Histologic transformation of rectal adenocarcinoma to choriocarcinoma after surgery and chemotherapy: A rare case report and review of the literature

INTRODUCTION AND IMPORTANCE

Choriocarcinoma is a rapidly progressive, widely metastatic, β-human chorionic gonadotropin (β-hCG)-secreting malignant tumor originating from trophoblast cells. Most choriocarcinomas are pregnancy-related. Choriocarcinoma of nonpregnant origin is very rare.

CASE PRESENTATION

A 60-year-old woman underwent abdominopelvic resection (APR) for low rectal cancer in May 2020. Postoperative pathological findings showed a poorly differentiated adenocarcinoma. Because of a post-operative recurrence, then she underwent chemotherapy for rectal adenocarcinoma. In February 2021, imaging finding showed metastases in her liver, both lungs and pelvis. Surprisingly, the β-hCG level was significantly elevated. A transvaginal pelvic tumor biopsy was performed and the pathology report was presented after discussions: choriocarcinoma differentiated carcinoma was considered, with no adenocarcinoma component detected. Then the patient underwent chemotherapy regimens for choriocarcinoma, which were initially effective but quickly became resistant. The patient died 8 months after the diagnosis of adenocarcinoma of the rectum transformed into choriocarcinoma.

CLINICAL DISCUSSION

The dedifferentiation of adenocarcinoma to choriocarcinoma is rarely diagnosed and the disease is often overlooked, leading to delays in diagnosis and treatment, documenting cases and their clinical outcomes is important for future research and to improve patient prognosis. Perhaps genomic assessment using next-generation sequencing (NGS) technology could help in diagnosis and guide therapeutic strategies.

CONCLUSION

We report a very rare case of non-pregnant choriocarcinoma transformed from primary rectal adenocarcinoma. Awareness of secondary biopsies in special cases and genetic testing based on the dynamics of the disease should be raised in clinical practice to better develop precise treatment plans.

Brief Report: Comprehensive Clinicogenomic Profiling of Small Cell Transformation From EGFR-Mutant NSCLC Informs Potential Therapeutic Targets

Introduction

NSCLC transformation to SCLC has been best characterized with EGFR-mutant NSCLC, with emerging case reports seen in ALK, RET, and KRAS-altered NSCLC. Previous reports revealed transformed SCLC from EGFR-mutant NSCLC portends very poor prognosis and lack effective treatment. Genomic analyses revealed TP53 and RB1 loss of function increase the risk of SCLC transformation. Little has been reported on the detailed clinicogenomic characteristics and potential therapeutic targets for this patient population.

Methods

In this study, we conducted a single-center retrospective analysis of clinical and genomic characteristics of patients with EGFR-mutant NSCLC transformed to SCLC. Demographic data, treatment course, and clinical molecular testing reports were extracted from electronic medical records. Kaplan-Meier analyses were used to estimate survival outcomes. Next generation sequencing-based assays was used to identify EGFR and co-occurring genetic alterations in tissue or plasma before and after SCLC transformation. Single-cell RNA sequencing (scRNA-seq) was performed on a patient-derived-xenograft model generated from a patient with EGFR-NSCLC transformed SCLC tumor.

Results

A total of 34 patients were identified in our study. Median age at initial diagnosis was 58, and median time to SCLC transformation was 24.2 months. 68% were female and 82% were never smokers. 79% of patients were diagnosed as stage IV disease, and over half had brain metastases at baseline. Median overall survival of the entire cohort was 38.3 months from initial diagnoses and 12.4 months from time of SCLC transformation. Most patients harbored EGFR exon19 deletions as opposed to exon21 L858R alteration. Continuing EGFR tyrosine kinase inhibitor post-transformation did not improve overall survival compared with those patients where tyrosine kinase inhibitor was stopped in our cohort. In the 20 paired pretransformed and post-transformed patient samples, statistically significant enrichment was seen with PIK3CA alterations (p = 0.04) post-transformation. Profiling of longitudinal liquid biopsy samples suggest emergence of SCLC genetic alterations before biopsy-proven SCLC, as shown by increasing variant allele frequency of TP53, RB1, PIK3CA alterations. ScRNA-seq revealed potential therapeutic targets including DLL3, CD276 (B7-H3) and PTK7 were widely expressed in transformed SCLC.

