Acute Radiation Toxicity
Acute radiation toxicities are side effects that occur on treatment or in the immediate posttreatment period. Onset may be 2–3 weeks after the commencement of a regimen of radiation therapy. Typically, severity and timing are tied to the total biologic dose and the turnover rate of the tissue in question, respectively. It is less dependent on the dose per fraction of treatment. In the case of whole breast radiation therapy, radiation dermatitis usually involves mild puritis and erythema of the skin. Some cases involve patchy moist desquamation in the folds of the axilla and inframammary regions. In the modern era, these side effects are nearly always mild (∼95% of cases are grade 1–2). The degree of dermatitis may be slightly more severe in large-breasted patients and in patients with underlying DNA repair deficits such as ATM heterozygosity. Radiation dermatitis usually resolves rapidly (2–3 weeks post treatment) and results in temporary...