Overview of patient management and future directions in unknown primary carcinoma

Skeletal Metastases of Unknown Primary: Biological Landscape and Clinical Overview

Skeletal metastases of unknown primary (SMUP) represent a clinical challenge in dealing with patients diagnosed with bone metastases. Management of these patients has improved significantly in the past few years. however, it is fraught with a lack of evidence. While some patients have achieved impressive gains, a more systematic and tailored treatment is required. Nevertheless, in real-life practice, the outlook at the beginning of treatment for SMUP is decidedly somber. An incomplete translational relevance of pathological and clinical data on the mortality and morbidity rate has had unsatisfactory consequences for SMUP patients and their physicians. We examined several approaches to confront the available evidence; three key points emerged. The characterization of the SMUP biological profile is essential to driving clinical decisions by integrating genetic and molecular profiles into a multi-step diagnostic work-up. Nonetheless, a pragmatic investigation plan and therapy of SMUP cannot follow a single template; it must be adapted to different pathophysiological dynamics and coordinated with efforts of a systematic algorithm and high-quality data derived from statistically powered clinical trials. The discussion in this review points out that greater efforts are required to face the unmet needs present in SMUP patients in oncology.

Cancer of unknown primary-Epidemiological trends and relevance of comprehensive genomic profiling

Background

Cancer of unknown primary (CUP) is a distinct clinicopathological entity with poor prognosis, frequently resistant to chemotherapy. Comprehensive genomic profiling (CGP) by next‐generation sequencing potentially identifies novel treatment options for CUP patients. The objective of this study was to determine incidence and survival trends and to discuss the value of CGP in CUP patients.

Methods

Age‐standardized incidence rates (ASR) per 100 000 were calculated for 2935 CUP patients from 1981 to 2014 using cancer registry data of the canton of Zurich, Switzerland. Kaplan–Meier survival curves were estimated for sex, age, and histological groups. Cox proportional hazards regression models were used to estimate adjusted hazard ratios (HR). A literature review was conducted to assess the current use of CGP in CUP patients.

Results

ASR of CUP increased from 10.3 to 17.6 between 1981 and 1997 and decreased to 5.8/100 000 in 2014. Mean overall survival remained stable. Mortality was significantly lower for patients with squamous cell carcinoma (HR 0.48 [95% CI, 0.41‐0.57]) and neuroendocrine carcinoma (0.75 [0.63‐0.88]) and higher for unclassified neoplasms (1.25 [1.13‐1.66]) compared to adenocarcinomas. The literature review identified 10 studies using CGP of CUP tissue. Clinically relevant mutations were identified in up to 85% of CUP patients, of which 13%‐64% may benefit from currently available drugs.

Conclusions

CUP incidence decreased probably due to improved diagnostics, but mortality did not improve over the last 34 years. CGP testing may help to identify molecular signatures in CUP patients and enable targeted treatment.

ECOG is as independent predictor of the response to chemotherapy, overall survival and progression-free survival in carcinoma of unknown primary site

The aim of the present study was to determine whether age, gender, functional status, histology, tumor location, number of metastases, and levels of the tumor markers, lactate dehydrogenase (LDH) and albumin, are poor prognostic factors for the response to chemotherapy in patients with carcinoma of unknown primary site. A total of 149 patients diagnosed with carcinoma of unknown primary site that was histologically confirmed, and treated with chemotherapy in the Oncology Hospital, National Medical Center, ‘Century XXI’ IMSS, Mexico City, Mexico during the period between January 2002 to December 2009, were carefully selected for the present study. The analysis of 149 patients diagnosed with carcinoma of unknown primary site revealed that the liver was the organ with the highest frequency of metastases (33.5%). The objective response rates to chemotherapy were ~30.2%. Notably, ECOG was an important predictor of response to chemotherapy (P=0.008). The median progression-free survival was 7.1 months. Upon multivariate analysis, the Eastern Cooperative Oncology Group (ECOG) Scale of Performance Status was observed as an independent predictor of progression (P<0.0001). The median overall survival was 14.2 months. The ECOG was also an independent predictor of mortality (P<0.0001). In conclusion, the data from the present study have demonstrated that ECOG is an independent predictor of a poor response to chemotherapy, lower overall survival and progression-free survival in carcinoma of unknown primary site.

