Impact of treatment time‐related factors on prognoses and radiation proctitis after definitive chemoradiotherapy for cervical cancer

This study aimed to investigate the impact of treatment time‐related factors on outcomes and radiation proctitis in patients undergoing concurrent chemoradiotherapy (CCRT) for cervical cancer. From September 2001 to December 2012, 146 patients with stage IIB cervical squamous cell carcinoma treated with CCRT were reviewed from a prospective cohort. Patients who received the same dose (45 Gy) of external beam radiation therapy (EBRT) were included in the analysis (n = 125). The same equivalent dose of 2 Gy (EQD2) of high‐dose‐rate intracavitary brachytherapy (HDR‐ICBT) was delivered at either 4 fractions of 6 Gy or 6 fractions of 4.5 Gy. The effects of the overall treatment time (OTT) and interval between EBRT and HDR‐ICBT on the cancer‐specific survival (CSS), local recurrence (LR), and incidence of proctitis were compared. The treatment time‐related factors did not adversely affect the CSS and LR rates. The multivariate analyses did not identify the OTT as an independent factor of CSS (P = 0.839) and LR (P = 0.856). However, OTT ≤56 days (P = 0.026) was identified as the only independent factor of overall proctitis. The 5‐year Grade 2 or greater proctitis rates were 14.9% and 0% (P = 0.001) in patients with the EBRT to ICBT interval ≤5 days and >5 days, respectively. To reduce rectal damage without compromising prognosis, the gap between EBRT and HDR‐ICBT should exceed 5 days in cervical cancer patients undergoing CCRT. Strictly limiting the OTT to 56 days may result in radiation proctitis without improvements in prognosis.