A randomised study of protracted venous infusion of 5-fluorouracil (5-FU) with or without bolus mitomycin C (MMC) in patients with carcinoma of unknown primary

Redefining cancer of unknown primary: Is precision medicine really shifting the paradigm?

The concept of Cancer of Unknown Primary (CUP) has evolved with the advent of medical oncology. CUP can be difficult to diagnose and represents 2 to 5% of new cancers, therefore not exceptionally rare. Within CUPs can be identified a subset of favourable prognosis tumours, however the vast majority of CUP patients belongs to a poor prognosis group. CUP features significant oncological challenges, such as unravelling biological and transversal issues, and most importantly, improving patient's outcomes. In that regard, CUP patients' outcomes regrettably showed minimal improvement for decades and CUP remains a cancer group of very poor prognosis. The biology of CUP has two main hypotheses. One is that CUP is a subgroup of a given primary cancer, where the primary is present but cannot be seen due to its small size. The other, the "true" CUP hypothesis, states that CUP share features that make them a specific entity, whatever their tissue of origin. A true biological signature has not yet been described, but chromosomal instability is a hallmark of poor prognosis CUP group. Precision oncology, despite achieving identifying the putative origin of the CUP, so far failed to globally improve outcomes of patients. Targeting molecular pathways based on molecular analysis in CUP management is under investigation. Immunotherapy has not shown ground-breaking results, to date. Accrual is also a crucial issue in CUP trials. Herein we review CUP history, biological features and remaining questions in CUP biology, the two main approaches of molecular oncology in CUP management, in order to draw perspectives in the enormous challenge of improving CUP patient outcomes.

Important Role of the Dihydrouracil/Uracil Ratio in Marked Interpatient Variations of Fluoropyrimidine Pharmacokinetics and Pharmacodynamics

Dihydropyrimidine dehydrogenase (DPD) deficiency in patients causes severe toxicities in 5-fluorouracil/floxuridine (5-FU/FUDR) treatments. To determine the plasma dihydrouracil/uracil ratio (DUUR) as a potential index for setting 5-FU/FUDR doses, the authors conducted a prospective study on the relationships of the DUUR with 5-FU/FUDR pharmacokinetic and pharmacodynamic parameters. Forty gestational trophoblastic tumor (GTT) patients were treated with 30 mg/kg of 5-FU or prodrug FUDR during a 10-day cycle. The pretreatment DUURs of the patients were determined prior to the treatments, and plasma 5-FU and FUDR concentrations on day 1 of the test cycle were measured to calculate the corresponding pharmacokinetic parameters. The absolute neutrophil count (ANC) and human chorionic gonadotrophins (HCG/beta-HCG) were recorded as the efficacy indexes. The correlation of the DUUR with pharmacokinetic parameters and efficacy indexes was analyzed to look for a relationship between individual doses (in milligrams) and the varied DUUR. Pretreatment DUUR was significantly correlated with the corresponding plasma AUC (r > 0.80, P < .01), the plasma drug clearance (r > 0.78, P < .01), the ANC (r > 0.76, P < 0.01), and the decrease of HCG/beta-HCG levels (r > 0.5, P < 0.01). In addition, the charts for setting 5-FU/FUDR doses were designed for further validation in clinical trials. These findings indicate the important roles of the DUUR in remarkable interpatient variations of fluoropyrimidine pharmacokinetics and pharmacodynamics and propose a better index for setting individual 5-FU/FUDR doses based on interpatient variations in DPD levels.

Evaluation of survival benefits by platinums and taxanes for an unfavourable subset of carcinoma of unknown primary: a systematic review and meta-analysis

Background:

Although chemotherapeutic regimens containing a taxane or platinum agent have been widely recommended for unfavourable carcinoma of unknown primary (CUP), no evidence exists for the superiority of any administered regimens. To date, the efficacy has been mostly assessed in the limited setting of phase II trials, and few attempts have been made to synthesise all available data for survival outcomes.

Methods:

Electronic databases were searched from 1980 to 2011. Survival results were combined for each pre-specified category of regimens using a random-effects model, and meta-regression models were used to adjust for heterogeneity in some known prognostic factors.

Results:

A total of 32 studies were included for meta-analysis. Tendency towards better survival outcome by platinums or taxanes was indicated. After adjustment for important prognostic factors, however, the difference between the platinum-based and non-platinum regimens became no longer significant. Survival benefits by the taxane-based regimens remained significant, with a prolonged median survival time of 1.52 months (P=0.03) and a higher 1-year survival rate of 6.25% (P=0.05), but the benefit did not sustain for 2 years.