Genomic characterisation of two cancers of unknown primary cases supports a kidney cancer origin

Cancer of unknown primary (CUP) comprises of 3-5% of new cancer diagnoses in the USA. Diagnostic work up typically includes CT of the chest, abdomen and pelvis, and histopathological review of tissue specimens. These measures are neither sensitive nor specific in determining tissue of origin (ToO) of primary tumours and, therefore, are unable to guide therapy. We present two cases of CUP for which we utilised ultra-deep genomic sequencing to identify the candidate ToO and to propose treatment. Patient 1 presented with metastases involving the lung, lymph nodes and bone. Patient 2 presented with an acute pathological fracture of the T7 vertebral body and metastases involving the bone, lymph nodes and soft tissue. No primary renal mass was found. Sequencing revealed SETD2 and NF2 mutations, and heterozygous loss of the short arm of chromosome 3 (3p). Mutations in conjunction with clinicopathological features strongly support a diagnosis of renal cell carcinoma. Both patients initially responded to mTORC1 inhibition therapy.

Cancer of unknown primary sites: what radiologists need to know and what oncologists want to know

OBJECTIVE

In this article, we review the role of imaging in cancer of unknown primary site (CUP) diagnosis and management and the utility of immunohistochemistry, serum tumor markers, and molecular profiling in the optimized care of CUP patients.

CONCLUSION

With advances in imaging, pathology, and molecular medicine, the diagnosis and management of CUP have evolved into more personalized and site-specific therapies. A multidisciplinary integrated approach among oncologists, pathologists, and radiologists is extremely important.

Cancer of unknown primary site

Cancer of unknown primary site (CUP) is a well recognised clinical disorder, accounting for 3-5% of all malignant epithelial tumours. CUP is clinically characterised as an aggressive disease with early dissemination. Diagnostic approaches to identify the primary site include detailed histopathological examination with specific immunohistochemistry and radiological assessment. Gene-profiling microarray diagnosis has high sensitivity, but further prospective study is necessary to establish whether patients' outcomes are improved by its clinical use. Metastatic adenocarcinoma is the most common CUP histopathology (80%). CUP patients are divided into subsets of favourable (20%) and unfavourable (80%) prognosis. Favourable subsets are mostly given locoregional treatment or systemic platinum-based chemotherapy. Responses and survival are similar to those of patients with relevant known primary tumours. Patients in unfavourable subsets are treated with empirical chemotherapy based on combination regimens of platinum or taxane, but responses and survival are generally poor.

Role of definitive radiation therapy in carcinoma of unknown primary in the abdomen and pelvis

OBJECTIVES

Carcinoma of unknown primary (CUP) in the abdomen and pelvis is a heterogeneous group of cancers with no standard treatment. Considered by many to be incurable, these patients are often treated with chemotherapy alone. In this study, we determined the effectiveness of radiation therapy in combination with chemotherapy in patients with CUP in the abdomen and pelvis.

PATIENTS AND METHODS

Medical records were reviewed for 37 patients with CUP treated with radiation therapy for disease located in the soft tissues and/or nodal basins of the abdomen and pelvis at the University of Texas M.D. Anderson Cancer between 2002 and 2009. All patients underwent chemotherapy, either before or concurrent with radiation therapy. Patients were selected for radiation therapy on the basis of histologic type, disease extent, and prior therapy response. Twenty patients underwent definitive radiation therapy (defined as radiation therapy targeting all known disease sites with at least 45 Gy) and 17 patients underwent palliative radiation therapy. Only 6 patients had surgical resection of their disease. Patient and treatment characteristics were extracted and the endpoints of local disease control, progression-free survival (PFS), overall survival (OS), and treatment-related toxicity incidence were analyzed.

RESULTS

The 2-year PFS and OS rates for the entire cohort were 32% and 57%, respectively. However, in patients treated with definitive radiation therapy, the rates were 48% and 76%, and 7 patients lived more than 3 years after treatment with no evidence of disease progression. Nevertheless, radiation-associated toxicity was significant in this cohort, as 40% experienced Grade 2 or higher late toxicities.

CONCLUSIONS

The use of definitive radiation therapy should be considered in selected patients with CUP in the soft tissues or nodal basins of the abdomen and pelvis.

Evaluation of prognostic factors and the role of chemotherapy in unfavorable carcinoma of unknown primary site: a 10-year cohort study

BACKGROUND

Carcinoma of unknown primary site (CUP) has a poor prognosis and the prognostic factors in these patients are not well established. Furthermore, there are no selection criteria for patients who should benefit from chemotherapy.

METHODS

The medical records of 179 CUP patients who were treated at Taipei Veterans General Hospital from 2000 to 2009 were reviewed. Factors associated with survival were determined by Kaplan-Meier analysis. Differences between the groups with and without palliative chemotherapy were analyzed.

