Detection of human papillomavirus mRNA and cervical cancer cells in peripheral blood of cervical cancer patients with metastasis

Advanced technologies towards improved HPV diagnostics

Persistent infection with high-risk types of human papillomaviruses (HPV) is a major cause of cervical cancer, and an important factor in other malignancies, for example, head and neck cancer. Despite recent progress in screening and vaccination, the incidence and mortality are still relatively high, especially in low-income countries. The mortality and financial burden associated with the treatment could be decreased if a simple, rapid, and inexpensive technology for HPV testing becomes available, targeting individuals for further monitoring with increased risk of developing cancer. Commercial HPV tests available in the market are often relatively expensive, time-consuming, and require sophisticated instrumentation, which limits their more widespread utilization. To address these challenges, novel technologies are being implemented also for HPV diagnostics that include for example, isothermal amplification techniques, lateral flow assays, CRISPR-Cas-based systems, as well as microfluidics, paperfluidics and lab-on-a-chip devices, ideal for point-of-care testing in decentralized settings. In this review, we first evaluate current commercial HPV tests, followed by a description of advanced technologies, explanation of their principles, critical evaluation of their strengths and weaknesses, and suggestions for their possible implementation into medical diagnostics.

Differential microRNA Expression Analysis in Patients with HPV-Infected Ovarian Neoplasms

This study aimed to identify microRNAs (miRNAs) whose expression levels are altered by high-risk human papillomavirus (HR-HPV) infection in women with epithelial ovarian neoplasms. MiRNA expression was quantified by real-time polymerase chain reaction, while HR-HPV DNA was quantified using digital-droplet PCR. Analysis of 11 miRNAs demonstrated significantly lower hsa-miR-25-5p expression in HPV-infected compared to uninfected ovarian tissues (p = 0.0405), while differences in miRNA expression in corresponding serum were statistically insignificant. The expression of hsa-miR-218-5p in ovarian tumors was significantly higher in high-grade serous ovarian carcinoma (HGSOC) cases than in other neoplasms (p = 0.0166). In addition, hsa-miR-218-5p was significantly upregulated, whereas hsa-miR-191-5p was significantly downregulated in tissues with stage III/IV FIGO (p = 0.0009 and p = 0.0305, respectively). Using unsupervised clustering, we identified three unique patient groups with significantly varied frequencies of HPV16/18-positive samples and varied miRNA expression profiles. In multivariate analysis, high expression of hsa-miR-16-5p was an independent prognostic factor for poor overall survival (p = 0.0068). This preliminary analysis showed the changes in miRNA expression in ovarian neoplasms during HPV infection and those collected from HGSOCs or patients with advanced disease. This prospective study can provide new insights into the pathogenesis of ovarian neoplasms and host-virus interactions.

Liquid Biopsies: Emerging role and clinical applications in solid tumours

Late detection and lack of precision diagnostics are the major challenges in cancer prevention and management. Biomarker discovery in specific cancers, especially at the pre-invasive stage, is vital for early diagnosis, positive treatment response, and good disease prognosis. Traditional diagnostic measures require invasive procedures such as tissue excision using a needle, an endoscope, and/or surgical resection which can be unsafe, expensive, and painful. Additionally, the presence of comorbid conditions in individuals might render them ineligible for undertaking a tissue biopsy, and in some cases, it is difficult to access tumours depending on the site of occurrence. In this context, liquid biopsies are being explored for their clinical significance in solid malignancies management. These non-invasive or minimally invasive methods are being developed primarily for identification of biomarkers for early diagnosis and targeted therapeutics. In this review, we have summarised the use and importance of liquid biopsy as significant tool in diagnosis, prognosis prediction, and therapeutic development. We have also discussed the challenges that are encountered and future perspective.

HPV-Associated Breast Cancer: Myth or Fact?

Some estimates place the proportion of human malignancies attributable to viruses at between 15 and 20 percent. Viruses including the human papillomavirus are considered an interesting but controversial etiological risk factor for breast cancer. HPV infection is anticipated to be an early trigger in breast cancer carcinogenesis, followed by cumulative alterations over time ("hit and run" mechanism) through synergy with other environmental factors. The association between HPV and breast cancer has not yet been verified. There are very conflicting data on the presence of HPV DNA in breast cancer samples, and we lack a clarified, exact mode of HPV transmission to the breast. In our review article we analyzed the up-to-date knowledge about the association of HPV and breast cancer. Furthermore, we summarized the available original research published since 2010. In conclusion, the complexity and inconsistency of the available results together with the relatively low prevalence of HPV infection requires extensive research with much larger studies and exact and unified diagnostic methods are required to better understand the role of the HPV in breast carcinogenesis.

Presence of Human Papillomavirus DNA in Malignant Neoplasia and Non-Malignant Breast Disease

Breast cancer is the leading cause of cancer death among women worldwide. Multiple extrinsic and intrinsic factors are associated with this disease’s development. Various research groups worldwide have reported the presence of human papillomavirus (HPV) DNA in samples of malignant breast tumors. Although its role in mammary carcinogenesis is not fully understood, it is known that the HPV genome, once inserted into host cells, has oncogenic capabilities. The present study aimed to detect the presence of HPV DNA in 116 breast tissue biopsies and classify them according to their histology. It was found that 50.9% of the breast biopsies analyzed were malignant neoplasms, of which 74.6% were histologically classified as infiltrating ductal carcinoma. In biopsies with non-malignant breast disease, fibroadenoma was the most common benign neoplasm (39.1%). Detection of HPV DNA was performed through nested PCR using the external primer MY09/11 and the internal primer GP5+/6+. A hybridization assay genotyped HPV. HPV DNA was identified in 20.3% (12/59) of malignant neoplasms and 35% non-malignant breast disease (16/46). It was also detected in 27.3% (3/11) of breast tissue biopsies without alteration. However, there are no statistically significant differences between these groups and the existence of HPV DNA (p = 0.2521). Its presence was more frequent in non-malignant alterations than in malignant neoplasias. The most frequent genotypes in the HPV-positive samples were low-risk (LR) HPV-42 followed by high-risk (HR) HPV-31.

New Trends in the Detection of Gynecological Precancerous Lesions and Early-Stage Cancers

The prevention and early diagnostics of precancerous stages are key aspects of contemporary oncology. In cervical cancer, well-organized screening and vaccination programs, especially in developed countries, are responsible for the dramatic decline of invasive cancer incidence and mortality. Cytological screening has a long and successful history, and the ongoing implementation of HPV triage with increased sensitivity can further decrease mortality. On the other hand, endometrial and ovarian cancers are characterized by a poor accessibility to specimen collection, which represents a major complication for early diagnostics. Therefore, despite relatively promising data from evaluating the combined effects of genetic variants, population screening does not exist, and the implementation of new biomarkers is, thus, necessary. The introduction of various circulating biomarkers is of potential interest due to the considerable heterogeneity of cancer, as highlighted in this review, which focuses exclusively on the most common tumors of the genital tract, namely, cervical, endometrial, and ovarian cancers. However, it is clearly shown that these malignancies represent different entities that evolve in different ways, and it is therefore necessary to use different methods for their diagnosis and treatment.

