One size does not fit all for pancreatic cancers: A review on rare histologies and therapeutic approaches

Exocrine pancreatic neoplasms represent up to 95%of pancreatic cancers(PCs)and are widely recognized among the most lethal solid cancers,with a very poor 5-year survival rate of 5%-10%.The remaining<5%of PCs are neuroendocrine tumors that are usually characterized by a better prognosis,with a median overall survival of 3.6 years.The most common type of PC is pancreatic ductal adenocarcinoma(PDAC),which accounts for roughly 85%of all exocrine PCs.However up to 10%of exocrine PCs have rare histotypes,which are still poorly understood.These subtypes can be distinguished from PDAC in terms of pathology,imaging,clinical presentation and prognosis.Additionally,due to their rarity,any knowledge regarding these specific histotypes is mostly based on case reports and a small series of retrospective analyses.Therefore,treatment strategies are generally deduced from those used for PDAC,even if these patients are often excluded or not clearly represented in clinical trials for PDAC.For these reasons,it is essential to collect as much information as possible on the management of PC,as assimilating it with PDAC may lead to the potential mistreatment of these patients.Here,we report the most significant literature regarding the epidemiology,typical presentation,possible treatment strategies,and prognosis of the most relevant histotypes among rare PCs.

Metastatic clear cell sarcoma of the pancreas:A sporadic cancer

Primary or secondary clear cell sarcoma of the pancreas is an exceedingly rare and aggressive disease.In addition to pathology,molecular analysis is pivotal in differential diagnosis,especially with malignant melanoma.A key aspect in identifying clear cell sarcoma is specific genetic alterations,notably the translocation of t(12;22)(q13;q13),a diagnostic hallmark of this sarcoma subtype,which is absent in malignant melanoma.Treatment of primary clear cell sarcoma of the pancreas is the same as that for adenocarcinoma.

Challenges and opportunities in rare cancer research in China

Cancer is one of the major public health challenges in China.Rare cancers collectively account for a considerable proportion of all malignancies.The lack of awareness of rare cancers among healthcare professionals and the general public,the typically complex and delayed diagnosis,and limited access to clinical trials are key challenges.Recent years have witnessed an increase in funding for research related to rare cancers in China.In this review,we provide a comprehensive overview of rare cancers and summarize the status of research on rare cancers in China and overseas,including the trends of funding and publications.We also highlight the challenges and perspectives regarding rare cancers in China.

Efficacy of EGFR Tyrosine Kinase Inhibitors in Non-small Cell Lung Cancer Patients Harboring Different Types of EGFR Mutations:A Retrospective Analysis

With the development of molecular pathology, many types of epidermal growth factor receptor（EGFR） mutations have been identified. The efficacy of EGFR tyrosine kinase inhibitors（EGFR-TKIs） in non-small cell lung cancer（NSCLC） patients with different types of EGFR mutations, especially in patients with single rare mutations or complex mutations（co-occurrence of two or more different mutations）, has not been fully understood. This study aimed to examine the efficacy of EGFR-TKIs in NSCLC patients with different types of EGFR mutations. Clinical data of 809 NSCLC patients who harbored different types of EGFR mutations and treated from January 2012 to October 2016 at Renmin Hospital and Zhongnan Hospital, Wuhan, were retrospectively reviewed. The clinical characteristics of these patients and the efficacy of EGFR-TKIs were analyzed. Among these patients, 377 patients had only the EGFR del-19 mutation, 362 patients the EGFR L858R mutation in exon 21, 33 patients single rare mutations and 37 patients complex mutations. Among these 809 patients, 239 patients were treated with EGFR-TKIs. In all the 239 patients, the disease control rate（DCR） was 93.7% with two patients（0.2%） achieving complete response（CR）, the median progression free survival（PFS） was 13.0 months（95% confidence interval [CI], 11.6–14.4 months）, and the median overall survival（OS） was 55.0 months（95% CI, 26.3–83.7 months）. Subgroup analysis revealed that the DCR in patients harboring single rare or complex mutations of EGFR was significantly lower than in those with del-19 or L858 R mutation（P〈0.001）. Patients with classic mutations（del-19 and/or L858 R mutations） demonstrated longer PFS（P〈0.001） and OS（P=0.017） than those with uncommon mutations（single rare and/or complex mutations）. Furthermore, the patients with single rare mutations had shorter median OS than in those with other mutations. Multivariate Cox regression analysis identified that the type of EGFR mutations was an independent risk factor for PFS（hazard ratio [HR]=0.308, 95% CI, 0.191–0.494, P〈0.001） and OS（HR=0.221, 95% CI, 0.101–0.480, P〈0.001）. The results suggest that the single rare or complex EGFR mutations confer inferior efficacy of EGFR-TKIs treatment to the classic mutations. The prognosis of the single rare EGFR mutations is depressing. EGFR-TKIs may be not a good choice for NSCLC patients with single rare mutations of EGFR. Further studies in these patients with uncommon mutations（especially for the patients with single rare mutations） are needed to determine a better precision treatment.

Cholangiocarcinoma: a review of the literature and future directions in therapy

Cholangiocarcinomas (CCA) are a group of rare cancers with an incidence of about 1.26 per 100,000 people. The disease reflects one of three different subtypes: intrahepatic, perihilar or hilar and distal cholangiocarcinoma. The preferred modality of definitive therapy is surgical resection with or without adjuvant therapy, however the majority of patients with this disease do not present at an early stage. Some efforts to improve survival rates have come in the form of offering neoadjuvant therapy prior to surgical resection or liver transplantation. Some new protocols are in the process of development for neoadjuvant therapy. Despite advancements in locally advanced or borderline resectable lesions, most patient present at an advanced stage. The mainstay of treatment for advanced stage disease is chemotherapy regardless of location. The mainstay of treatment in fit patients is the combination of gemcitabine and cisplatin. The addition of nab-paclitaxel to this backbone is currently being evaluated in phase III trial. In addition, the role of targeted therapy is currently being studied extensively through multiple different mutational pathways including isocitrate dehydrogenase-1 (IDH1), fibroblast growth factor receptor (FGFR), epidermal growth factor receptor (EGFR) and ERBB2 (HER2/neu). CCA remains a significant challenge in medicine, however recent studies have shown that there is significant interest in advancing therapy in the form of neoadjuvant, adjuvant and palliative intent treatment.