Biology, vol. 779, pp. 385–404, 2013.