Dosimetric parameters that predict late rectal complications after curative radiotherapy in patients with uterine cervical carcinoma

Tae Hyun Kim, Jinho Choi, Sung Yong Park, Seok Ho Lee, Kyu Chan Lee, Dae Sik Yang, Kyung Hwan Shin, Kwan Ho Cho, Hyun Sun Lim, Joo Young Kim

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Abstract

BACKGROUND. Late rectal complication (LRC) was a major late complication in patients with uterine cervical carcinoma who were treated with a combination of external beam radiotherapy (EBRT) and high-dose-rate intracavitary irradiation (HDR-ICR). For the current study, the authors retrospectively evaluated dosimetric parameters that were correlated with LRC ≥ Grade 2 in patients with uterine cervical carcinoma who were treated with curative radiotherapy, and they analyzed the appropriate dose estimates to the rectum that were predictive for LRC ≥ Grade 2. METHODS. Between July, 1994 and September, 2002, 157 patients who were diagnosed with Stage IB-IIIB cervical carcinoma and were treated with definitive radiotherapy were included. EBRT (41.4-66 grays [Gy] in 23-33 fractions) to the whole pelvis was delivered to all patients, with midline shielding performed after a 36-50.4 Gy external dose. HDR-ICR (21-39 Gy in 6-13 fractions to Point A) was administered at a rate of 2 fractions weekly after midline shielding of EBRT. LRC was scored using Radiation Therapy Oncology Group criteria. The total biologically effective dose (BED) at specific points, such as Point A (BEDPoint A), rectal point (BEDRP), and maximal rectal point (BEDMP), was determined by a summation of the EBRT and HDR-ICR components, in which the α/β ratio was set to 3. Analyzed parameters included patient age, tumor size, stage, concurrent chemotherapy, ICR fraction size, RP ratio (dose at the rectal point according to the Point A dose), MP ratio (dose at the maximal rectal point according to the Point A dose), EBRT dose, BEDPoint A, BEDRP, and BEDMP. RESULTS. The 5-year actuarial overall rate of LRC ≥ Grade 2 in all patients was 18.4%. Univariate analysis showed that the RP ratio, MP ratio, EBRT dose, BEDpoint A, BEDRP, and BEDMP were correlated with LRC ≥ Grade 2 (P < 0.05). Multivariate analysis showed that, of all clinical and dosimetric parameters evaluated, only BEDRP was correlated with LRC ≥ Grade 2(P = 0.009). The 5-year actuarial rate of LRC ≥ Grade 2 was 5.4% in patients with a BEDRP < 125 Gy 3 and 36.1% in patients with a BEDRP ≥ 125 Gy 3 (P < 0.001). CONCLUSIONS. BEDRP was a useful dosimetric parameter for predicting the risk of LRC ≥ Grade 2 and should be limited to < 125 Gy3 whenever possible to minimize the risk of LRC ≥ Grade 2 in patients with uterine cervical carcinoma who are treated with a combination of EBRT and HDR-ICR.

Original languageEnglish
Pages (from-to)1304-1311
Number of pages8
JournalCancer
Volume104
Issue number6
DOIs
Publication statusPublished - 2005 Sep 15

Keywords

  • Dosimetric parameter
  • High-dose-rate intracavitary irradiation
  • Late rectal complication
  • Uterine cervical carcinoma

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

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    Kim, T. H., Choi, J., Park, S. Y., Lee, S. H., Lee, K. C., Yang, D. S., Shin, K. H., Cho, K. H., Lim, H. S., & Kim, J. Y. (2005). Dosimetric parameters that predict late rectal complications after curative radiotherapy in patients with uterine cervical carcinoma. Cancer, 104(6), 1304-1311. https://doi.org/10.1002/cncr.21292