Conclusion:

Although no effective therapies have been established, this meta-analysis helps to fill an important gap of evidence. However, caution should still be taken because of the potential unmeasured confounding.

Carcinomas of an unknown primary origin--diagnosis and treatment

Carcinomas of an unknown primary origin (CUP) account for 3-5% of all malignancies and are thus among the ten most-frequent cancers worldwide. Having a specific and unique phenotype of early and usually aggressive metastatic dissemination with no identifiable primary tumor, CUP are a challenge for physicians. The diagnostic workup of patients with CUP includes a careful clinical and extensive histopathological examination, as well as the use of imaging techniques. CUP can be divided into favorable and unfavorable subsets. Patients with unfavorable CUP subsets have a poor prognosis with a median survival of approximately 8 months; the optimal chemotherapy regimen for these patients remains to be determined. Although studies have focused on the introduction of new cytotoxic agents with broad-spectrum clinical activity (such as gemcitabine, irinotecan, and taxanes), no randomized trial has provided clear evidence of a survival benefit. Molecular targeted therapies that are approved for other solid tumors are now considered for the treatment of patients with CUP. Molecular diagnostic tools, such as DNA microarray analysis, could help in the search for 'lost' CUP origins. In this Review, we describe the clinical evaluation of patients with CUP, and discuss treatment strategies and outcomes of patients with various CUP subsets.

Unknown primary tumors

An unknown primary tumor (UPT) is defined by the presence of a metastatic cancer without a known primary site of origin despite a standardized diagnostic workup. Clinically, UPTs show rapid progression and early dissemination, with signs and symptoms related to the metastatic site. The molecular bases of their biology remain largely unknown, with no evidence as to whether they represent a distinct biological entity. Immunohistochemistry remain the best diagnostic tool in term of cost-effectiveness, but the time-consuming "algorithmic process" it relies on has led to the application of new molecular techniques for the identification of the primary site of UPTs. For example, several microarray or miRNA classifications of UPTs have been used, with an accuracy in the prediction of the primary site as high as 90%. It should be noted that validating a prediction of tissue origin is challenging in these patients, since most of them will never have a primary site identified. Moreover, prospective studies to determine whether selection of treatment options based on such profiling methods actually improves patient outcome are still missing. In the last few years functional imaging (i.e. FDG-PET/CT) has gained a main role in the detection of the site of origin of UPTs and is currently recommended by the European Association of Nuclear Medicine. However, despite recent refinements in the diagnostic workup, the site of origin of UPT often remains elusive. As a consequence, treatment of patients with UPT is still empirical and inadequate.

Phase II trials in patients with carcinoma of unknown primary: a pooled data analysis

BACKGROUND

The management of carcinoma of unknown primary site remains debatable. The literature data consists of about 29 phase-II studies investigating 38 regimens, providing a broad range of response rates (RR).

METHODS

We performed a pooled published data analysis to identify the factors influencing RR in these 29 studies.

RESULTS

In front-line treatment, the overall RR was 31% (430/1,380). At least nine factors significantly influenced the reported RR, excluding drugs under investigation, such as the impact factor of the journal, single-centre study, some eligibility criteria, central radiological review, sample size calculation based on statistical hypothesis and stratification. Two drugs seem to improve RR: cisplatin and doxorubicin. Two drugs seem to be associated with a worse RR: irinotecan and carboplatin.

CONCLUSIONS

This pooled data analysis illustrates that in a phase II trial setting, it is impossible to attribute the variation in RR solely to the modification of drugs under investigation.

Metastases in the Absence of a Primary Tumor: Advances in the Diagnosis and Treatment of CUP Syndrome

INTRODUCTION

The term cancer of unknown primary site (CUP) syndrome is used to describe malignancies in which a complete diagnostic work-up detects metastases in the absence of an identifiable primary tumor.

METHODS

Based on a selective literature review, national and international guidelines, and the experience of the "Arbeitskreis CUP-Syndrom der Arbeitsgemeinschaft Internistische Onkologie der Deutschen Krebsgesellschaft" (CUP Syndrome Committee of the Medical Oncology Joint Working Group of the German Cancer Society), developments in the diagnosis and treatment of CUP syndrome are reported.