RESULTS

Univariate analysis revealed multiple prognostic factors, including performance status, lung metastasis, number of metastatic organs, serum albumin, corrected serum calcium, lactate dehydrogenase (LDH), sodium, and cholesterol levels, palliative chemotherapy, and white blood cell and lymphocyte counts. Multivariate analysis showed that performance status < 2, serum albumin level ≥ 3.5 g/dl, corrected serum calcium level < 10.7 mg/dl, single metastatic organ, and palliative chemotherapy were independent factors of better prognosis. Patients with better performance status, higher serum albumin, and lower serum LDH levels had significantly greater benefit from palliative chemotherapy.

CONCLUSIONS

Certain patients with unfavorable CUP will have better survival. Identification of patients with unfavorable CUP who could benefit from palliative chemotherapy warrants future prospective studies.

Gene-expression assays and personalized cancer care: tissue-of-origin test for cancer of unknown primary origin

Cancer of unknown primary (CUP) is one of the ten most frequently diagnosed cancers in developed countries and accounts for 3–5% of all new cancer cases. For all cancer management, chemotherapeutic regimens and targeted agents have increasingly become primary-site dependent over the last decade, and thus, accurate identification of the primary site is crucial for CUP patients. Histopathologic examination along with immunohistochemical studies and different imaging modalities are most often performed for this purpose, but still a significant number of patients remain with an unidentified primary. Recently, gene-expression profiling assays have emerged as alternative tests for tumor tissue of origin determination. It is expected that molecular determination of the origin in patients with CUP will aid in the determination of management strategies. It is thus possible that personalized treatment of CUP patients based on molecular classification could significantly improve patient outcomes.

MicroRNA profiling for the identification of cancers with unknown primary tissue-of-origin

Cancer of unknown primary (CUP) represents a common and important clinical problem. There is evidence that most CUPs are metastases of carcinomas whose primary site cannot be recognized. Driven by the hypothesis that the knowledge of primary cancer could improve patient's prognosis, we investigated microRNA expression profiling as a tool for identifying the tissue of origin of metastases. We assessed microRNA expression from 101 formalin-fixed, paraffin-embedded (FFPE) samples from primary cancers and metastasis samples by using a microarray platform. Forty samples representing ten different cancer types were used for defining a cancer-type-specific microRNA signature, which was used for predicting primary sites of metastatic cancers. A 47-miRNA signature was identified and used to estimate tissue-of-origin probabilities for each sample. Overall, accuracy reached 100% for primary cancers and 78% for metastases in our cohort of samples. When the signature was applied to an independent published dataset of 170 samples, accuracy remained high: correct prediction was found within the first two options in 86% of the metastasis cases (first prediction was correct in 68% of cases). This signature was also applied to predict 16 CUPs. In this group, first predictions exhibited probabilities higher than 90% in most of the cases. These results establish that FFPE samples can be used to reveal the tissue of origin of metastatic cancers by using microRNA expression profiling and suggest that the approach, if applied, could provide strong indications for CUPs, whose correct diagnosis is presently undefined.

Validation of a microRNA-based qRT-PCR test for accurate identification of tumor tissue origin

Identification of the tissue of origin of a tumor is vital to its management. Previous studies showed tissue-specific expression patterns of microRNA and suggested that microRNA profiling would be useful in addressing this diagnostic challenge. MicroRNAs are well preserved in formalin-fixed, paraffin-embedded (FFPE) samples, further supporting this approach. To develop a standardized assay for identification of the tissue origin of FFPE tumor samples, we used microarray data from 504 tumor samples to select a shortlist of 104 microRNA biomarker candidates. These 104 microRNAs were profiled by proprietary quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) on 356 FFPE tumor samples. A total of 48 microRNAs were chosen from this list of candidates and used to train a classifier. We developed a clinical test for the identification of the tumor tissue of origin based on a standardized protocol and defined the classification criteria. The test measures expression levels of 48 microRNAs by qRT-PCR, and predicts the tissue of origin among 25 possible classes, corresponding to 17 distinct tissues and organs. The biologically motivated classifier combines the predictions generated by a binary decision tree and K-nearest neighbors (KNN). The classifier was validated on an independent, blinded set of 204 FFPE tumor samples, including nearly 100 metastatic tumor samples. The test predictions correctly identified the reference diagnosis in 85% of the cases. In 66% of the cases the two algorithm predictions (tree and KNN) agreed on a single-tissue origin, which was identical to the reference diagnosis in 90% of cases. Thus, a qRT-PCR test based on the expression profile of 48 tissue-specific microRNAs allows accurate identification of the tumor tissue of origin.