[Evidence-based radiotherapy in the treatment of early-stage invasive breast cancer: traditional clinical features and biomarkers].

Adjuvant radiotherapy after modified radical mastectomy and breast-conserving surgery for early-stage invasive breast cancer substantially reduces the risk of locoregional failure and is evidence-based. Using traditional clinical and pathological factors, patients can be classified into subgroups by the risk of locoregional recurrence. In the high-risk groups the absolute benefit of irradiation is larger. However, the patients are over-treated in every subgroup. Substantial proportion of the patients remains free of locoregional recurrence even in the absence of irradiation, and some patients develop locoregional recurrence despite postoperative irradiation. Molecular markers may provide sufficient information to allow accurate individual risk assessment to identify patients who might benefit from irradiation. Despite of hundreds of reports on tumor markers, results are controversial and the number of validated markers for clinical practice is small. Prognostic and predictive factors commonly used in radiotherapy practice are ER, PgR and HER-2. Adjuvant radiotherapy not only reduces locoregional recurrence rates but also improves cancer-specific survival in patients receiving systemic therapy. The highest mortality reduction is observed in mastectomy patients with good prognostic factors (<4 positive nodes, tumor size <2 cm, Grade 1 malignancy, ER- and PgR-positive, HER-2-negative). After mastectomy the chest wall, and after breast conserving surgery the ipsilateral breast are the sites at greatest risk of recurrence. The risk of axillary recurrence is low in patients undergoing axillary dissection. Axillary and supraclavicular recurrences generally forecast a grim prognosis, and they are indicators of distant dissemination. Improvement in survival resulting from the use of irradiation is more related to the prevention of local recurrences. Post-irradiation local recurrence increases the risk of mortality, but with good prognostic factors the 10-year survival is 80-90%. Patients with </=2 cm ipsilateral breast recurrence might receive a second conservative surgery. The radiation dose to the lung and heart can be significantly reduced by individualized CT-based treatment planning. The rate of Grade 3 atrophic dermatitis and fibrosis is 3-4%. The estimated incidence of ipsilateral breast angiosarcoma is less than 0.2%, but the mortality rate is high.