RESULTS

Most patients diagnosed with CUP have an unfavorable prognosis, with a life expectancy of less than 12 months. Nevertheless, it is important to identify subsets of patients in whom specific treatment offers the chance of long-term survival or even full recovery.

DISCUSSION

Only rigorous further development of diagnostic tools and treatment protocols will enable an improvement of the poor prognosis of patients with CUP syndrome. Specific molecular treatment strategies have shown promising results.

Carcinoma of Unknown Primary - an Orphan Disease?

Carcinoma of unknown primary (CUP) is an intriguing clinical finding that is defined as biopsy-proven metastasis from a malignancy in the absence of an identifiable primary site after a complete clinical work-up. CUP is a relatively common clinical entity, accounting for approximately 3-5% of all cancer diagnoses, and consists of a heterogeneous group of tumors that have acquired the capacity to metastasize before the development of a clinically evident primary lesion. Notable advances have been made over the past years in the treatment of well-defined clinical subgroups of CUP, such as women with peritoneal carcinomatosis and young adults with poorly differentiated carcinomas of midline distribution, but for the majority of patients, the prognosis still remains poor. In this review, we highlight recent advances in the diagnosis and treatment of patients with CUP syndrome, and emphasize the importance of identifying several favorable subsets of CUP, amenable to specific treatment options. In addition, we will point out novel diagnostic and therapeutic approaches which will hopefully improve both our understanding and the prognosis of this more or less neglected disease.

Forty years experience of treating cancer of unknown primary

Cancer of unknown primary site (CUP) is not a rare tumour. It accounts as the seventh to eighth most frequently diagnosed cancer in a general medical oncology service. Since CUP is not a homogeneous disease and it consists of different favourable and unfavourable sub-sets, treatment of each clinicopathological entity requires a unique approach. The spectrum of therapeutic management includes both locoregional and systemic therapy and should intend to offer optimal benefit to favourable CUP patients and palliative care to unfavourable cases. This review article provides both a historical outline of CUP treatment as well as a helpful therapeutic guide to every oncologist who treats CUP patients.

A Clinical Review of the Investigation and Management of Carcinoma of Unknown Primary in a Single Cancer Network

AIMS

Carcinoma of unknown primary (CUP) is a common encounter in oncological practice and represents 2.0-6.0% of all invasive malignancies. Evidence to support particular therapeutic strategies in this patient population is scarce, and empirical therapies are frequently derived from research on patients where the primary tumour site is known.

MATERIALS AND METHODS

This retrospective study reviewed the management of all patients recorded to have a diagnosis of CUP in a single cancer centre over a period of 12 months. Health records were reviewed documenting the CUP subtype, the investigations carried out both in the referring cancer unit and subsequently at the cancer centre and the recommended treatment (type and regimen), together with survival. The outcomes were examined in respect to a number of prognostic factors. Statistical tests were considered significant at P < 0.05.

RESULTS

One hundred and sixty-six patients were recorded to have a diagnosis of CUP, representing 3.7% of all referrals to the cancer centre. The median age of patients was 68 years (range 32-94 years), and 52.0% were women. The three most common CUP subgroups were CUP-liver/multiple sites (25.0%), CUP-bone (21.0%) and CUP-brain (16.0%). The remaining subgroups occurred at frequencies of less than 10% each. Histological confirmation was only obtained in 55.0% of cases. Even within a single subtype, 41 patients with CUP-liver/multiple sites underwent a total of 19 different investigations before any treatment being given. Forty-seven (28.0%) patients received radiotherapy, 30 (18.0%) received chemotherapy and 58 (35.0%) received supportive care alone. Nine different 5-fluorouracil-containing regimens were used in 11 patients treated with chemotherapy for CUP-liver. The overall median survival for all patients was 4.0 months. Survival was better in patients with a good performance status (0-1) and absent liver metastases (median survival 15.0 months; 95% confidence interval 8.0-22.1) and those who received chemotherapy (median survival 13.0 months; 95% confidence interval 7.4-18.6). Multivariate analysis confirmed female gender (P = 0.006), a good performance status (0/1) (P < 0.0001) and absent liver metastases (P = 0.002) as favourable prognostic indicators.

CONCLUSIONS

The appropriate management of patients with CUP is unclear and this study revealed a high degree of variation in clinical practice. This area is in urgent need of clinical research to ensure that the treatment of CUP is evidence based. Until such time, clinical recommendations are suggested for the investigation and treatment of such patients. Therapeutic progress will be facilitated by designating a clinical lead for CUP in each clinical network.