Relationship between early and late normal-tissue injury after postmastectomy radiotherapy.
Factors of importance in the development of telangiectasia were investigated in a series of 229 patients who, between 1978 and 1982, received postmastectomy radiotherapy with two different fractionation schedules. Patients who developed moist desquamation had a statistically significantly increased risk of developing telangiectasia after a specific course of radiotherapy. As an example the estimated incidence of severe telangiectasia after 44 Gy in 22 fractions increases from 27% to 49% in patients who developed grade greater than or equal to 2 moist desquamation as an early radiation reaction. A reanalysis of the Aarhus data with telangiectasia as the endpoint gave an alpha/beta ratio at 2.8 Gy (95% c.l. (-0.1, 8.1) Gy) and a relative biological effectiveness (RBE) of high energy electrons relative to 8 MV photons at 0.89 (95% c.l. (0.85, 0.93)). Patients age or the occurrence of severe erythema did not predispose to telangiectasia. A similar predisposition after moist desquamation was not seen for subcutaneous fibrosis. The RBE of high energy electrons relative to 8 MV photons for this endpoint was estimated at 0.88 (95% c.l. (0.86, 0.91].
Bentzen
S M
SM
Department of Medical Physics, Danish Cancer Society, Aarhus.
Overgaard
M
M
D001943:Breast Neoplasms / Q000532:radiotherapy* / Q000601:surgery; D003131:Combined Modality Therapy; D005260:Female; D005355:Fibrosis; D006801:Humans; D008408:Mastectomy; D011832:Radiation Injuries / Q000473:pathology*; D011878:Radiotherapy / Q000009:adverse effects; D011879:Radiotherapy Dosage; D012867:Skin / Q000473:pathology*; D013684:Telangiectasis / Q000209:etiology*; D013997:Time Factors