Detection of Human Papillomavirus DNA in Paired Peripheral Blood and Cervix Samples in Patients with Cervical Lesions and Healthy Individuals

This study evaluated the presence of Human Papillomavirus (HPV) DNA in the cervix and peripheral blood of women with cervical intraepithelial neoplasia (CIN I, II, and III) and healthy individuals. Overall, 139 paired peripheral blood and cervix samples of healthy women and women with CIN I, II, and III (n = 68) were tested for HPV DNA by using standard procedures. Polymerase chain reaction (PCR) sequencing determined HPV types. Quantification of HPV16 E6 and E2 genes was performed to determine viral load and physical state. HPV DNA was detected in the cervix (21.1% in healthy individuals; 48.8–55.5% in CIN patients), blood (46.4% in healthy individuals; 44.1–77.7% in CIN patients) and paired peripheral blood and cervix samples (24% in healthy individuals; 32.5–44.4% in CIN patients). The most frequent types found in the cervix were HPV16, 18, 31, 33, 58, and 70, while HPV16, 18, 33, 58, and 66 were the most frequent types found in the blood. HPV DNA in the cervix was associated with previous sexually transmitted infections (STIs) (p = 0.023; OR: 2.978; CI:1.34–7.821), HPV DNA in the blood (p = 0.000; OR: 8.283; CI:3.700–18.540), and cervical lesions (CIN I/II or III) (p = 0.007). Binomial logistic regression showed that HPV DNA in the blood (p = 0.000; OR: 9.324; CI:3.612–24.072) and cervical lesions (p = 0.011; OR: 3.622; CI:1.338–9.806) were associated with HPV DNA in the cervix. However, we did not find an association between HPV DNA in the blood and cervical lesions (p = 0.385). Our results showed that only HPV DNA found in the cervix was associated with cervical lesions.

Liquid Biopsy in Cervical Cancer: Hopes and Pitfalls

Simple Summary

Cervical cancer is the fourth most common cancer in women worldwide, and its incidence is variably distributed between developed and less-resourced countries, in which socio-economic issues and religious beliefs often limit the widespread diffusion and the access to screening campaigns. In the “liquid biopsy” era, the application of non-invasive and repeatable techniques to the identification of diagnostic, prognostic, and predictive biomarkers might facilitate the management of this disease and, hopefully, improve its outcome. The purpose of this review is to explore the progress status of liquid biopsy in cervical cancer patients. Several methods are described, which include the analysis of circulating tumor cells, the search for pathogenic mutations on circulating tumor DNA, as well as the identification of circulating RNAs, focusing on their potential clinical applications and current limitations.

Abstract

Cervical cancer (CC) is the fourth most common cancer in women worldwide, with about 90% of cancer-related deaths occurring in developing countries. The geographical influence on disease evolution reflects differences in the prevalence of human papilloma virus (HPV) infection, which is the main cause of CC, as well as in the access and quality of services for CC prevention and diagnosis. At present, the most diffused screening and diagnostic tools for CC are Papanicolaou test and the more sensitive HPV-DNA test, even if both methods require gynecological practices whose acceptance relies on the woman’s cultural and religious background. An alternative (or complimentary) tool for CC screening, diagnosis, and follow-up might be represented by liquid biopsy. Here, we summarize the main methodologies developed in this context, including circulating tumor cell detection and isolation, cell tumor DNA sequencing, coding and non-coding RNA detection, and exosomal miRNA identification. Moreover, the pros and cons of each method are discussed, and their potential applications in diagnosis and prognosis of CC, as well as their role in treatment monitoring, are explored. In conclusion, it is evident that despite many advances obtained in this field, further effort is needed to validate and standardize the proposed methodologies before any clinical use.

Detection and quantitation of human papillomavirus DNA in peripheral blood mononuclear cells from blood donors

Human papillomavirus (HPV) is the etiological agent of cervical cancer. Also, HPV has been associated with anogenital cancer, oropharyngeal cancer, genital warts, and other dermatological diseases. HPV infects epithelial cells and their replication is closely linked to epithelial differentiation. The presence of HPV DNA in peripheral blood mononuclear cells (PBMC) has been reported in some patients with head and neck cancer, cervical cancer, and other genital diseases. However, the presence of HPV DNA in blood in asymptomatic subjects is still unresolved. The objective of this study was to evaluate the presence of HPV DNA in PBMC from asymptomatic blood donors. Blood samples were collected from 207 healthy Chilean blood donors. Genomic DNA was extracted from PBMC and HPV DNA detection was performed by real-time quantitative polymerase chain reaction assays with GP5+/6+ primers. HPV typing was carried out by genetic sequencing of a 140 to 150 bp fragment of the L1 gene. HPV DNA was detected in 6.8% (14/207) of blood donors. Single HPV infections were detected in seven blood donors. High-risk HPV was found in 6.3% (13/207) of cases: nine blood donors were infected with HPV-16, five with HPV-18, two with HPV-51, and one case was infected with either 32, 33, 45, 59, 66, 70, or 82. The median viral load value was 21.3 copies/mL blood or 13.4 HPV (+) cells per 10 ⁴ PBMC. These results show that HPV DNA is present in PBMC from healthy blood donors and it suggests that blood could be a new route of HPV dissemination.

[Circulating tumor DNA assessment for gynaecological cancers management]

Gynaecological cancers are frequent, with more than 16,000 cases per year in France for 6500 deaths. Few improvements in diagnostic methods, prognostic tools, and therapeutic strategies have occurred in the last two decades. Tumour genomic analyses from, at least in part, the Cancer Genome Atlas have identified some of the molecular alterations involved in gynaecological tumours growth and spreading. However, these data remain incomplete and have not led to dramatic changes in the clinical management of our patients. Moreover, they require invasive samples that are not suitable to objectives like screening/early diagnosis, assessment of treatment efficacy, monitoring of residual disease or early diagnosis of relapse. In the last years, the analysis of circulating tumour biomarkers (also called "liquid biopsies") based on tumour cells (circulating tumour cells) or tumour nucleotides (circulating DNA or RNA) has been massively explored through various indications, platforms, objectives; data related to circulating tumour DNA being the most important in terms of number of publications and interest for clinical practice. This review aims to describe the methods of analysis as well as the observations from the analysis of circulating tumour DNA in gynaecological tumours, from screening/early diagnosis to the adaptation of treatment for advanced stages, through choice of treatments and monitoring of subclinical disease.

