Serum protein profile studies of cervical cancers in monitoring of tumor response to radiotherapy using HPLC-LIF: A pilot study

Objective: Exploration of the feasibility of serum protein profiles for monitoring tumor radioresponse in cervical cancers using HPLC-LIF system. Materials and methods: Twenty-one subjects were recruited in the study. Out of them 7 were healthy, 14 were cervical cancer patients who undertook fractionated radiotherapy (RT) with 2 Gy per fraction over 25 fractions, for 5 weeks followed by 2 applications of intracavitary brachytherapy once a week. Blood collected from above subjects was processed to obtain serum. Serum chromatograms of 'normal' (n=7) and conspicuous probes before RT (n=14, 'malignant') and 24 h after second fraction of RT (n=13, '2-RT'), were recorded using an In-house-built HPLC-LIF set-up. Data were analyzed in two approaches: (1) classical method using relative intensities of selected peaks, (2) principal component analysis (PCA). Clinical assessment of tumor radioresponse was carried out 4 months after first fraction of RT and the degree of the tumor shrinkage was determined as an index of radioresponsiveness (complete response (CR): 100% shrinkage, partial response (PR): ≥50% shrinkage, and no response (NR): ≤50% shrinkage) which was further correlated with the analysis of 2-RT serum chromatograms. Results: Normal vs. malignant chromatograms demonstrated pronounced differences in the 800-1800 s region. Malignant vs. 2-RT chromatograms showed minute variations in the 1300-1800 s region. Our analysis, in both of the approaches, produced clear differentiation between 'normal' and 'malignant', whereas differentiation between 'malignant' and '2-RT' was minimal. Clinical evaluation of the tumor radioresponse yielded that out of 13 patients (one patient discontinued the radiotherapy) ten showed CR, two showed PR and one NR. In case of prediction of tumor radioresponse, analysis of the 2-RT chromatograms produced only minor differentiation among CR, PR and NR groups. Conclusion: Protein profiling of serum samples differentiated 'normal' from 'malignant', but could not differentiate 'malignant' from '2-RT'. Also this technique has limited application in prediction of tumor radioresponse.