Total radiation dose and overall treatment time are predictive for tumor sterilization in cervical carcinoma treated with chemoradiation and pulsed-dose-rate brachytherapy

Background and purpose: Treatment of locally advanced cervical cancer involves multidisciplinary care using external beam radiotherapy, chemotherapy, brachytherapy, and surgery. We aimed to compare both tumor and treatment characteristics between patients with complete pathologic response (CR) and patients with residual disease (RD).

Patients and methods: This monocentric retrospective study included 40 consecutive patients, treated with external beam radiotherapy, pulsed-dose-rate brachytherapy, and completion surgery. Treatment planning was performed to obtain a cumulative D90 value for the intermediate-risk clinical target volume (CTV) ≥60 Gy(α/β=10). Different clinical and dosimetric parameters were analyzed and compared between patients with RD and those with CR.

Results: We observed 18 (45%) patients with CR and 22 (55%) patients with RD. In univariate analysis, patients with RD had a significantly longer overall treatment time than those with CR (59.5 vs. 53 days, p = 0.0321). The D90 value for the high-risk CTV (HR-CTV) was higher in the group with CR than in the group with RD (65.9 vs. 64.2 Gy(α/β=10); p = 0.0439). In multivariate analysis, overall treatment time remained the only predictive factor for CR (p = 0.033), even if the difference for D90 HR-CTV kept a trend toward significance (p = 0.057).

Conclusions: This study showed that tumor sterilization is significantly correlated with overall treatment time and probably with cumulative dose delivered to the HR-CTV. These results emphasize the attention that must be given to treatment organization and dosimetry optimization.