Circulating tumor cells and cell-free nucleic acids in patients with gynecological malignancies

The ability to detect cancer cells in the blood or in the bone marrow offers invaluable information which potentially impacts early diagnosis, monitoring of treatment, and prognosis. Accessing blood or other body fluids has the additional advantage of being less invasive than biopsy. Consequently, considerable effort has been invested in the last 20 years in optimizing assays which may identify malignant cells at these anatomic sites. Detection of nucleic acids has been applied as alternative approach in this context, first targeting single cancer-associated genes using PCR-based technology, and recently using assays which identify different DNA classes, as well as microRNAs and exosomes. The present review focuses on studies which applied these assays to the detection of cells or cellular components originating from gynecological cancers.

Detection of circulating tumor cells in cervical cancer using a conditionally replicative adenovirus targeting telomerase-positive cells

Circulating tumor cells (CTC) are newly discovered biomarkers of cancers. Although many systems detect CTC, a gold standard has not yet been established. We analyzed CTC in uterine cervical cancer patients using an advanced version of conditionally replicative adenovirus targeting telomerase-positive cells, which was enabled to infect coxsackievirus-adenovirus receptor-negative cells and to reduce false-positive signals in myeloid cells. Blood samples from cervical cancer patients were hemolyzed and infected with the virus and then labeled with fluorescent anti-CD45 and anti-pan cytokeratin antibodies. GFP (+)/CD45 (-) cells were isolated and subjected to whole-genome amplification followed by polymerase chain reaction analysis of human papillomavirus (HPV) DNA. CTC were detected in 6 of 23 patients with cervical cancers (26.0%). Expression of CTC did not correlate with the stage of cancer or other clinicopathological factors. In 5 of the 6 CTC-positive cases, the same subtype of HPV DNA as that of the corresponding primary lesion was detected, indicating that the CTC originated from HPV-infected cancer cells. These CTC were all negative for cytokeratins. The CTC detected by our system were genetically confirmed. CTC derived from uterine cervical cancers had lost epithelial characteristics, indicating that epithelial marker-dependent systems do not have the capacity to detect these cells in cervical cancer patients.

Human papillomavirus and lung cancinogenesis: an overview

Lung cancer is the most common cause of cancer deaths worldwide. Although tobacco smoking is considered to be the main risk factor and the most well-established risk factor for lung cancer, a number of patients who do not smoke have developed this disease. This number varies between 15 % to over one-half of lung cancer cases, and the deaths from lung cancer in non-smokers are increasing every year. There are many other agents that are thought to be etiological, including diesel exhaust exposure, metals, radiation, radon, hormonal factors, cooking oil, air pollution and infectious diseases, such as human papillomavirus (HPV). Studies in various parts of the world have detected HPV DNA at different rates in lung tumors. However, the role of HPV in lung cancer is still unclear. Thus, in this review, we investigated some molecular mechanisms of HPV protein activity in host cells, the entry of HPV into lung tissue and the possible route used by the virus to reach the lung cells.

Presence of human papillomavirus in breast cancer and its association with prognostic factors

Breast cancer accounts for 16% of all female cancers worldwide, and in Venezuela, it is the leading cause of death among women. Recently, the presence of high-risk genotypes of human papillomavirus (HPV) has been demonstrated in breast cancer and has been associated with histopathological features of the tumours. In Venezuela, there is no study which determines the association between the presence of HPV in breast cancer and the histopathological features. The aim of this investigation is to evaluate the presence of HPV in the different types of breast cancer, according to their molecular classification, based on the expression of ER, PR, HER2 and Ki67. With this purpose in mind, we assessed the presence of the HPV genome in 24 breast cancer samples diagnosed with infiltrating ductal carcinoma, ductal carcinoma in situ (DCIS) and lobular carcinoma, by the INNO-LIPA genotyping extra kit and the evaluation of the markers ER, PR, HER2, and Ki67 by immunohistochemistry. The viral genome was found in 41.67% of the total number of samples, 51 being the most frequent genotype with 30.77%, followed by types 18 and 33, with 23.08%, respectively. Most tumours were found in the group of luminal A, with a low range of Ki67 expression. The presence of HPV in breast tumours could affect their growth pattern and metastatic power.

Association of HPV with genetic and epigenetic alterations in colorectal adenocarcinoma from Indian population

Several studies from developing countries have shown human papillomavirus to be associated with colorectal cancers, but the molecular characteristics of such cancers are poorly known. We studied the various genetic variations like microsatellite instability (MSI), oncogenic mutations and epigenetic deregulations like CpG island methylation in HPV associated and nonassociated colorectal cancer patients from Indian population. HPV DNA was detected by PCR using My09/My11 and Gp5+/Gp6+ consensus primers and typed using HPV16 and HPV18 specific primers. MSI was detected using BAT 25 and BAT 26 markers, and mutation of KRAS, TP53 and BRAF V600E were detected by direct sequencing. Methyl specific polymerase chain reaction (MSP) was used to determine promoter methylation of the classical CIMP panel markers (P16, hMLH1, MINT1, MINT2 and MINT31) and other tumour-related genes (DAPK, RASSF1, BRCA1 and GSTP1). HPV DNA was detected in 34/93 (36.5 %) colorectal tumour tissues, HPV 18 being the predominant high-risk type. MSI was detected in 7.5 % cases; KRAS codon 12, 13, BRAF V600E and TP53 mutations were detected in 36.5, 3.2 and 37.6 % of the cases, respectively. CIMP-high was observed in 44.08 % cases. HPV presence was not associated with age, stage or grade of tumours, MSI or mutations in KRAS, TP53 or BRAF genes. Higher methylation frequencies of all genes/loci under study except RASSF1, as well as significantly higher CIMP-high characteristics were observed in HPV positive tumours as compared to negative cases. HPV in association with genetic and epigenetic features might be a potent risk factor for colorectal cancer in Indian population.

Digital-Direct-RT-PCR: a sensitive and specific method for quantification of CTC in patients with cervical carcinoma

The detection of circulating tumour cells (CTC) in cancer patients may be useful for therapy monitoring and prediction of relapse. A sensitive assay based on HPV-oncogene transcripts which are highly specific for cervical cancer cells was established. The Digital-Direct-RT-PCR (DD-RT-PCR) combines Ficoll-separation, ThinPrep-fixation and one-step RT-PCR in a low-throughput digital-PCR format enabling the direct analysis and detection of individual CTC without RNA isolation. Experimental samples demonstrated a sensitivity of one HPV-positive cell in 500,000 HPV-negative cells. Spike-in experiments with down to 5 HPV-positive cells per millilitre EDTA-blood resulted in concordant positive results by PCR and immunocytochemistry. Blood samples from 3 of 10 CxCa patients each contained a single HPV-oncogene transcript expressing CTC among 5 to 15*10⁵ MNBC. Only 1 of 7 patients with local but 2 of 3 women with systemic disease had CTC. This highly sensitive DD-RT-PCR for the detection of CTC may also be applied to other tumour entities which express tumour-specific transcripts. Abbreviations: CTC – circulating tumour cells, CxCa – cervical cancer, DD-RT-PCR – Digital-Direct Reverse Transcriptase PCR, HPV – Human Papilloma Virus, MNBC – mononuclear blood cells, ICC – immunocytochemistry.

