Objective To observe the longitudinal changes of symptoms in the irradiation area of patients with postoperative radiotherapy for breast cancer, and investigate the correlative symptom indexes for predicting acute radiation dermatitis during radiotherapy. Methods: This study was designed as a prospective longitudinal study. A total of 103 patients with breast cancer who received three-dimensional conformal radiotherapy in The Fourth Hospital of Hebei Medical University from May 2022 to December 2022 were enrolled using convenience and purposive sampling methods. The patients received a total of 50 Gy/25 radiotherapy sessions. We conducted weekly observations of five symptoms-itching, pain, swelling, burning, and tightness-in the irradiated area, for a total of six weeks. The incidence of symptoms associated with radiation dermatitis across different severity levels was compared. We calculated the optimal number of symptoms for the occurrence of grade 2 or higher radiation dermatitis, evaluated the predictive effect using the subject's work characteristic curve (ROC), and compared the risk of radiation dermatitis with the number of symptoms by applying a binary Logistic regression.

Results A total of 103 patients were included in the study. The total severity scores of symptoms were 0 (0, 0), 0 (0, 0), 0 (0, 1), 1 (0, 2), 2 (1, 3), 3 (2, 4), respectively, showing a gradually increasing trend. From the 20 Gy/10-fraction radiotherapy point onward to the completion of radiotherapy, symptom scores exhibited statistically significant deviations from baseline values (P<0.001). From the beginning of 30 Gy/15 sessions to the end of radiotherapy, symptom scores were higher in patients with grade 2 and above dermatitis compared to those with dermatitis of less than grade 2 (Z=2.12, 2.81, 4.08, P=0.034, 0.005, 0.001); at the end of 50Gy/25 sessions, the incidence rates of pruritus, pain, swelling, tightness, and burning were 68.9% (71 cases), 68.9% (71 cases), 46.6% (48 cases), 36.9% (38 cases), and 15.5% (16 cases), respectively. At the 30 Gy/15 and 40 Gy/20 radiotherapy sessions, the optimal number of predicted symptoms were two and three, respectively. The corresponding areas under the ROC curve were 0.632 and 0.666. Sensitivity values were 48.6% and 43.2%, while specificity values reached 77.3% and 81.8%, respectively (95% CI: 0.517–0.746, 0.558–0.775, P=0.027, 0.005). The subjects were assigned into low-risk and high-risk groups using the optimal cut-off values, and binary Logistic regression showed that the risks of grade 2 and higher radiation dermatitis in the high-risk group were 3.39 and 3.58 times higher than that in the low-risk group (OR=3.388, 95%CI: 1.400–8.197, P=0.007; OR=3.584, 95%CI: 1.430–8.985, P=0.006).

Conclusions The symptoms of radiation dermatitis have appeared early and worsened with the severity of dermatitis. We should closely observe these symptoms throughout treatment. The risk of grade 2 and above radiation dermatitis increased when the number of symptoms was ≥2 at 30 Gy/15 times and ≥3 at 40 Gy/20 times.