Extrapulmonary small cell carcinoma localized in lymph nodes: is it a different clinical entity?

Current Treatment Strategies and Future Directions for Extrapulmonary Neuroendocrine Carcinomas: A Review

Importance

Patients with extrapulmonary neuroendocrine carcinomas (EPNECs) receive essentially the same treatment as those with small cell lung cancer (SCLC) despite differences in origin, clinical course, and survival. This SCLC-based approach is attributable to the rarity of EPNECs, which impedes the use of randomized clinical trials. However, neuroendocrine carcinomas are becoming more common because of the increasing use of systemic cancer therapy for adenocarcinomas. This treatment can transdifferentiate certain adenocarcinomas into neuroendocrine carcinomas. In addition, the treatment landscape for SCLC is slowly changing, potentially impacting the treatment paradigms for EPNECs.

Observations

New information on tumorigenesis of EPNECs from different origins, either as a primary malignant tumor or after neuroendocrine differentiation from adenocarcinomas, demonstrates their biological similarity. Activated molecular pathways that appear to underlie the development of EPNECs are potentially targetable, and some of these targets, such as poly(adenosine diphosphate-ribose) polymerase, Wee1, and Aurora A kinase, are currently under investigation. Immune checkpoint inhibitors (ICIs) already constituted a new treatment modality for patients with SCLC and produced some promising results in patients with EPNECs.

Conclusions and Relevance

Although only moderately effective, the introduction of ICIs signifies the first new option in systemic treatment of SCLC in decades. To prove the value of ICIs and other new drugs for patients with EPNECs, these patients should be included in clinical trials independent of the primary tumor site. Furthermore, to optimize clinical decision-making for patients with EPNECs, experts from the neuroendocrine tumor board should collaborate with members from tumor site-specific boards, which will require patient referral to a center with EPNEC expertise.

KRAS Mutation in Small Cell Lung Carcinoma and Extrapulmonary Small Cell Cancer

BACKGROUND

Lung cancer is one of the most lethal cancers. It is mainly classified into 2 groups: non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). Extrapulmonary small cell carcinomas (EPSCC) are very rare. The Ras oncogene controls most of the cellular functions in the cell. Overall, 21.6% of human cancers contain a Kirsten Ras (KRAS) mutation. SCLC and EPSCC have several similar features but their clinical course is different.

AIMS

We investigated the KRAS mutation status in SCLC and EPSCC.

STUDY DESIGN

Mutation research.

METHODS

Thirty-seven SCLC and 15 EPSCC patients were included in the study. The pathological diagnoses were confirmed by a second pathologist. KRAS analysis was performed in our medical genetic department. DNA isolation was performed with primary tumor tissue using the QIAamp DNA FFPE Tissue kit (Qiagen; Hilden, Germany) in all patients. The therascreen KRAS Pyro Kit 24 V1 (Qiagen; Hilden, Germany) was used for KRAS analyses.

RESULTS

Thirty-four (91.9%) of the SCLC patients were male, while 11 (73.3%) of the EPSCC l patients were female. SCLC was more common in males, and EPSCC in females (p=0.001). A KRAS mutation was found in 6 (16.2%) if SCLC patients. The most common mutation was Q61R (CAA>CGA). Among the 15 EPSCC patients, 2 had a KRAS mutation (13.3%). When KRAS mutant and wild type patients were compared in the SCLC group, no difference was found for overall survival (p=0.6).

CONCLUSION

In previous studies, the incidence of KRAS mutation in SCLC was 1-3%; however, it was 16.2% in our study. Therefore, there may be ethnic and geographical differences in the KRAS mutations of SCLC. As a result, KRAS mutation should not be excluded in SCLC.

Extrapulmonary small cell carcinoma of lymph node: Pooled analysis of all reported cases

AIM

To study clinical outcomes and management of lymph nodes extrapulmonary small cell carcinoma (LNEPSCC).

METHODS

Herein, we perform a systematic search of published literature in the PubMed and EMBASE databases for studies describing LNEPSCC. For uniformity of reporting, LNEPSCC was staged as limited if it involved either single lymph node station or if surgery with curative intent had been undertaken. The disease was staged extensive if it involved two or more lymph node regions.