High-risk human papillomavirus (HPV) DNA sequences in metaplastic breast carcinomas of Mexican women

BACKGROUND

Metaplastic carcinoma, an uncommon subtype of breast cancer, is part of the spectrum of basal-like, triple receptor-negative breast carcinomas. The present study examined 20 surgical specimens of metaplastic breast carcinomas, for the presence of high-risk Human papillomavirus (HPV), which is suspected to be a potential carcinogenic agent for breast carcinoma.

METHODS

Mastectomy specimens from patients harboring metaplastic breast carcinoma, as defined by the World Health Organization (WHO), and who attended the Instituto Nacional de Cancerologia in Mexico City, were retrieved from the files of the Department of Pathology accumulated during a 16-year period (1995-2008). Demographic and clinical information was obtained from patients' medical records. DNA was extracted from formalin-fixed, paraffin-embedded tumors and HPV type-specific amplification was performed by means of Polymerase chain reaction (PCR). Quantitative Real-time (RT) PCR was conducted in HPV positive cases. Statistically, the association of continuous or categorical variables with HPV status was tested by the Student t, the Chi square, or Fisher's exact tests, as appropriate.

RESULTS

High-risk HPV DNA was detected in eight (40%) of 20 metaplastic breast carcinomas: seven (87.5%) HPV-16 and one (12.5%) HPV-18. Mean age of patients with HPV-positive cases was 49 years (range 24-72 years), the same as for HPV-negative cases (range, 30-73 years). There were not striking differences between HPV + and HPV- metaplastic carcinomas regarding clinical findings. Nearly all cases were negative for estrogen, progesterone and Human epidermal growth factor receptor 2 (HER2), but positive for Epidermal growth factor receptor (EGFR).

CONCLUSIONS

High-risk HPV has been strongly associated with conventional breast carcinomas, although the subtle mechanism of neoplastic transformation is poorly understood. In Mexican patients, the prevalence of HPV infection among metaplastic breast carcinomas is higher than in non-metaplastic ones, as so the HPV viral loads; notwithstanding, HPV viral loads show wide variation and remain even lower than cervical and other non-cervical carcinomas, making it difficult to assume that HPV could play a key role in breast carcinogenesis. Further studies are warranted to elucidate the meaning of the presence of high-risk HPVDNA in breast carcinomas.

PBMCs are additional sites of productive infection of bovine papillomavirus type 2

Bovine papillomavirus type 2 (BPV-2) is an oncogenic virus infecting both epithelial and mesenchymal cells. Its life cycle, similar to other papillomaviruses (PVs), appears to be linked to epithelial differentiation. Human and bovine PVs have been known to reside in a latent, episomal form in PBMCs; therefore, it is believed that blood cells, like all mesenchymal cells, function as non-permissive carriers. Here, for the first time in veterinary and comparative medicine, the BPV-2 E5 oncoprotein and the major structural L1 capsid protein, known to be expressed only in productive infections, were shown to occur in defined subsets of PBMCs. E5 oncoprotein was detected in sorted T- and B-cells as well as in monocytes by flow cytometry and Western blot analysis. However, CD4(+) and CD8(+) lymphocytes appeared to be the main circulating targets of the virus, thus possibly representing the most important reservoir of active BPV-2 in blood. L1 protein was identified by flow cytometry in a population of blood cells recognized as lymphocytes by morphological scatter properties. Western blot analysis was performed on lysates obtained from the sorted subpopulations of PBMCs and detected L1 protein in CD4(+) and CD8(+) cells only. Thus, this study showed that CD4(+) and CD8(+) lymphocytes are permissive for BPV-2 and are new, hitherto unknown sites of productive PV infection. In light of these observations, the life cycle of PVs needs to be revisited to gain novel insights into the epidemiology of BPV infection and the pathogenesis of related diseases.

Human papilloma virus and female lung adenocarcinoma

Lung cancer is the leading cause of cancer among women worldwide, and adenocarcinoma is the most common histological subtype among non-smoking women. Previous studies showed that human papillomavirus (HPV) infection may relate to the tumorigenesis of pulmonary adenocarcinoma. Women with anogenital malignancy have a higher risk of lung cancer, which raises the possibility of HPV transmission from the cervix to the lung. Two postulated pathways are discussed in this work. First, HPV may infect the female cervix and then move to the lung by blood circulation. The second transmission route is the HPV infection of oral cavity resulting from dangerous sexual contacts, and subsequently transmitted to the lung. This chapter also reviews the techniques for detecting the existence, subtypes, and viral load of HPV. Future studies are needed to demonstrate the causal inference between HPV infection and the risk of female lung adenocarcinoma.

Papillomavirus and disease in humans and animals

Papillomavirus (PV) induces exophytic lesions (papillomas, warts) and flat lesions (flat warts, cervical intraepithelial neoplasia) in cutaneous and mucosal epithelia. The lesions are usually benign and generally regress without eliciting any serious clinical problems in a host but occasionally persist. Persistent lesions can be debilitating and can also provide a focus for malignant transformation to squamous cell carcinoma, particularly in the presence of environmental or genetic cofactors. This has been experimentally demonstrated in animals, particularly in cattle, where bovine PV (BPV)-induced papillomas progress to cancer of the upper gastrointestinal (GI) tract and the urinary bladder in animals exposed to bracken fern in the pasture, and in rabbits, where the progression of skin papillomas to squamous cell carcinoma depends on a particular variant of cottontail rabbit PV (CRPV) and on the major histocompatibility complex (MHC) class II haplotype of the animal. In this review, various aspects of the biology of BPV and CRPV are described and compared with those of human PV, including viral genome structure, regulation of transcription of the viral oncogenes, function of the viral oncoproteins, co-operation between virus and cofactors, virus latency, immunity and vaccination.

Detection and quantitation of HPV 16 and 18 in plasma of Indian women with cervical cancer

OBJECTIVE

HPV infection is a necessary but insufficient cause of cervical cancer. The significance of HPV DNA in blood however is debatable because of variable detection rates due to the differences in the methodology used. The aim of this study was to detect and quantitate HPV 16 and 18 plasma viremia in women with cervical neoplasia.

METHODS

HPV DNA was detected in cervical tissue using consensus PGMY primers and genotyped using reverse line blot hybridization. HPV 16 and 18 quantitation in tissue and detection and quantitation in plasma was performed using sensitive real time PCRs targeting E6/E7 region of HPV 16/18 genome respectively. Results were correlated with viral loads in corresponding tissue and with clinical disease stage.

