Acute radiation reaction and local control in breast cancer patients treated with postmastectomy radiotherapy.

BACKGROUND: We have investigated the variation of acute radiation reactions in medium-risk patients with postmastectomy radiotherapy with regard to a possible correlation between radiation reaction of normal tissues and local tumor control.
MATERIAL AND METHODS: From 1985 through 1991, a total number of 194 patients received postmastectomy radiotherapy for breast cancer pT1-2pN0-2M0 at the University of Halle-Wittenberg. The lymphatics were irradiated by an anterior 9-MV photon field and the chest wall by an individually shaped anterior field with 9-MV electrons. Both fields received single doses of 2 Gy 5 times weekly up to a total dose of 44 Gy to the chest wall and 50 Gy to the lymphatics. All patients were routinely evaluated once weekly during radiotherapy for acute side effects by one examiner. Skin erythema was classified as mild, moderate or severe, esophagitis as being present in form of dysphagia or not and pneumonitis, if present, as asymptomatic (visible only on repeated chest X-rays) or clinically symptomatic. A differential blood count was also carried out once weekly. For this analysis, the records of all patients were retrospectively reviewed. The median follow-up at the time of analysis was 4.2 years.
RESULTS: Of the patients, 98 (51%) had a mild, 53 (27%) moderate and 43 (22%) a severe erythema. Furthermore, 38 patients (20%) had signs of esophagitis, 13 (7%) had asymptomatic and 26 (13%) symptomatic pneumonitis. Patients with severe erythema or erythema plus esophagitis and pneumonitis had a more pronounced decrease in lymphocyte count during treatment than patients with mild erythema: the lymphocyte nadir was 0.14 vs 0.73 Gpt/l in patients with severe vs mild erythema, and 0.36 vs 0.69 Gpt/l in patients with erythema plus esophagitis plus pneumonitis vs patients with erythema only, p < 0.05. Of the patients, 44 (22%) developed chronic side effects, mostly arm edema. There was no correlation between acute and late effects. An overall number of seven local recurrences (3.6%) occurred. The risk of developing a local recurrence within 5 years after treatment was 0% in patients with severe erythema or erythema plus esophagitis/pneumonitis vs 7% in patients with mild erythema only; this difference was marginally significant, p = 0.055.
CONCLUSIONS: This analysis showed a trend towards better local control in patients with severe acute radiation reaction of normal tissue. The data support a recent publication by Dahl and coworkers showing a linkage between acute radiation reaction of normal tissue and tumor response in patients with preoperative radiotherapy for rectal cancer. The correlation between acute normal tissue reaction and local control might be explained by interindividual variations in the intrinsic, genetically determined radiosensitivity. However, local factors might also be involved, e.g. induction of a cytokin cascade in cases of acute reactions in normal tissues.