The time dose fractionation (TDF) relationship in the radiotherapy of carcinoma of the cervix.

A retrospective analysis of 291 patients with cancer of the uterine cervix treated with a combination of external and intracavitary radiotherapy was carried out. Patients were either treated with 45 Gy in 20 fractions by five fractions per week or with 42 Gy in 14 fractions by three fractions per week schedule by external radiotherapy. For brachytherapy the total dose was 24 to 32 Gy at a dose rate of 1.4 to 2.2 Gy per hour. Treatment results in terms of response, survival, recurrence and complication were correlated with total TDF values for point A (TDFTA) and for rectum TDFTR. Correlations of TDFTA with overall complication rate (p value less than 0.05) and rectal complications rate (p value less than 0.01) were excellent. TDFTA values did not correlate with response, recurrence and survival rates (p value greater than 0.1). Lack of correlation was observed between TDFTR and overall complication rate (p value greater than 0.1) as well as rectal complication rate (p value greater than 0.1). In order to limit grade II and III rectal and bladder complications to acceptable level, in combined external and intracavitary treatments, TDFTA value of less than 150 is suggested.