Microarray gene-expression profiling to predict lymph node metastasis in penile carcinoma

OBJECTIVE:
To determine the value of gene-expression profiling as a predictor of the status of the regional nodes in patients with penile carcinoma.

PATIENTS AND METHODS:
Tumour samples of 56 patients with penile squamous cell carcinoma were analysed for the gene expression on 35 k oligoarrays; 32 were from patients with histopathologically confirmed lymph node metastases and 24 from those with no lymph node involvement. The 56 patients were divided into a training and validation set. For the training set, 15 patients with histopathologically confirmed nodal metastases and 15 without were selected. The validation set consisted of the remaining 26 patients, containing 17 node-positive and nine with no nodal metastases.

RESULTS:
A 44-probe classifier had the best performance within the training set; this classifier correctly assigned 29 of 30 specimens in the training set to the two outcome groups. In the validation set of 26 tumours, the classifier correctly assigned 14 of the 26 (54%) specimens to the two outcome groups. Of the 17 specimens with histologically confirmed nodal involvement, 12 were classified as node-positive and five as node-negative, resulting in a sensitivity of 71%. Of the nine specimens from node-negative patients, two were correctly classified as node-negative and seven as node positive, resulting in a specificity of 22%.

CONCLUSIONS:
In this series, gene expression profiling did not produce a useful classifier to predict nodal involvement in patients with penile carcinoma.