Conclusions

SCLC transformation is a potential treatment resistance mechanism in driver-mutant NSCLC. In our cohort of 34 EGFR-mutant NSCLC, poor prognosis was observed after SCLC transformation. Clinicogenomic analyses of paired and longitudinal samples identified genomic alterations emerging post-transformation and scRNA-seq reveal potential therapeutic targets in this population. Further studies are needed to rigorously validate biomarkers and therapeutic targets for this patient population.

Long-Term Efficacy of Immune Checkpoint Inhibitor for Squamous Cell Carcinoma Lesion Transformed From EGFR-Mutated Adenocarcinoma After Osimertinib Treatment: A Case Report

Histologic transformation is one of the mechanisms of resistance to EGFR tyrosine kinase inhibitor in patients with NSCLC with EGFR mutation. The transformation from adenocarcinoma to squamous cell carcinoma (SCC) has been recently recognized as a mechanism of resistance to osimertinib. The prognosis after transformation to SCC is considered to be poor, and the therapeutic strategy for these patients is unclear. Herein, we report a case of long-term response to pembrolizumab monotherapy for an SCC-transformed lesion in a patient with EGFR-mutated adenocarcinoma after osimertinib treatment. A 68-year-old man underwent right upper lobectomy and was diagnosed with lung adenocarcinoma, pathologic stage IIA, with EGFR L858R. Five years after the surgery, he was diagnosed with recurrence and administered osimertinib. Ten months after, biopsy for an enlarged subpleural lesion revealed SCC with EGFR L858R, leading to a diagnosis of histologic transformation. Notably, the programmed death-ligand 1 expression level of the transformed lesion was higher than that of the adenocarcinoma (90% versus <1%). The size of the SCC lesion had reduced with pembrolizumab monotherapy, and the reduction was maintained for over 47 months since transformation. Nevertheless, the original adenocarcinoma lesion progressed after pembrolizumab therapy and was controlled by other cytotoxic drugs and readministration of osimertinib. Immune checkpoint inhibitor therapy is generally ineffective against EGFR-mutated adenocarcinoma. Nevertheless, it may be promising for achieving a good prognosis when EGFR-mutated adenocarcinoma transforms to SCC after developing EGFR tyrosine kinase inhibitor resistance-particularly if the transformed lesion has high programmed death-ligand 1 expression.

Evaluation and Management of Disease Transformation in Waldenström Macroglobulinemia

Histologic transformation (HT) to diffuse large B-cell lymphoma occurs rarely in Waldenström macroglobulinemia, with higher incidence in MYD88 wild-type patients. HT is suspected clinically when rapidly enlarging lymph nodes, elevated lactate dehydrogenase levels, or extranodal disease occur. Histologic assessment is required for diagnosis. HT carries a worse prognosis compared with nontransformed Waldenström macroglobulinemia. A validated prognostic score based on three adverse risk factors stratifies three risk groups. The most common frontline treatment is chemoimmunotherapy, such as R-CHOP. Central nervous system prophylaxis should be considered if feasible and consolidation with autologous transplant should be discussed in fit patients responding to chemoimmunotherapy.

Risk Factors for and Outcomes of Follicular Lymphoma Histological Transformation at First Progression in the GALLIUM Study

BACKGROUND

Although advanced‑stage follicular lymphoma (FL) is considered incurable, survival has improved with the introduction of the anti-CD20 antibodies, rituximab (R) and obinutuzumab (G). However, FL can undergo histological transformation (HT) to a more aggressive disease, and a validated model for predicting HT risk is not yet available.

PATIENTS AND METHODS

We assessed HT incidence, risk factors and outcomes in the phase III, GALLIUM study evaluating R- or G-chemotherapy in patients with previously untreated, advanced-stage FL (ClinicalTrials.gov NCT01332968). HT rates were assessed by repeat tumour biopsy at disease progression or relapse, at the investigator's discretion.

RESULTS

Of 1202 patients enrolled, 315 (26.2%) experienced progressive disease; 46 (14.6%) had a biopsy at first progression, 40 of whom had biopsy-confirmed HT. HT risk factors were male sex (subdistribution hazard ratio [sHR], 2.21; 95% confidence interval [CI], 1.16-4.20), elevated baseline serum lactate dehydrogenase (sHR, 3.97; 95% CI, 2.03-7.76), and elevated baseline serum β₂-microglobulin (sHR, 1.96; 95% CI, 1.02-3.79). Patients with HT at first progression had poorer post-progression survival than those with relapsed FL (2-year rate: 55.9% vs. 83.1%). Relapse with HT occurred earlier than FL relapse (median time from randomisation: 0.8 vs. 2.3 years).

