Boost irradiation of breast carcinoma: teletherapy vs. brachytherapy

The results of adjuvant radiotherapy including a boost dose after breast-conserving surgery of mamma carcinoma were retrospectively analysed to relate local tumor control, survival, and cosmetic results to the boost technique.

The study included 229 female patients who were treated in the period 1986--1997. Group A consisted of patients where the primary irradiation was hyperfractionated (two fractions per day) and the boost was applied by reduced portals, also at two fractions per day. In group B the 'boost' was applied interstitially intraoperatively and the 'primary' irradiation followed at one fraction per day. The cosmetic results and the late changes to the mamma were the subjects of follow-up examinations and were assessed using the EORTC score.

129 patients formed group A, median follow-up 4.2 years, and 100 patients with median follow-up of 9.4 years formed group B. 59% of group A and 60% of group B were in stage pT1, 38% and 39% were in pT2, and 25% and 39% were in stage N1 or N2 (no significant differences). Tumors were mostly poorly to moderately differentiated. The upper outer quadrant was most afflicted. Local recurrence occurred in two and five cases, lymph-node recurrence in two cases each, while there were ten and 12 cases of distant metastases. There were no deaths in group A and in group B six with obvious distant metastases and eight with other causes of death. The cosmetic results and late side-effects (induration, teleangiectasis, ulcers) were significantly worse in the interstitial group B. Multivariate analysis revealed that only the total applied dose significantly affected the severity of late radiation side-effects. The cosmetic results worsened with time, the tendency for lymph edemas in the irradiated side increased. Induration decreased continuously after pure teletherapy but increased continuously after interstitial therapy. These trends did not change in either group.

Both therapy schemes resulted in successful local tumor control with good cosmetic results and few side effects, but the interstitial boost therapy was clearly less favourable. Longer-term follow-up is required to compare the late side-effects even further.