The effect of intensity-modulated radiotherapy and high dose rate brachytherapy on acute and late radiotherapy-related adverse events following chemoradiotherapy of anal cancer.

Background And Purpose: To investigate acute and late radiotherapy-related adverse events following intensity-modulated radiotherapy (IMRT) and high dose rate (HDR) brachytherapy of anal cancer.

Materials And Methods: Fifty-nine consecutive patients treated by chemoradiotherapy for anal squamous cell cancer were evaluated for acute and late radiotherapy-related adverse events. Twenty patients were treated by IMRT and 39 by conventional 3D-radiotherapy. In 29 patients, the boost dose to the primary tumour was given by HDR brachytherapy: 30 patients were treated only by external radiotherapy.

Results: A significant reduction in skin and mucosal eruptions in the female genital area (P=0.04) and in radiotherapy-associated > grade 2 diarrhoea (P=0.004) was observed in patients treated by IMRT. The difference in unplanned gaps during the radiotherapy was highly significant (P=0.004). A correlation between the equivalent dose in 2Gy fractions (EQD2) at the wall of anal canal opposite to the tumour and radiation proctitis was observed. In patients that received the final boost dose to the primary tumour by HDR brachytherapy, a trend towards lower incidence of radiation proctitis was observed (P=0.065).

Conclusions: IMRT significantly reduces acute radiotherapy-associated adverse events in patients treated by chemoradiotherapy for anal cancer. A combination of external radiotherapy and HDR brachytherapy may reduce the risk of late radiation proctitis.