CONCLUSION

HT was a low-frequency event associated with poor survival outcomes in the GALLIUM study. Male sex and elevated baseline levels of serum LDH and B2M were significant risk factors for HT. Further research is required to develop validated prognostic indices for HT risk and guide treatment decisions.

Molecular subtypes of small cell lung cancer transformed from adenocarcinoma after EGFR tyrosine kinase inhibitor treatment

Background

A certain proportion of non-small cell lung cancer (NSCLC) with activating EGFR mutations showed resistance to tyrosine kinase inhibitors (TKIs) by transforming their histology into small cell lung cancer (SCLC). In this study, we evaluated the molecular characteristics of transformed SCLCs.

Methods

Eighteen SCLC tissue samples transformed after EGFR TKI treatment were used for the analysis. Immunohistochemistry was conducted to evaluate the molecular subtype using antibodies representative of the major transcriptional factor-based molecular subtypes, ASCL1 (SCLC-A), NEUROD1 (SCLC-N), POU2F3 (SCLC-P), and YAP1. Subtypes were categorized based on a predefined criteria.

Results

Among the study population (n=18), most of the patients were initially diagnosed with adenocarcinoma (n=17), and one patient was diagnosed with adenosquamous histology. Eight patients (44.4%) were never-smokers, and nine patients were women (50.0%). Staining of pre-transformation sample was conducted in six patients, and five of them showed no discernible expression for ASCL1, NEUROD1, or POU2F3. However, the proportion of molecular subtypes after SCLC transformation was predominantly SCLC-N (n=9, 50.0%), followed by SCLC-Triple Negative (SCLC-TN; n=5, 27.8%) and SCLC-A (n=4, 22.2%). The median overall survival from TKI initiation was longer in patients who transformed to SCLC-A (P=0.009) than in those who transformed to either SCLC-N or SCLC-TN. However, the overall survival difference since SCLC transformation was not significant (P=0.370).

Conclusions

In our series, SCLC-N subtype was prevalent in SCLC transformed after EGFR TKI treatment. In addition, overall survival and the time to SCLC transformation from the EGFR TKI treatment were longer in patients who transformed to the SCLC-A type. Large-scale data will be required to confirm our findings.

Primary refractory follicular lymphoma: a poor outcome entity with high risk of transformation to aggressive B cell lymphoma

BACKGROUND

Primary refractory (PREF) follicular lymphoma (FL) has a completely different clinical course from that of FL that responds to front-line treatments. In addition to having poor responses to salvage therapies, it seems that patients with PREF are at increased risk of histological transformation (HT). The Aristotle consortium presented the opportunity of investigating the risk of HT in a very large series of cases. Thus, we investigated the risk of HT in patients with PREF FL compared with that of responding patients or in stable disease and ultimately their outcome.

METHODS

Six thousand three hundred thirty-nine patients from the Aristotle database were included in the analysis. These patients had a histologically confirmed grade 1, 2 or 3a FL diagnosed between 1997 and 2013. The primary end-points were the cumulative incidence (CI) of HT at the first progression or relapse and the survival after transformation.

FINDINGS

The 5-year CI of HT among patients with PREF was 34% (95% confidence interval (CI): 27-43), whilst it was 7.1% (95% CI: 6.0-8.5) in the group of patients with partial response (PR) or stable disease (SD) (PR + SD) and 3.5% (95% CI: 3.0-4.2) in the group of patients achieving complete response (CR). The 5-year survival after relapse (SAR) was 33% (95% CI: 28-39) for the PREF group, 57% (95% CI 54-61) in patients with PR, 51% (95% CI 43-58) in the SD group after first-line therapy and 63% (95% CI: 66-72) in patients with CR after initial treatment (p-value <0.001). The 5-year SAR for those patients with PREF who developed HT was 21% (95% CI: 12-31), clearly diminished when compared with those patients with PREF who did not experience HT (38% [95% CI: 31-44]) (p-value = 0.001).

INTERPRETATION

Patients with PREF FL have a dismal outcome and an associated very high rate of HT that further worsens their poor prognosis.

Clinical Characteristics, Treatment and Evolution of Splenic and Nodal Marginal Zone Lymphomas-Retrospective and Multicentric Analysis of Portuguese Centers

INTRODUCTION

Treatment of Splenic (SMZL) and Nodal (NMZL) Marginal Zone Lymphoma is not consensual. Histologic transformation (HT) to aggressive lymphoma is a poorly understood event, with an unfavorable outcome.

