Performance of the Matsumiya scoring system in cervical cancer patients with bone metastasis: an external validation study

Background Accurate prognostic prediction of survival in cervical cancer patients with bone metastasis is important for treatment planning. We aimed to externally validate the Matsumiya scoring system using external patient data. Methods We collected a retrospective cohort of patients with cervical cancer diagnosed with bone metastasis at Chiang Mai University Hospital from 1st January 2007 to 31st December 2016. The Matsumiya score was composed of 5 predictors, including the presence of extraskeletal metastasis, ECOG performance status, history of previous chemo- or radiotherapy, the presence of multiple bone metastasis, and bone metastasis-free interval < 12 months. Harrell’s C-statistics and score calibration plots were used to evaluate the score performance. We also reconstructed the development study to estimate apparent performance values for comparison during external validation. Results A total of 124 cervical cancer patients with bone metastasis were included in this study . The 13-, 26-, and 52-week survival probabilities in the validation study were 70.1%, 50.5%, and 25.7%, respectively. Several differences were identified between development and validation studies regarding clinical characteristics, case-mix, and predictor–outcome associations. Harrell’s C-statistics in the development and validation study were 0.714 and 0.567. The score showed poor agreement between the observed and the predicted survival probabilities in the validation study. Score reweighting and refitting showed only modest improvement in performance. Conclusion A prognostic scoring system by Matsumiya et al. performed poorly in our cohort of Thai cervical cancer patients with bone metastasis. We suggested that the score should be sufficiently updated before being used.