Diffusion-weighted magnetic resonance imaging in the early detection of response to chemoradiation in cervical cancer.

OBJECTIVE: To investigate diffusion-weighted magnetic resonance imaging (DWI) as an early and reproducible response indicator in women receiving concurrent radiotherapy and chemotherapy (chemoradiation) for advanced cervical cancer.
METHODS: Twenty women with advanced cervical cancer were included in a prospective cohort study. DWI was carried out prior to chemoradiation, repeated after 2 weeks of therapy and at the conclusion of therapy using a 1.5 T MRI scanner. The apparent diffusion coefficient (ADC) was calculated from the diffusion data at each assessment. This was correlated with final tumour response as determined by change in tumour size using MRI and conventional clinical response. Twelve women also underwent 2 separate pre-treatment DWI examinations to test for reproducibility of the ADC measurements.
RESULTS: ADC values after 2 weeks of therapy showed a significant correlation with eventual MR response (p=0.048, rho=0.448, Spearman's correlation) and clinical response (p=0.009, rho=0.568) as did the change in ADC after 2 weeks of therapy (p=0.01, rho=0.56 for MR response, p=0.03, rho=0.48 for clinical response). Reproducibility of ADC measurements was confirmed with a mean difference in ADC of -0.003 between consecutive pre-therapy MRI assessments and 95% confidence intervals of -0.12 and 0.11.
CONCLUSION: DWI has potential to provide a surrogate biomarker of treatment response in advanced cervical cancers. The use of ADC offers an early and reproducible indication of tumour response which may ultimately allow the development of individualised regimens.