RESULTS

Viremia was detected in 56.4% of HPV 16 positive women and 20% of HPV 18 positive women. The prevalence of HPV 16 DNA in plasma increased with advancing disease stage (p=0.001), although HPV 16 absolute plasma viral load was not significantly associated with advancing disease stage (p=0.281). There was no correlation between absolute plasma viral load and viral load in corresponding cervical tissue (Spearman's rho=0.184, p=0.187). The prevalence of HPV 18 viremia and absolute HPV 18 plasma viral load were not associated with advancing disease stage (p=0.620, p=0.508).

CONCLUSION

The presence of HPV 16 in plasma is a marker of advancing cervical disease.

DETECTION OF DISSEMINATED TUMOR CELLS IN PERIPHERAL BLOOD

Metastases are the major cause of cancer-related deaths in patients with solid epithelial malignancies, such as breast, colorectal and prostate carcinomas. Hematogenous spreading of tumor cells from a primary tumor can be considered as a crucial step in the metastasis cascade leading eventually to the formation of clinically manifest metastases. Consequently, as shown in recent studies, the detection of disseminated tumor cells in peripheral blood might be of clinical relevance with respect to individual patient prognosis and staging or monitoring of therapy. However, the rarity of disseminated tumor cells in peripheral blood renders the application of sensitive techniques mandatory for their detection. The emergence of highly sophisticated reverse transciptase-polymerase chain reaction (RT-PCR) assays, combining a preanalytical enrichment step with the assessment of multiple molecular tumor markers expressed in disseminated tumor cells, provides a powerful tool in detecting disseminated tumor cells with high sensitivity and specificity. This review will discuss currently used tumor markers as well as experimental means to enhance the sensitivity and specificity of RT-PCR assays to detect disseminated tumor cells in the peripheral blood of patients with breast, colorectal, and prostate cancers, and their clinical relevance assessed in recent studies.

Detection of disseminated tumor cells in patients with gynecological cancers

OBJECTIVES

The presence of disseminated tumor cells (DTC) in breast cancer patients is associated with poor prognosis. However, there are limited data about the prevalence and prognostic impact of DTC in patients with gynecological tumors. The aim of this study was to evaluate the presence of DTC in the bone marrow (BM) of patients with gynecological cancers and to correlate their presence with established prognostic factors.

METHODS

BM aspirates of 201 patients with primary ovarian (n=69), cervical (n=54) and endometrial cancer (n=78), undergoing surgery at the Department of Gynecology and Obstetrics, University Hospital, Tuebingen, Germany between 1/2002 and 01/2006, were included into the study. Cytokeratin (CK)-positive cells were identified by immunocytochemistry using the pancytokeratin antibody A45B/B3.

RESULTS

The bone marrow positivity rate was 36% in ovarian, 26% in cervical and 17% in endometrial cancer, respectively. Presence of DTC was significantly correlated with FIGO (International Federation of Gynecology and Obstetrics) tumor stage (p<0.05). The recurrence rate was 14% in patients with CK-positive cells compared to 8% in CK-negative patients (p=0.2). There was no correlation between DTC and other established prognostic factors including nodal status or grading except for cervical cancer. Patients with positive lymph node status were more likely to be bone marrow positive compared to those with negative lymph node status (p<0.05).

CONCLUSIONS

Disseminated tumor cells seem to be a general phenomenon in epithelial tumors even though their clinical impact remains to be evaluated. The hypothesis that bone marrow is the homing site of disseminated tumor cells is further supported by these data since gynecological tumors only rarely metastasize to the skeletal system.

Could human papillomaviruses be spread through blood?

The human papillomaviruses (HPVs) are epitheliotropic viruses that require the environment of a differentiating squamous epithelium for their life cycle. HPV infection through abrasion of the skin or sexual intercourse causes benign warts and sometimes cancer. HPV DNA detected in the blood has been interpreted as having originated from metastasized cancer cells. The present study examined HPV DNA in banked, frozen peripheral blood mononuclear cells (PBMCs) from 57 U.S. human immunodeficiency virus (HIV)-infected pediatric patients collected between 1987 and 1996 and in fresh PBMCs from 19 healthy blood donors collected in 2002 to 2003. Eight patients and three blood donors were positive mostly for two subgroups of the HPV type 16 genome. The HPV genome detected in all 11 PBMC samples existed as an episomal form, albeit at a low DNA copy number. Among the eight patients, seven acquired HIV from transfusion (three associated with hemophilia) and one acquired HIV through vertical transmission; this patient also had received a transfusion before sampling. Our data suggest that PBMCs may be HPV carriers and might spread the virus through blood.

An association between human papillomavirus 16/18 deoxyribonucleic acid in peripheral blood with p16 protein expression in neoplastic cervical lesions

BACKGROUND

Human papillomavirus (HPV) infection plays a crucial role in cervical carcinogenesis. Apart from the detection of p16 protein in cervical tissues, the feasibility of the presence of HPV DNA in peripheral blood being an auxiliary marker of cervical lesions was examined.

METHODS

Peripheral blood samples and cervical tissues, from 36 cervical tissues from high-grade squamous intraepithelial lesions (HSIL) and 31 early invasive cervical cancers (EICC), were analyzed for HPV 16/18 DNA and HPV 16/18 E7 mRNA expression, as well as the in situ expressions of p16 and pRb to investigate the in-between associations.

RESULTS

The prevalence of HPV 16/18 DNA in patients with EICC was relatively higher than those of HSIL, in both of cervical tissues and peripheral blood. The presence of HPV 16/18 DNA in peripheral blood was positively correlated with that in cervical tissue, as well as with p16 overexpression in cervical tissues together with a significant correlation between E7 mRNA and pRb and p16 protein expressions.

DISCUSSION

A positive correlation between the presence of HPV 16 or 18 DNA in peripheral blood and p16 overexpression in tissues of patients with cervical lesions was confirmed. Together with p16 immunostaining in cervical tissues, the detection of high-risk HPV 16 or 18 DNA in peripheral blood may act as an auxiliary biomarker for HPV-associated neoplastic cervical lesions.

HPV DNA in plasma of patients with cervical carcinoma

BACKGROUND

HPV DNA has been detected in metastatic tumour and HPV plasma viraemia may indicate a poor prognosis and a high risk for metastasis.

OBJECTIVE

Detection of HPV DNA in plasma of patients with cervical carcinoma.

STUDY DESIGN

A cross-sectional study was done, wherein cervical biopsies and plasma samples were collected from 58 women with invasive cervical carcinoma, 10 women with cervical intraepithelial neoplasia (CIN) and 30 control women in the same age range. Polymerase chain reaction (PCR) was employed to detect the presence of HPV DNA. Samples positive for HPV DNA were typed by restriction fragment length polymorphism (RFLP). To confirm that the HPV sequence in plasma was identical to that in tissue, sequencing was done on all the paired plasma and tissue samples.