OBJECTIVES

Describe the clinical characteristics, treatment, outcomes and incidence of HT.

METHODS

Characteristics of patients with SMZL and NMZL consecutively diagnosed in 8 Portuguese centers were retrospectively reviewed. Endpoints were overall survival (OS), time to first systemic treatment (TTFST), frequency of HT and time to transformation (TTT).

RESULTS

This study included 122 SMZL and 68 NMZL, most of them received systemic treatment: 55.4% and 76.5%, respectively. Splenectomy was performed in 58.7% of patients with SMZL. Different treatment protocols were used. OS or TTFST did not differ significantly according to treatments. Given the small sample size, no conclusion can be made concerning the role of Rituximab in the treatment of NMZL and SMZL based in these results. HT was documented in 18 patients, mainly in SMZL, with a cumulative incidence at 5 years of 4.2%. We confirmed that age is a prognostic factor.

CONCLUSION

Randomized prospective trials are needed to standardize treatment in MZL. Patients with HT did appear to have shorter OS in comparison with those who did not experience HT (OS 5 years of 68.4% vs. 80.4%), but the number of HT was too small to reach statistical significance.

Histologic Transformation in an Untreated Waldenstrom's Macroglobulinemia After 14 Years: Case Report and Review of the Literature

Waldenstrom's macroglobulinemia (WM) is an indolent B-cell non-Hodgkin lymphoma characterized by lymphoplasmacytic histology in the bone marrow with monoclonal IgM. Median survival can be in excess of 10 years. The 5-year cumulative incidence of death is low at about 10%. One-third of all-cause specific mortality is due to the lymphoma for which histologic transformation (HT) is rare. Here we present a case of a 60-year-old man with longstanding untreated WM, presenting with minimally symptomatic transformation to diffuse large B-cell lymphoma (DLBCL), with an accompanying review of the literature. Transformed WM, diagnosed greater than 5 years, has a reported survival period of 8 - 9 months. This case highlights that after a decade of continued stability in WM, not requiring treatment, an acute change in laboratory data with minimally progressive IgM levels, in the absence of B symptoms and clinical findings, may be the harbinger of transformation and at the time of diagnosis can have a rapidly deteriorating clinical course. In this case, the tripling of the lactate dehydrogenase (LDH) as the primary drastic change demonstrates the importance of the rapid increase in LDH as a singly reliable marker for HT. Late transformation has been borne out as a negative variable as the generally indolent course of WM is curtailed with the poor outcome in HT. Although MYD88 wildtype is a possible predictive factor for transformation, it is unclear if late transformation is clonally or non-clonally related and further molecular investigation is needed.

An Unusual Presentation of Aggressive Primary Invasive Adenocarcinoma of Lung

Bilateral diffuse infiltrates on chest imaging can present a diagnostic challenge due to a broader differential diagnosis which includes pulmonary and non-pulmonary causes. Malignancy is generally not considered under differential diagnosis at the time of initial presentation. Here we present a case of primary adenocarcinoma of lung manifesting as diffuse bilateral infiltrates on imaging. Our case is unique in regards to its acute presentation, rapid progression to respiratory failure, ultimately leading to the demise of the patient. This indicates the aggressive nature of this malignancy and its variable presentation, like male gender and young age, thus emphasizing the importance of entertaining malignancy in such presentations, especially if there is no response to conventional antibiotic therapy.

Excellent outcomes of transformed lymphomas in the rituximab era without autologous stem cell transplantation: an Australian, single-centre experience

BACKGROUND

Histologic transformation (HT) is an important event with adverse prognosis in the natural history of indolent lymphomas. There is minimal data on HT in the Australian setting.

AIM

To characterise patients with biopsy-proven HT and their outcomes identified at a tertiary Australian Hospital.

METHODS

All patients with biopsy-proven HT during a 15-year period (2002-2017) were included. Clinico-pathological data were systematically collected from review of patient records. Survival estimates were assessed by the Kaplan-Meier method and compared using the log-rank test. Associations between variables and clinical outcomes were evaluated using Cox's proportional hazards model.

