Operational Experience of a Quality Assurance System for HPV DNA Chip Tests / 임상검사와정도관리

BACKGROUND: A new HPV DNA chip test for the infection of 22 HPV genotypes was recently developed in Korea. This test using PCR and hybridization is inherently vulnerable to contamination, and to subjective qualitative test judgment. Hence, it warrants rigorous quality assurance measures. The authors would like to share operational experiences of the guidelines developed at Catholic University Holy Family Hospital. METHODS: Our quality assurance system of HPV DNA chip test comprised external quality controls, inter-laboratory proficiency tests, and internal quality controls. For the external quality controls, we analyzed the results of four years of participation in the quality assurance program by the Korean Laboratory Medicine Quality Assurance Association. The inter-laboratory proficiency tests with BioMedLab were done by single blind tests using patients' samples showing negative, single and multiple infections. The internal quality control dealt with methods to prevent contamination, and with reproduction tests. RESULTS: The results from the external quality control revealed consistency with HPV-16 in 7 trials during 4 years. The inter-laboratory proficiency tests showed a 82% consistency rate, 10 cases of inconsistency showing positive or negative mismatches, and 8 cases of genotypic mismatches. The 10 mismatches were due to the weak laser power of the scanner used in BioMedLab. The genotypic contamination rate found in the internal quality control was 3.3%, and the contamination by HPV-35 with low incidence rate was often observed. The contamination was not easily eliminated by re-tests from hybridization, but 80% of it was removed when re-tested with the remaining samples. The fluorescence intensity was not reproducible nor provide quantitative or semi-quantitative information. CONCLUSIONS: For quality assurance regarding HPV DNA chip tests, we suggest the following be implemented: technical quality control to rule out the false-negative and false-positive during PCR and hybridization; scanner quality control to prevent reading errors; and inter-laboratory proficiency tests.

The efficacy of HPV DNA chip test in the atypical squamous cell of undetermined significance / 부인종양

OBJECTIVE: This study was performed to investigate the efficacy of DNA chip method for detecting and genotyping of human papillomavirus (HPV) and screening of high-grade CIN (cervical intraepithelial neoplasia) or invasive cancer in the patients with atypical squamous cells of undetermined significance (ASC-US). METHODS: This study was based on 131 cases to be revealed ASC-US by Pap smear for the cervical cancer screening from July 2004 to Octorber 2004. They were evaluated by HPV DNA chip test, Cervical colposcopy and directed biopsy, and cone biopsy. The results of type 16, 18, 31, 33, 35, 39, 45, 51, 52, 53, 54, 56, 58, 59, 66 and 68 in HPV DNA chip test were categorized as high risk HPV. We evaluate the detection rate of the high-grade CIN and invasive cancer by HPV DNA chip test. RESULTS: The incidence of high risk HPV DNA was 51.1% (67/131). Twelve of 131 (9.2%) were diagnosed as high-grade CIN or CIS on histology. The detection rate of high risk HPV DNA in high-grade CIN and invasive cancer was 83.3% (10/12). The detection rate of high risk HPV DNA was 36.0% (31/86) in normal or reactive, and 83.3% (10/12) in CIN II or above on histology. Higher the grade of biopsy, more the detection rate of high risk HPV DNA by HPV DNA chip test. CONCLUSION: The use of HPV DNA chip test in patients with ASC-US may be useful in detection of high-grade CIN or invasive cancer.