Predictive value of linear-quadratic model in the treatment of cervical cancer using high-dose-rate brachytherapy

Int J Radiat Oncol Biol Phys. 2002 Dec 1;54(5):1377-87. doi: 10.1016/s0360-3016(02)03051-1.

Abstract

Purpose: To determine whether a dose-response relationship exists between the biologic effective dose (BED) at Point A and the bladder and rectum and the clinical outcomes in our experience with external beam radiotherapy (EBRT) and high-dose-rate brachytherapy in the treatment of cervical carcinoma.

Methods and materials: This was a retrospective study. A total of 49 patients with cervical cancer were treated with a combination of EBRT (median 45 Gy, range 41.4-50.4) and high-dose-rate brachytherapy (median 18 Gy; range 18-19, in two fractions). Twenty-three patients received concomitant cisplatin-based chemotherapy. The cumulative BEDs were calculated at Point A (BED10) and at bladder and rectal reference points (BED3) using the linear-quadratic equation. The BED10 values, after incorporating a time factor (BED10tf) in the formula, were also calculated.

Results: In patients treated with RT alone, the local failure rate was 10% (1 of 10) and 19% (3 of 16) in patients receiving a BED10 >89 Gy10 or <89 Gy10 to Point A, respectively (p = 0.2). The corresponding local failure rates were 20% (3 of 15) and 0% (0 of 8) in patients treated with concomitant chemotherapy (p = 0.3). In patients treated with RT alone, the local failure rate was 7.7% (1 of 13) and 23% (3 of 13) in patients with a BED10tf >64 Gy10 or <64 Gy10 (p = 0.1), respectively. The median BED3 values at the rectal and bladder point was 95.5 Gy3 and 103.6 Gy3, respectively. Only 1 case of Grade 2 late rectal toxicity (2%) and no late bladder toxicity occurred.

Conclusion: In patients treated with RT alone, a BED10 >89 Gy and a BED10tf >64 Gy indicated a trend toward a better local control rate. This difference was not observed in patients receiving chemotherapy. A BED3 <100 Gy3 was associated with negligible late toxicity. Although the BED10 in our study was about 10-15 Gy10 less than that in the published data, the 4-year local control rate of 80% and 83% and disease-free survival rate of 75% and 70% with and without chemotherapy, respectively, compare well with the rates in other studies in the literature.

MeSH terms

  • Adenocarcinoma / radiotherapy
  • Adult
  • Brachytherapy / methods*
  • Carcinoma, Squamous Cell / radiotherapy
  • Cisplatin / therapeutic use*
  • Disease-Free Survival
  • Dose Fractionation, Radiation
  • Dose-Response Relationship, Radiation
  • Female
  • Follow-Up Studies
  • Humans
  • Middle Aged
  • Models, Theoretical
  • Radiation-Sensitizing Agents / therapeutic use*
  • Retrospective Studies
  • Time Factors
  • Treatment Outcome
  • Uterine Cervical Neoplasms / radiotherapy*

Substances

  • Radiation-Sensitizing Agents
  • Cisplatin