Rectovaginal fistula risk doses in patients with cervical cancer

Abstract

Purpose

To evaluate the incidence and risk factors, both clinical and physical, of the development of a postradiation recto-vaginal fistula in cervical cancer patients.

Materials and methods

A retrospective analysis of 222 consecutive patients receiving radical treatment for invasive cervical cancer at the Regional Oncology Centre in Bydgoszcz between 1993 and 1995 has been performed, on 140 patients treated with radiotherapy alone and 82 patients who received radiotherapy combined with surgical treatment. The doses and dose rates of brachytherapy were specified at point A, the mean dose being 49 and 46 Gy for radiotherapy alone and combined treatment, respectively. External beam irradiation was applied in fractions of 1.8–2 Gy, up to a total dose of 44.6 Gy (36–50 Gy). The dose and dose rate in the rectum (point R₁) were determined according to the protocol 38th ICRU, the biological extrapolated dose (BED), using a LQ model, was calculated as a sum of a dose from external beam irradiation and brachytherapy.

Results

A total of 17 (7.6%) recto-vaginal cases of fistulae were found; 13 (9,2%) in patients treated with radiotherapy alone, 4 (4,8%) in patients treated with combined treatment. The median latency time was 11.8 months (range 7 to 24). There is a strong association between the risk of developing a fistula and the biological extrapolated dose (BED) at point R₁. Addition of surgical treatment results in a higher risk of complications. Age, clinical stage, hemoglobin level, performance status and the overall treatment time, type and size of applicators were not found to have a significant effect on the risk of developing recto-vaginal fistula.

Conclusions

The biological extrapolated dose (BED) at point R₁ is an important predictive factor relevant for postradiotherapeutic rectovaginal fistula incidence risk. Surgery is an important factor modifying the postradiotherapeutic rectovaginal fistula incidence risk. No significant influence on the fistula incidence risk of such parameters as age, FIGO stage, physical activity, haemoglobin level, overall treatment time, type and size of applicators has been demonstrated.