Breast Brachytherapy(BT) can be administered in 3 scenarios: as sole Partial Breast Irradiation (PBI), as a boost after external radiotherapy (ERT), and as part of a second conservative treatment (salvage BT). There are several techniques for Breast BT. The most popular are Interstitial Multicatheter, Balloon devices and Intraoperative RT (TARGIT, electrons). With the balloon, higher doses to organs at risk (OAR), like skin and ribs are usually administered compared with multicatheter; although with the multichannel balloons, the dose distribution can be optimized and reduced at OAR. In this presentation, I will refer more specifically to multicatheter interstitial technique.
Clearly, the irradiated breast volume with BT is much smaller than with ERT. Depending on the indication and scheme, the patient must remain only some hours (1 fraction) or 4-5 days (8-10 fractions) with the implant. When APBI was started, fractionation was longer; now few fractions are preferred. For the boost and in very accelerated or ultra accelerated PBI (vAPBI) single or few fractions can be administered: 1-3 fractions for the boost and 1 fraction of 16 Gy for elderly people, or 3 fractions of 7.45 Gy in vAPBI. The longer the implant, the more possibilities of cutaneous marks and infection.
During the days the patient is implanted, supportive care is indicated: antibiotics (especially in intraoperative procedures, after the tumor removal) and pain-killers. If the tubes must last for several days, daily wound care is mandatory.
There are several toxicity scales to evaluate acute and chronic toxicity: EORTC/RTOG, CTCAE’s, Lent/Soma. Acute toxicity (6-52%): tenderness, pain, erythema, edema, infection (mastitis), fatigue. It is important to remark that in intraoperative procedures, surgery complications are added: pain, hematoma, bleeding, seroma, more possibilities of infection. Chronic toxicity that can appear: skin problems (acromia, hyperchromia, tubs marks due to hollow or pressure or even small punctual keloid, telangiectasia), edema, seroma (5-32%), fibrosis, fat necrosis (1-37%) or infection (3-16%). It seems that the open cavity technique has a higher infection rate than the closed cavity technique. These secondary effects change with time: especially fibrosis and cutaneous changes, that increase with time. To minimize skin toxicity, the distance between the catheter and the skin should be at least 7 mm. And the GEC-ESTRO recommended constraints about OAR (skin, lung, ribs, heart) and implant homogeneity (Implant ≤300cc, DNR ≤0.35, V100>90%, V150< 65cc, V200<15cc), should be respected. Only Pentoxifylline and Vitamin E have been used to reduce radiation-induced breast fibrosis, with some positive results in small, randomized trials. Anyway APBI breast BT has a very low risk profile, and the Grade 3 secondary effects are very rare. Quality of life after PBI is equal or even better that for whole-breast RT, regarding pain and skin changes. This was clearly evidenced in the randomized European trial.
To evaluate cosmesis, may scales/methods have been developed, although none is perfect. Some are more objective than others, some use photographs. The most used And the simplest one is the Harvard scale, although there are others much more reproducible as Breast Reaction Assessment (BRA), Objective Breast Cosmesis Score (OBCS), Breast Analyzing Tool (BAT) and others, such as Patient-Related outcome Measures (PROMs). Both patients and physicians/nurses should evaluate the cosmesis separately. Objective assessments should be combined with subjective assessments. Cosmesis reflects the sum of the severity and prevalence of chronic secondary effects. It worsens slowly with the years and stabilizes between the 6th-7th year after BT. The final cosmetic result is affected for both surgery and radiation changes. It is very important to register the cosmetic result after surgery and before BT, because most of the deformation or asymmetry can be surgical. Excellent or good cosmetic results are observed in more than 90% of the patients. Cosmesis and chronic toxicity can be influenced by other factors, such as age, surgery type, tumor volume, irradiated skin volume, radiation dose, addition of chemotherapy or simultaneous hormonal treatment, infection, connective tissue and skin disorders or other individual factors. There is no evidence that single fractions are worse than multiple fractions (Nice experience: Comparison of 16 Gy single fraction vs 10 fr 3.4 Gy: same outcome on local control, toxicity and cosmesis). In salvage BT, the cosmesis will be worse than in primary APBI, due to previous surgery and Whole-breast RT.
The integration between the late toxicity results, cosmesis and the psychological impact offers a good total evaluation on final Breast BT results. Finally, we cannot forget the negative impact of mastectomy, both psychological and in quality of life; that is why Salvage APBI is so important to preserve the breast.