RESULTS

A cohort of 45 patients was identified with a median age of 66 years and the majority (59%) having high-risk disease (Revised-International Prognostic Index score ≥ 3). R-CHOP induction was used in 69% with an overall response rate of 82% (complete response (CR), 75%). 61% of these induction-responders received consolidation, with autologous stem cell transplant (ASCT) performed in only 17% and rituximab maintenance given to 31%. With a median follow-up of 47 months (range: 4-136), the 5-year overall survival (OS) was 69% (95% CI: 52%, 81%). Chemotherapy-naivety at HT was associated with a superior rate of CR (84% vs. 54%, p = 0.057) and 5-year OS (82% vs. 46%, p = 0.012). Rituximab maintenance was associated with a durable progression-free survival in induction-responders.

CONCLUSIONS

Excellent OS was observed in this modern cohort of patients treated with rituximab-containing induction and low rate of consolidation by ASCT, particularly in those who were chemotherapy-naïve at HT. This article is protected by copyright. All rights reserved.

Follicular lymphoma transforming to DLBCL and reverting back to follicular lymphoma at relapse-a case report

BACKGROUND

Transformation of low-grade follicular lymphoma to high-grade diffuse large B cell lymphoma (DLBCL) is known. However, the opposite is not commonly reported. In this report, we present a case of follicular lymphoma that underwent transformation to DLBCL. Three years after treatment for histologic transformation, the patient presented again with low-grade follicular lymphoma at the same site which is unusual in the natural history of follicular lymphoma.

CASE PRESENTATION

A 50-year-old female patient presented to us with complaints of slowly progressing swelling in the neck on the left side for a duration of 1 year. Past history of the patient revealed a diagnosis of follicular lymphoma in 2004 for which the patient had taken prednisolone and chlorambucil. Details of staging were not available with the patient. After a complete work-up, she was diagnosed as DLBCL, stage IIIE. She was treated with 6 cycles of CHOP regimen. She had very good response to chemotherapy. However, she defaulted and was lost to follow-up. She presented again after 3 years with history of painless progressive swelling in the right side of the neck for the last 1 year. Examination revealed cervical lymph nodes and ascites. This time, a repeat biopsy and immunohistochemistry was suggestive of follicular lymphoma. In view of significant ascites, she was started on chemotherapy with CVP regimen. After 6 cycles, she has good partial response and resolution of ascites. She is currently on follow-up.

CONCLUSIONS

We have presented a case of FL that has transformed to DLBCL after 10 years of diagnosis. After HT, she was treated with CHOP chemotherapy and the patient relapsed again after 3 years with follicular lymphoma histology. This case highlights the unique and varied natural history of follicular lymphoma that may be attributed to different subclones of malignant cells that may have arisen from a common progenitor FL cell and differential effect of chemotherapy on these subclones.

Treatment of Histologic Transformation

Histologic transformation from follicular lymphoma to aggressive lymphoma historically had a poor prognosis. Routine use of anti-CD20 antibody rituximab has changed the landscape of follicular lymphoma (FL) such that outcomes are improved in select patients, similar to de-novo diffuse large B-cell lymphoma. Several biological and clinical biomarkers can predict risk of transformation, and ongoing research is improving understanding of the biology surrounding the transformation process. This review provides an overview of risk factors, prognosis, and treatment of histologic transformation of FL.

Histologic transformation of lung cancer during pembrolizumab therapy: A case report

Immune checkpoint inhibitors that block the programmed death 1/programmed death ligand 1 pathways are widely used to treat advanced lung cancers. There are seldom cases of histologic transformation reported after treatment with immunotherapy. Here, we report the case of a 69‐year‐old man with stage IV lung squamous cell carcinoma. He received pembrolizumab monotherapy and had a partial response. After 22 cycles of pembrolizumab, chest computed tomography (CT) showed a left hilar tumor, bilateral pleural effusion and lymphadenopathy. The cytology of pleural effusion and bronchoscopic biopsy of an intraluminal lesion revealed small cell lung cancer. After two cycles of chemotherapy (etoposide/carboplatin), CT scan revealed shrinkage of lesions. This is the first case of lung squamous cell carcinoma with histologic transformation after treatment with pembrolizumab alone.

