Late effects of dose fractionation on the mechanical properties of breast skin following post-lumpectomy radiotherapy

Purpose: Late radiation-induced skin effects were studied in a multicenter project using our new sensitive noninvasive viscoelasticity skin analyzer ( VESA), Methods and Materials: Skin viscoelasticity and anisotropy were examined qu antitatively in symmetric areas of both breasts in healthy women and in 110 breast cancer patients who underwent lumpectomy and radiotherapy. These pa rameters were evaluated by the VESA measurement of the speed of elastic wav e propagation in the skin; higher VESA readings correspond to higher skin s tiffness. Effect of radiation was estimated by comparison of the data recor ded in the irradiated versus nonirradiated breast of the same patient. Results: Skin viscoelasticity and anisotropy were similar in contralateral areas of the breasts in healthy controls as well as in the nonirradiated br easts of the patients. With age, skin viscoelasticity decreased and anisotr opy increased similarly in both breasts. Radiotherapy, by a total radiation dose in the range of 45-50 Gy given with 1.8 Gy/fraction (fx) resulted in a similar minor, but still statistically significant, increase of skin stif fness relative to control. The effect was more pronounced when a dose of 50 Gy was given in a higher dose/fraction of 2.5 Gy, Conclusion: We found that the increase in dose of radiation per fraction ha d much more impact on the development of late skin effects than elevation i n the total dose given. (C) 1999 Elsevier Science Inc.