RESULTS

All the 30 paired cervical tissue and plasma samples from the controls were negative for HPV DNA. HPV DNA was detectable in cervical tissues of 55 (94.8%) of 58 patients with invasive cervical carcinoma and in all 10 patients (100%) with CIN and in eight (11.8%) of the total 68 plasma samples from patients. All eight plasma samples were from women with invasive cervical carcinoma with three each in stages IIIB and IV and one each in stages IIB and IB, respectively. Of the eight positive samples, seven were typed as HPV-16 and 1 as HPV-58. HPV types detected in cervical tissue and plasma pairs from these eight patients correlated as revealed by RFLP and sequencing. A patient with stage IB cancer had detectable HPV DNA in the external iliac lymph node, removed at Wertheims hysterectomy, which was histopathologically free of tumour. The HPV type in the node, was the same as that present in the paired tissue and plasma sample.

CONCLUSIONS

HPV DNA is detectable in the plasma of patients with advanced cervical cancer.

Detection of epidermal growth factor receptor mRNA in peripheral blood of cervical cancer patients

OBJECTIVE

Epidermal growth factor receptor (EGFR) has been reported to be expressed by immunohistochemistry in invasive cervical cancers. We evaluated the feasibility of detecting EGFR mRNA by EGFR-based reverse transcription polymerase chain reaction (RT-PCR) in peripheral blood of patients with cervical cancer.

METHODS

Expression of EGFR mRNA, cytokeratin (CK)-19 mRNA, and CK-20 mRNA was examined by RT-PCR in 12 human cervical cancer cell lines. All 12 cell lines expressed both EGFR mRNA and CK-19 mRNA, but only 4 of 12 (33.3%) cell lines expressed CK-20 mRNA. Peripheral blood samples from 20 healthy donors and 45 cervical cancer patients were also examined.

RESULTS

In peripheral blood from 20 healthy donors, neither EGFR mRNA nor CK-20 mRNA was expressed, but CK-19 mRNA was expressed in 13 of 20 (65%). In contrast, EGFR mRNA was expressed in 12 of 45 (26.7%) patients with cervical cancer (P = 0.0071, 2 test, patient vs control). On the other hand, expression of EGFR was observed in 98% of tumor tissues by immunohistochemistry. CK-19 mRNA and CK-20 mRNA were found in 35 of 45 (77.8%) and 0 of 45 (0%) patients, respectively (NS, chi(2) test, patient vs control). The rate of detection of EGFR mRNA in peripheral blood correlated with FIGO stage (P = 0.049).

CONCLUSION

Both CK-19 mRNA and CK-20 mRNA showed no diagnostic value as markers of circulating tumor cells in cervical cancers. However, EGFR mRNA in blood might be a useful marker of circulating tumor cells in cervical cancers.

Effect of blood transfusion during radiotherapy on the immune function of patients with cancer of the uterine cervix: role of interleukin-10

PURPOSE

To analyze prospectively the effects of blood transfusion administered during radiotherapy (RT) on the immune function of patients with locally advanced cervical cancer.

METHODS AND MATERIALS

In a total of 15 patients, 7 transfused and 8 untransfused, lymphocyte populations, including CD3+, CD4+, and CD8+ T-cell subsets, B cells (CD19+), and natural killer (NK) cells (CD56+, CD16+, CD3-) were studied before (i.e., time 0), during (i.e., times 1 and 2), and after (i.e., time 3) therapy. Expression of the early (CD25) and late (HLA-DR) activation markers on CD3+ T cells, the intracellular levels of perforin in CD8+ and CD56+ cells, and interferon (IFN)-gamma, interleukin (IL)-2, and IL-4 in CD4+ and CD8+ T cells were also measured. NK cell cytotoxicity against the NK-sensitive target K-562 cells and CD8+ T-cell-directed cytotoxicity against OKT3 hybridoma cells were also assessed. Finally, the plasma levels of the immunoregulatory cytokine IL-10 were analyzed by enzyme-linked immunosorbent assay.

RESULTS

The mean absolute number of all lymphocyte subsets compared with pretreatment levels decreased significantly during RT of both transfused and untransfused patients (p >0.001), with no detectable differences between the two groups in terms of total lymphocytes or relative numbers of CD3+ and CD4+ T cells, CD56+ NK cells, or CD19+ B cells. In contrast, concomitant with an inversion of the CD4/CD8 ratio, a significant increase in the number of CD8+ T cells at time 2 and CD3+ T cells, CD8+ T cells, and NK cells at time 3 was found in the transfused patients compared with the untransfused group. The percentages of CD25+/CD3+ T cells and HLA-DR+/CD3+ T cells increased during RT of the untransfused patients, but CD3+ T cells showed decreased CD25 expression and increased HLA-DR expression in the transfused group. An increase of CD8+ IFN-gamma+ T cells with a concomitant decrease in CD8+ IL-2+ T cells was found in the transfused vs. untransfused group, and no differences were noted in the percentage of CD4+ IFN-gamma+ T cells and CD4+ IL-2+ T cells. The proportion of perforin-positive CD8+ and CD56+ cells was higher in the transfused group than in the untransfused group. However, CD56+ cells and CD8+ T cells from the transfused patients showed markedly diminished cytotoxic function. Finally, IL-10 was detected only in the plasma of the transfused patients.

CONCLUSION

Blood transfusion during primary RT for cervical cancer profoundly alters the magnitude and characteristics of radiation-induced immunosuppression. Elevated serum IL-10 in transfused patients may play a role in the disregulation of lymphocyte function, in particular, the depression of NK- and T-cell cytotoxicity. Investigation of alternatives to blood transfusion during RT that do not diminish host immunity is warranted.

Detecting cytokeratin 19 mRNA in the peripheral blood cells of cervical cancer patients and its clinical-pathological correlation

OBJECTIVE

The aim of this study was to study the presence of cytokeratin 19 (CK19)-expressing cancer cells in the blood of preoperative patients with FIGO stage Ib and IIb cervical cancers who received radical hysterectomy and to investigate the cells' clinical significance.

METHODS

CK19 mRNA in the blood cells of the patients was detected preoperatively by a newly designed nested reverse transcriptase-polymerase chain reaction, which excluded pseudogenes a and b, performed on 84 patients with stage Ib and IIb cervical carcinoma. Possible correlations between clinicopathological factors were then analyzed.

RESULTS

The sensitivity of this assay was 1 CK19-mRNA-positive cell per 10(6) peripheral blood mononuclear cells. Results showed that 21.4% of the 84 patients with cervical carcinoma had CK19-mRNA-positive cells in the blood, in comparison with 5.7% of the 35 patients with benign gynecological tumors and 0% of the 28 healthy controls (P = 0.037 and 0.006, respectively). The positive tests in the cervical cancer patients were not associated with prognostic factors including stage, pelvic lymph node metastasis, pathological types, bulky tumor size (> or =4 cm), differentiation, parametrial extension, lymphovascular space involvement, deep stromal invasion, or age.

