Clinical significance of micrometastatic cells detected by E48 (Ly-6D) reverse transcription-polymerase chain reaction in bone marrow of head and neck cancer patients.

PURPOSE: Despite improvements in locoregional treatment of head and neck squamous cell carcinoma (HNSCC), local and distant failure rates remain high. The strongest prognostic indicator of HNSCC is the presence of lymph node metastases in the neck, but the value of this indicator has limitations when using for the individual patient. The presence of micrometastatic cells in bone marrow has been shown to be a putative prognostic indicator in HNSCC and other epithelial malignancies, which might allow more accurate staging and selection of patients for whom adjuvant or experimental therapy is recommended. The gene encoding the E48 antigen is selectively expressed by HNSCC, and the detection of E48 transcripts in bone marrow by reverse transcription-polymerase chain reaction (RT-PCR) presumably represents the presence of micrometastatic cells. The purpose of this study was to determine the association between the presence of micrometastatic cells in bone marrow of HNSCC patients and clinical outcome. EXPERIMENTAL DESIGN: A total of 162 patients treated surgically for primary HNSCC underwent a single bone marrow aspiration from the upper iliac crest for detection of micrometastatic cells using E48 RT-PCR. In total, 139 patients were evaluable. The primary statistical endpoints were disease-free survival and distant metastasis-free survival. In addition, bone marrow samples of 30 noncancer controls were evaluated. RESULTS: E48 RT-PCR indicated the presence of micrometastatic cells in the bone marrow in 56 of 139 (40%) of the HNSCC patients and 0 of 30 of the noncancer controls (P < 0.0001). The presence of micrometastatic cells had no significant influence on disease-free survival or distant metastasis-free survival for the whole group of HNSCC patients (P = 0.1460 and P = 0.2912, respectively). For patients with >or=2 lymph node metastases, however, the presence of micrometastatic cells was associated with a poor distant metastasis-free survival (P = 0.0210). CONCLUSIONS: The presence of micrometastatic cells in bone marrow of HNSCC patients with >or=2 lymph node metastases is correlated with a poor distant metastasis-free survival. In this subgroup of HNSCC patients, E48 RT-PCR seems to be a valuable tool to identify patients who are at increased risk for development of distant metastases and therefore might benefit from experimental adjuvant systemic therapy.

Molecular diagnosis of surgical margins and local recurrence in head and neck cancer patients: a prospective study.

PURPOSE: Approximately 10-30% of surgically treated head and neck cancer patients develop local recurrences while the resection margins are histologically tumor free. These recurrences may arise from cancer cells left behind but not detected by the pathologist, or they may develop from precursor lesions adjacent to the tumor that were not completely resected. We have investigated whether TP53-mutated DNA in the surgical margins is suitable to identify patients with head and neck squamous cell carcinoma at risk for local and locoregional recurrence. EXPERIMENTAL DESIGN: In a prospective cohort study of 76 patients with histologically tumor-free margins, the presence of TP53-mutated DNA was determined in the surgical margins using the phage plaque assay and correlated to clinical outcome. Immunostaining of the molecular-positive margins for mutated p53 protein was used to identify whether unresected precursor lesions or residual tumor cells were left behind. RESULTS: The absence of TP53-mutated DNA in surgical margins was significantly associated with remaining free of local and locoregional recurrence (P = 0.027 and P = 0.028, respectively). Moreover, the presence of TP53-mutated DNA in the surgical margins was an independent prognosticator for locoregional recurrence (relative risk = 7.1; P = 0.021; 95% confidence interval, 0.9-56). In 20% of the cases, the presence of TP53-mutated DNA in the surgical margins was found to be related to the presence of tumor-related precursor lesions. CONCLUSIONS: This study shows the value of TP53-mutated DNA as a molecular marker to predict locally recurrent head and neck squamous cell carcinoma. The observation that all patients who were negative for TP53-mutated DNA in the surgical margins remained free of local recurrence raises hope that molecular analysis of histologically tumor-free surgical margins can be exploited to decide on postoperative radiotherapy. Furthermore, our data provide evidence that local recurrences originate mainly from tumor cells left behind but also originate, in part, from unresected precursor lesions.

Mutated p53 as a molecular marker for the diagnosis of head and neck cancer.

In total, 10-30% of patients with head and neck squamous cell carcinoma (HNSCC) develop local recurrences despite seemingly adequate tumour resection. This may result from minimal residual cancer (MRC): small numbers of tumour cells left behind in the surgical margins, undetectable by routine histopathology. In recent studies, p53 mutations have been considered as selective and sensitive DNA markers of cancer cells. There are two potential problems in using mutated-p53 DNA as a marker. Firstly, p53 mutations occur early in progression and might therefore detect unresected precursor lesions besides tumour cells. Secondly, DNA is a very stable biomolecule that might lead to false-positive results. These two potential problems have been evaluated in this study. Fifty patients with a radical tumour resection were included, of whom 30 showed a p53 mutation in the primary tumour. Histopathologically tumour-free surgical margins were quantitatively analysed for mutated p53 by molecular diagnosis (plaque assay) and subsequent (immuno)histopathology. p53 mutated DNA was detected in the surgical margins of 19/30 patients. Immunohistochemistry confirmed the presence of small tumour foci in 2/19 mutated p53-positive cases. In 7/19 cases, the tumour-specific p53 mutation was found in unresected dysplastic mucosal precursor lesions. Moreover, in a number of cases small p53-immunostained patches were detected, but the mutations found were never tumour-related. By screening contralateral exfoliated cells and plaque assays on RNA it was shown that detection of mutated-p53 DNA is prone to false-positive results. In conclusion, using p53 mutations as a marker, both MRC and unresected mutated p53-positive mucosal precursor lesions are detected within surgical margins. Molecular assessment of surgical margins using p53 mutations enables the selection of HNSCC patients at high risk for tumour recurrence, but tumour RNA seems at present to be a more specific biomolecule for analysis than tumour DNA.

Contribution of fibronectin-binding protein to pathogenesis of Streptococcus suis serotype 2.

In the present study we investigated the role of the fibronectin (FN)- and fibrinogen (FGN)-binding protein (FBPS) in the pathogenesis of Streptococcus suis serotype 2 in piglets. The complete gene encoding FBPS from S. suis serotype 2 was cloned in Escherichia coli and sequenced. The occurrence of the gene in various serotypes was analyzed by hybridization studies. The FBPS protein was expressed in E. coli and purified, and binding to human FN and FGN was demonstrated. The induction of antibodies in piglets was studied upon infection. An isogenic mutant unable to produce FBPS was constructed, and the levels of virulence of the wild-type and mutant strains were compared in a competitive infection model in young piglets. Organ cultures showed that FBPS was not required for colonization of the tonsils but that FBPS played a role in the colonization of the specific organs involved in an S. suis infection. Therefore, the FBPS mutant was considered as an attenuated mutant.