Resumen de Quantitative assessments of radiation-induced toxicity and correlation with rtog scales and biological equivalent dose in breast cancer
Background: Radiation-induced toxicity (RIT) is usually assessed by inspection and palpation. Due to its subjective and unquantitative nature, objective methods are required. This study aimed to determine whether our quantitative tool is able to assess late RIT and establish an underlying BED-response relationship using both subjective and objective assessments. Furthermore, radiotherapy combined with breast reconstruction can reduce the risk of cancer recurrence and increase the survival rate. However, this approach seems to worsen aesthetic outcomes and increase complication rates. The impact of breast reconstruction timing and techniques on clinical outcomes, however, remains unclear. Methods: Patients were grouped according to the radiation biological equivalent dose (BED) used. A total of 7 groups of patients were recruited into our study. RIT was subjectively evaluated by physicians using the Radiation Therapy Oncology Group (RTOG) acute and late toxicity scores. An objective multiprobe device was also used to quantitatively assess late RIT in terms of erythema, pigmentation, elasticity and skin hydration. For further study, patients undergoing RT and breast reconstruction were divided into 4 groups according to the timing of reconstruction (before radiotherapy, after radiotherapy) and surgical technique (heterologous reconstruction, autologous reconstruction). The median time between radiotherapy and reconstruction, number of revision surgeries, incidence of complications, toxicity, aesthetics and associated clinical risk factors were used to assess the clinical outcomes. The objective multiprobe device was also used to assess RIT. Results: In 194 patients, in terms of the objective measurements, treated breasts showed higher erythema and melanin and lower elasticity and hydration than untreated breasts (p<0.001, p<0.001, p<0.001, p=0.019, respectively). As the BED increased, Δerythema and Δmelanin gradually increased as well (p=0.006 and p=0.002, respectively). Regarding the clinical assessment, the increase in BED resulted in a higher acute RTOG (p<0.001) and late RTOG toxicity grade (p<0.001). As the RTOG toxicity grade increased, the erythema values increased, and the elasticity index decreased (p=0.003, p<0.001, respectively). For further study, 95 patients undergoing reconstruction and radiotherapy were included. No significant differences in the median time between radiotherapy and reconstruction, incidence of complications, toxicity, or aesthetics were noted between different timings or techniques of reconstruction. Patients undergoing autologous reconstruction needed more revision surgeries to complete reconstruction. However, the total number of surgical procedures was similar between the groups. In a comparison between the treated and untreated breasts by the objective system, radiotherapy produced an increase in erythema and pigmentation and a decrease in elasticity in the treated breast (p<0.05 for all parameters). On multivariate analysis, smoking was a significant predictor associated with complications. Conclusions: The Multi Skin Test Center is a useful tool to assess RIT. Physician-assessed toxicity score and objective measurements revealed that the higher BED was associated with severity of toxicity. Focusing on carefully selecting radiation schedule will be fruitful for patient care. Combined breast reconstruction and radiotherapy seems to be successful regardless of the order of treatment or the type of reconstruction.