CONCLUSIONS

This study revealed the presence of circulating CK19-expressing cancer cells in the blood of patients with untreated early-stage cervical carcinomas, indicating that cervical cancer disseminated early. The survival effect of this phenomenon must be clarified. This detection assay provides an early checkpoint in the multistep process for developing metastasis in cervical cancer patients.

Evaluation of cytokeratin-19 mRNA as a tumor marker in the peripheral blood of nasopharyngeal carcinoma patients receiving concurrent chemoradiotherapy

The reverse transcriptase-polymerase chain reaction (RT-PCR) technique is a tool capable of detecting minute quantities of circulating tumor cell-derived transcripts. Nasopharyngeal carcinoma (NPC) is a rapidly growing tumor of epithelial origin and high metastatic potential. The aim of our study is to investigate the clinical value of circulating cytokeratin-19 (CK-19) mRNA detection in NPC patients. Between June 1997 and March 1999, 57 previously untreated, advanced NPC patients without distant metastasis were uniformly treated by concurrent chemoradiotherapy. Peripheral blood samples were collected prospectively before treatment and subjected to a nested RT-PCR assay. Measures were taken to prevent contamination and pseudogene interference. PCR products of positive results were verified by restriction enzyme Hae II and direct sequencing. Under our nested RT-PCR experimental conditions, 33.3% (19/57) clinically nonmetastatic NPC patients had CK-19 mRNA in their blood. The positive detection rates of CK-19 mRNA in the peripheral blood for different stages were 20.0% for stage II, 31.6% stage III and 43.5% stage IV (p = 0.1335). After a median follow-up time of 35 months, 2 patients had recurrences of their primary tumors and 14 developed distant metastases without locoregional recurrence. Nine of 19 (47.4%) CK-19 mRNA-positive patients and 5 of 38 (13.2%) CK-19 mRNA-negative patients developed distant metastasis (p = 0.00826). The 3-year metastasis-free survival rates were 49.9% for patients with detectable CK-19 and 85.9% for those with undetectable CK-19 (p = 0.0089, log-rank test). Our data suggest that the presence of CK-19 mRNA in the peripheral blood may be a potential marker of micrometastasis for NPC.

Detection of human papillomavirus DNA in primary and metastatic lesions of carcinoma of the cervix in women from Okinawa, Japan

Of 351 patients with invasive cervical cancer treated at Ryukyu University Hospital, Okinawa, 293 who were tested for human papilloma virus (HPV) DNA of the primary cervical lesion before the initiation of treatment were considered for the study. The polymerase chain reaction (PCR) was performed using fresh specimens, immediately after sampling. In 250 of 293 patients (85.3%), HPV DNA was detected in cervical tumor by PCR using L1 consensus primer. The positive rate by histology was 89.9% in squamous cell carcinoma, 93.8% in adenosquamous carcinoma, and 51.4% in adenocarcinoma. The former two figures were significantly higher than the latter (p < 0.001 and p = 0.002). Concerning identification of HPV types, HPV 16 was most predominant in squamous cell carcinoma, whereas type 18 was relatively high in adenocarcinoma. However, the type distribution of HPV was different to some extent from those in other countries. During treatment, 489 nodal and other tissue samples were obtained from 113 of 250 HPV DNA-positive patients, and were submitted to an assay of HPV DNA. HPV DNA was amplified in all 55 metastatic samples and also in 12 of 434 nonmetastatic tissues (2.8%). HPV types specified in these samples were always identical with the HPV types determined in their primary tumors. In 154 samples from 29 of 43 HPV DNA-negative patients, HPV DNA was not detected, either in 14 metastatic samples or in 140 histologically benign samples. Cancer-free, but HPV DNA-positive nodal, liver, and pulmonary tissues could be interpreted to be already involved at the time of examination, by observing the clinical course of the disease over time.

Human papillomavirus DNA in plasma of patients with cervical cancer

BACKGROUND

Human papillomavirus (HPV) is a crucial etiological factor for cervical cancer (CC) development. From a diagnostic view-point, the consistent presence of HPV in CC allows the viral DNA to be used as a genetic marker. The aims of this study were to evaluate the presence, physical status and clinical significant of HPV DNA in circulation of CC patients.

RESULTS

Whereas 6 out of 50 (12%) HPV positive CC patients revealed plasma HPV DNA, it was detected in none of 20 normal controls or 13 HPV negative CC cases. The plasma DNA exhibited an HPV type identical to the HPV in the primary tumors and the DNA from both sources was integrated into host genome. Interestingly, several findings suggested an association between plasma HPV DNA and metastasis. First, three of the HPV DNA positive cases were CC patients with clinical stage IVB or recurrence with distance metastases (P = 0.001, RR = 15.67). Second, the amount of plasma HPV DNA from metastatic patients to be three times more than three other patients without metastases. Finally, the later cases had tendency to develop recurrence distant metastases within one year after complete treatment when compared with other HPV associated CC patients with the same stage but without the present of plasma HPV DNA.

CONCLUSIONS

The plasma HPV DNA originated from the CC, was associated with metastasis and could be used as a marker representing the circulating free CC DNA.

Molecular quantification and mapping of lymph-node micrometastases in cervical cancer

BACKGROUND

A proportion of patients with cancer and lymph nodes negative on histology will develop recurrence. Reverse-transcriptase PCR (RT-PCR) is a highly sensitive method for detection of lymph-node micrometastases, but accurate quantitative assessment has been difficult.

METHODS

We studied primary tumours and 156 lymph nodes from 32 patients with cervical cancer (stage IA2, IB1, and IB2) and 32 lymph nodes from nine patients with benign disease. A fully quantitative, real-time RT-PCR assay was used to document absolute copy numbers of the epithelial marker cytokeratin 19. Primers and probe were designed not to amplify either of the two cytokeratin 19 pseudogenes.

FINDINGS

All primary tumours and histologically involved lymph nodes (six) had more than 106 copies of cytokeratin 19 mRNA per microg total RNA. Expression of cytokeratin 19 (up to 1.1 x 10(5) copies per microg RNA) was detected in 66 (44%) of 150 histologically uninvolved lymph nodes, and in nodes from 16 of 32 patients with cervical cancer. 15 of these 16 patients with evidence of micrometastases had the highest cytokeratin 19 transcription level in a first lymph-node drainage station (three obturator, six internal, and six external iliac node). Transcription of cytokeratin 19 was found at a low level in just one of 32 lymph nodes obtained from nine patients with benign disease. Median copy number of cytokeratin 19 transcription was significantly higher (>10(3) copies) in association with adverse prognostic features.

INTERPRETATION

The results suggest that about 50% of early-stage cervical cancers shed tumour cells to the pelvic lymph nodes. The amount of cytokeratin 19 expression was related to clinicopathological features. Further studies are required to document the clinical implications of molecular micrometastases.