Histologic transformation of t(11;18)-positive MALT lymphoma presented with aberrant T-cell marker expression

Mucosa-associated lymphoid tissue (MALT) lymphoma with t(11;18)(q21;q21), resulting in an API2-MALT1 fusion transcript, is reported to rarely transform into aggressive lymphoma. Here, we report the clinical course of a patient who experienced histologic transformation after 20 years' disease history of t(11;18)-positive MALT lymphoma. The patient suddenly developed a large intrapelvic mass and ascites with a rapid increase in lactate dehydrogenase. Cytology of the ascites detected large abnormal cells, and flow cytometric analysis revealed that the cells were positive for cytoplasmic CD3, CD4, and CD38, and partially positive for CD7, but negative for CD19 and CD20. Antigen receptor gene rearrangement analysis and in situ hybridization of the immunoglobulin light chains confirmed that the tumor cells were of B-cell lineage. Chromosomal analysis showed complex karyotypes with intraclonal variation, and in addition to t(11;18), t(8;14) and heterozygous loss of the TP53 were demonstrated. Although histological and phenotypic features were significantly altered from the original MALT lymphoma, the presence of t(11;18) led us to the diagnosis of histologic transformation of MALT lymphoma. Although transformation of t(11;18)-positive MALT lymphoma into aggressive lymphoma is extremely rare, it may occur, probably with additional genetic abnormalities such as cMYC rearrangement and/or the loss of TP53.

Histologic transformation of non-small-cell lung cancer in brain metastases

BACKGROUND

Treatment strategies differ substantially for small-cell lung cancer (SCLC), adenocarcinoma and squamous-cell cancer (SCC). Therefore, it is of important significance to identify histologic transformation. There are no reports on histologic transformation in brain metastases (BM) to date. The aim of this study was to analyze the histologic transformation in BM for the first time.

METHODS

Medical records were reviewed and patients with both resected BM and primary tumors were examined retrospectively. The histologic diagnosis was confirmed by H&E staining, and additional diagnostic immunohistochemical stains were performed at the discretion of the pathologists. Characteristics of histologic transformation in BM were analyzed.

RESULTS

3 of 24 patients (12.5%) with both resected BM and primary non-small-cell lung cancers (NSCLCs) had evidence of histologic transformation in BM. One case with SCC transformed to adenocarcinoma in brain, one case with adenocarcinoma transformed to SCLC, and another case with adenocarcinoma transformed to SCC. The three cases of histologic transformation were all spontaneous and had not tested gene status.

CONCLUSIONS

We disclosed the histologic transformation of NSCLC in BM at a frequency not as low as expected, and speculated it as an evolution promoted by intratumor heterogeneity, though it warrants further prospective multi-institution investigations with comprehensive molecular analysis. Our findings provided further impetus for surgery when the metastatic or recurrent lesion is resectable, and repeated pathologic evaluation to help tailor individualized treatment.

A Brief Report of Transformation From NSCLC to SCLC: Molecular and Therapeutic Characteristics

INTRODUCTION

Histologic transformation from NSCLC to SCLC is a mechanism of resistance in EGFR-mutant tumors but is also occasionally observed in nonmutated NSCLC.

METHODS

We performed a multicenter retrospective collection of cases presenting between 2005 and 2017. The objectives were to analyze survival data and to define epidemiologic, clinical, treatment and histomolecular characteristics at both the time of diagnosis of NSCLC and of SCLC.

RESULTS

Forty-eight EGFR-mutant NSCLC and 13 non-EGFR-mutant cases were registered. Most EGFR-mutant tumors retained the same EGFR mutation after transformation. The median time to SCLC transformation was shorter in the EGFR-mutant group than in non-EFGR mutants (16 months versus 26 months (p = 0.01)). Both tumors were responsive to platinum etoposide regimens (45% partial response for the EGFR-mutant group versus 40% for non-EFGR mutants). The median overall survival rates were 28 months in the EGFR-mutant group versus 37 months in the non-EFGR-mutant group, respectively. After transformation, the median overall survival was 9 months in the non-EGFR-mutant group versus 10 months in the EGFR-mutant group.

CONCLUSIONS

Transformation into SCLC seems to occur more quickly in EGFR mutated tumors; however, once the tumor is transformed its survival and response to treatment seems comparable to that of classical SCLC.

Therapy escape mechanisms in the malignant prostate

Androgen receptor (AR) is the main target for prostate cancer therapy. Clinical approaches for AR inactivation include chemical castration, inhibition of androgen synthesis and AR antagonists (anti-androgens). However, treatment resistance occurs for which an important number of therapy escape mechanisms have been identified. Herein, we summarise the current knowledge of molecular mechanisms underlying therapy resistance in prostate cancer. Moreover, the tumour escape mechanisms are arranged into the concepts of target modification, bypass signalling, histologic transformation, cancer stem cells and miscellaneous mechanisms. This may help researchers to compare and understand same or similar concepts of therapy resistance in prostate cancer and other cancer types.