RESULTS

The systematic literature review yielded eight descriptions (n = 14) involving cervical, submandibular and inguinal lymph nodes. Eleven (64.7%) patients had limited disease (LD) and six (35.3%) had extensive disease (ED) at presentation. Chemotherapy (n = 6, 35.3%) or surgery (n = 4, 23.5%) were the most common form of treatment given to these patients. Complete response was achieved in 12 (70.6%) of the patients. Median (interquartile range) progression free survival and overall survival was 15 (7-42) mo and 22 (12.75-42) mo respectively. Of the three illustrative cases, two patients each had ED at presentation and achieved complete remission with platinum based combination chemotherapy.

CONCLUSION

LNEPSCC is a rare disease with less than 15 reported cases in world literature. Surgical resection with curative intent is feasible in those with LD while platinum based combination chemoradiation is associated with favorable outcomes in patients with ED. Prognosis of LNEPSCC is better than that of small cell lung cancer in general.

Extrapulmonary small cell carcinoma: the University of Kansas experience and review of literature

Though extrapulmonary small cell carcinoma was first described over 80 years ago, definitive treatment recommendations are lacking. The treatment strategies commonly utilized are extrapolated from pulmonary small cell carcinoma experience. A better understanding of this entity is needed to improve management approach. The University of Kansas tumor registry was reviewed from 1990 to 2013. Thirty-five cases met the inclusion and exclusion criteria for review. Age, gender, smoking status, weight loss, metastatic disease-related data, stage, performance status (PS), treatment received, and survival data were collected. Patients were evaluated with a variety of primary locations of disease including GI tract (29%), GU tract (35%), Gyn organs (17%), head and neck (14%), and unknown primary (9%). Several sites of metastatic disease were noted, with 57 and 43% of patients meeting criteria for limited disease (LD) and extensive disease (ED), respectively. Chemotherapy, surgery, and radiation were used in several different regimens, with small cell lung cancer-type regimens incorporating a platinum and etoposide being the most common (74%). Patients with LD had a median survival of 36 months compared with 5 months in patients with ED (p<0.0001). Among different primary sites, patients with GU and Gyn LD tumors had best median survival of 36 months. Among other variables that were examined with respect to their poor prognostic significance, PS>2 (p=0.001) and one or fewer number of treatment modalities especially in LD (p=0.0005) were found to be associated significantly with mortality. GI and GU tract tumors were the most common primary sites of disease in our retrospective review. Survival varied according to stage, PS, site of primary disease, use of chemotherapy, and number of treatment modalities used. Further studies are needed to better understand this rare disorder and optimize management approach.

Neuroendocrine carcinoma of unknown primary: a systematic review of the literature and a comparative study with other neuroendocrine tumors

INTRODUCTION

Neuroendocrine carcinomas of unknown primary (NCUP) represent a specific subset with relatively favorable prognosis. Data on biology, management and outcome of NCUP patients have not been systematically reviewed neither compared to those of neuroendocrine tumors of known primary.

PATIENTS AND METHODS

We systematically reviewed all publications studying neuroendocrine CUP patients and presented a single center retrospective patient series. In addition, we analyzed and specified the similarities and/or differences between NCUP and other neuroendocrine malignancies.

RESULTS

Five hundred patients with NCUP constituted a heterogeneous cohort in terms of histology, grade, anatomic site and tumor biology in published series and were managed mostly with platinum-based regimens. Among 294 patients with available outcome data, a median survival of 15.5 months (range 11.6-40) was observed. Comparative analysis with neuroendocrine solid tumors (NET) revealed that poorly-differentiated NCUP share an aggressive natural history and a dismal prognosis similar to high grade pulmonary and extrapulmonary neuroendocrine carcinomas (Large Cell Neuroendocrine bronchial Carcinomas, LCNEC and poorly differentiated gastroenteropancreatic tumors, GEP-NET). Well differentiated NCUP reveal a more indolent course with a survival range resembling that of typical and atypical pulmonary carcinoids, well differentiated gastrointestinal NETs and limited small cell lung carcinomas.

CONCLUSION

No evidence for distinct biology or outcome of NCUP patients emerged when histological grade was matched for known primary NETs. The high heterogeneity of the NCUP subgroup limits the potential for identification of reliable prognosticators and hinders development of novel targeted therapies.