[Radiotherapy for cervical cancer patients with high-dose rate brachytherapy: application of shielded colpostats]

Two hundred sixty-six cervical cancer patients with histologically proven squamous cell carcinoma were treated with radiotherapy alone at Keio University Hospital between September 1984 and March 1991. All patients received 30 Gy of external whole pelvic irradiation and 20 Gy of pelvic irradiation with a central shield. After 30 Gy of whole pelvic irradiation, high dose rate intracavitary brachytherapy (24-27 Gy) was applied with the shielded colpostats (3 mm lead). The 5-year cumulative survival rate in each stage decreased with the advance of stage (stage I: 82%, II: 67%, III: 43% and IV: 19%). When patients with stage III cervical cancer were classified into three groups according to tumor size (S, M, L), patients in group L had the worst 5-year survival rate (S: 63%, M: 54% and L: 25%). At follow-up visits conducted between 1 and 2 months after the completion of radiation, patients with stage III L had significantly higher rates of persistent disease (61%) and recurrence (26%). There was no correlation between the incidence of rectosigmoid sequelae and dose given by brachytherapy, and shielded colpostats could not decrease the incidence of rectosigmoid sequelae, compared with that with unshielded colpostats (25% vs. 31%). This result suggests that a higher irradiation dose is necessary to control local tumor in stage III L patients and additional doses administered by brachytherapy (6 Gy) may not increase the incidence of rectosigmoid sequelae.