A model to guide the management and decision of re-planning during radiotherapy for cervical cancer

BACKGROUND: To establish a model to predict whether re-planning is needed in the process of cervical cancer radiotherapy. METHODS: We collected the clinical indexes of 132 patients diagnosed with cervical cancer receiving concurrent chemotherapy and radiotherapy, including 33 factors about tumor markers [carcinoembryonic antigen (CEA), cancer antigen 125 (CA-125), squamous cell carcinoma antigen (SCC)], tumor volume, rectal volume, bladder volume, volumes receiving 30–50 Gy in organs-at-risk (OARs), and the maximum dose (Dmax) received by 1–2 cc in OARs. We established a multivariate model for re-planning evaluation via principal component analysis, and then verified the model based on the internal data. RESULTS: We identified the dose index (P1), tumor size index (P2), and volumes receiving 30–50 Gy in OARs and the tumor (P3) as the three most weighted factors of the re-planning model. We set the cut-off for the re-planning modification requirement at 1. The model was consistent with R = 0.12P1 + 0.21P2 + 0.31P3, and it performed accurately that area under the test set characteristics curve (AUC) =0.826]. CONCLUSIONS: Our proposed method can help to reduce image re-examination during treatment, decrease toxicities in OARs, shorten the radiotherapy course, lessen oncologists’ efforts, and save medical resources.