Effects of concurrent cisplatinum administration during radiotherapy vs. radiotherapy alone on the immune function of patients with cancer of the uterine cervix

PURPOSE

To compare the effects of concurrent administration of cisplatinum (40 mg/m(2)/weekly) with radiation therapy (C-RT) to those induced by radiation therapy alone (RT) on the immune function of patients with locally advanced cervical cancer.

METHODS AND MATERIALS

In 8 prospectively randomized patients (i.e., 4 receiving RT vs. 4 receiving C-RT), lymphocyte populations including CD3+, CD4+ and CD8+ T-cell subsets, B cells (CD19+) and natural killer cells (CD56+, CD16+, CD3-) were studied before, during, and after therapy. Expression of the activation marker CD25 on CD3+ T cells, intracellular levels of perforin in CD8+ and CD56+ cells, and interferon-gamma (IFN-gamma) and IL-2 in CD4+ and CD8+ T cells was also measured. Finally, lymphoblast transformation and natural killer (NK) cytotoxic activity were assessed.

RESULTS

Both RT and C-RT significantly decreased the mean absolute number of all lymphocyte subsets compared to pretreatment levels (p > 0.001). However, no differences were detected in the characteristics or the magnitude of the lymphopenia induced by the two treatments. Both RT and C-RT increased similarly the percentages of CD25-positive lymphocytes (p > 0.001), and significantly decreased PHA-induced T-cell lymphoblast transformation (p > 0.001) and NK cytotoxic activity against K562 cells (p > 0.001). The percentage of perforin-positive and CD8+ T cells was not altered during either treatment, whereas the percentage of perforin-positive and CD56+ cells was significantly reduced during both treatments, and correlated with reduced cytotoxicity against K562 cells. The percentages of CD8+ IFN-gamma+ and CD4+ IFN-gamma+ T cells as well as that of CD8+ IL-2+ and CD4+ IL2+ T cells were not significantly altered by C-RT compared to RT alone. Finally, with both regimens, NK cells and B-cell numbers showed a more rapid recovery than T-cell numbers.

CONCLUSION

Administration of concurrent cisplatinum to radiation may synergistically increase cytotoxic effects of radiation on tumor cells but does not alter the magnitude and the characteristics of radiation-induced immunosuppression.

Utilization of polymerase chain reaction technology in the detection of solid tumors

BACKGROUND

Most cancer detection tests currently performed are based on either antibody assays to a marker protein with altered expression in cancer patients or on imaging studies to identify characteristic lesions. Generally, for a positive result, these detection assays require that a tumor have a significant volume of cancer cells. Advances in diagnostic techniques and technology may allow for cancer detection at earlier stages, when the tumor burden is smaller and potentially more curable. The molecular techniques of polymerase chain reaction (PCR) and reverse transcriptase PCR (RT-PCR) are highly sensitive methods for detecting a small number of cancer cells. Over the past few years, numerous clinical studies have used PCR techniques to detect physical alterations of genes, such as mutations, deletions, translocations and amplification, the presence of oncogenic viruses, and the expression of genes specific to tissue, cancer, and metastasis. The current status of PCR as a method for detecting marker genes in the management of solid tumors is reviewed.

METHODS

A review of the literature on the clinical utility of PCR and RT-PCR in the detection of solid tumor micrometastasis was conducted.

RESULTS

Amplification by PCR is a highly sensitive method to determine gene expression. A single cell expressing a tumor marker among 10-100 million lymphocytes can be detected by the PCR assay. This approach has been used to detect tumor cells in approximately 18 different solid tumor types, with melanoma and carcinoma of the breast and prostate the most widely investigated to date. PCR-based assays have been used to detect cancer cells in biopsies of solid tissue, lymph nodes, bone marrow, peripheral blood, and other body fluids. Several studies have reported a high specificity and sensitivity of tumor marker detection and a high correlation between PCR results and the presence of metastatic disease. However, in a few studies, PCR assays have not consistently demonstrated a higher sensitivity and specificity of detection than traditional modalities for many types of cancer. There has been a wide range in sensitivity and specificity among the studies, which may be partly attributed to the lack of uniformity among the PCR protocols used in different studies.

CONCLUSIONS

PCR can detect tumor marker-expressing cells that are otherwise undetectable by other means in patients with localized or metastatic cancer. Reports from various study groups have lacked uniformity in their protocols, and this has prevented adequate comparison. The clinical utility of this assay as a tool for the prognosis and management of cancer patients remains and area of active investigation. PCR is a powerful tool in the study of the biology of cancer metastasis and will likely serve as a useful adjunct to clinical decision-making in the future.

Utilization of polymerase chain reaction technology in the detection of solid tumors

BACKGROUND

Most cancer detection tests currently performed are based on either antibody assays to a marker protein with altered expression in cancer patients or on imaging studies to identify characteristic lesions. Generally, for a positive result, these detection assays require that a tumor have a significant volume of cancer cells. Advances in diagnostic techniques and technology may allow for cancer detection at earlier stages, when the tumor burden is smaller and potentially more curable. The molecular techniques of polymerase chain reaction (PCR) and reverse transcriptase PCR (RT-PCR) are highly sensitive methods for detecting a small number of cancer cells. Over the past few years, numerous clinical studies have used PCR techniques to detect physical alterations of genes, such as mutations, deletions, translocations and amplification, the presence of oncogenic viruses, and the expression of genes specific to tissue, cancer, and metastasis. The current status of PCR as a method for detecting marker genes in the management of solid tumors is reviewed.

METHODS

A review of the literature on the clinical utility of PCR and RT-PCR in the detection of solid tumor micrometastasis was conducted.

RESULTS

Amplification by PCR is a highly sensitive method to determine gene expression. A single cell expressing a tumor marker among 10-100 million lymphocytes can be detected by the PCR assay. This approach has been used to detect tumor cells in approximately 18 different solid tumor types, with melanoma and carcinoma of the breast and prostate the most widely investigated to date. PCR-based assays have been used to detect cancer cells in biopsies of solid tissue, lymph nodes, bone marrow, peripheral blood, and other body fluids. Several studies have reported a high specificity and sensitivity of tumor marker detection and a high correlation between PCR results and the presence of metastatic disease. However, in a few studies, PCR assays have not consistently demonstrated a higher sensitivity and specificity of detection than traditional modalities for many types of cancer. There has been a wide range in sensitivity and specificity among the studies, which may be partly attributed to the lack of uniformity among the PCR protocols used in different studies.

CONCLUSIONS

PCR can detect tumor marker-expressing cells that are otherwise undetectable by other means in patients with localized or metastatic cancer. Reports from various study groups have lacked uniformity in their protocols, and this has prevented adequate comparison. The clinical utility of this assay as a tool for the prognosis and management of cancer patients remains and area of active investigation. PCR is a powerful tool in the study of the biology of cancer metastasis and will likely serve as a useful adjunct to clinical decision-making in the future.