Lessons of studies of breast-conserving therapy with and without whole-breast irradiation for patient selection for partial-breast irradiation

Evaluation of single nucleotide polymorphisms (SNPs) in the p53 binding protein 1 (TP53BP1) gene in breast cancer patients treated with breast-conserving surgery and whole-breast irradiation (BCS + RT)

PURPOSE

TP53BP1 is a key component of radiation-induced deoxyribonucleic acid damage repair. The purpose of this study was to evaluate the significance of a known common single nucleotide polymorphism in this gene (rs560191) in patients treated with breast-conserving surgery and whole-breast irradiation (BCS + RT).

METHODS AND MATERIALS

The population consisted of 176 premenopausal women treated with BCS + RT (median follow-up, 12 years). Genomic deoxyribonucleic acid was processed by use of TaqMan assays. Each allele for rs560191 was either C or G, so each patient was therefore classified as CC, CG, or GG. Patients were grouped as GG if they were homozygous for the variant G allele or CC-CG if they carried at least one copy of the common C allele (CC or CG).

RESULTS

Of the 176 women, 124 (71%) were CC-CG and 52 (29%) were GG. The mean age was 44 years for GG vs. 38 years for CC-CG (p < 0.001). GG was more common in African-American women than white women (69% vs. 13%, p < 0.001) and more commonly estrogen receptor negative (70% vs. 49%, p = 0.02). There were no significant correlations of rs560191 with other critical variables. Despite the fact that GG patients were older, the 10-year rate of local relapses was higher (22% for GG vs. 12% for CC-CG, p = 0.04).

CONCLUSIONS

This novel avenue of investigation of polymorphisms in radiation repair/response genes in patients treated with BCS + RT suggests a correlation to local relapse. Additional evaluation is needed to assess the biological and functional significance of these single nucleotide polymorphisms, and larger confirmatory validation studies will be required to determine the clinical implications.

Radiation Therapy in the Treatment of Breast Cancer

OBJECTIVES

To explore the advancements in radiation therapy for patients with breast cancer. To review the side effects associated with radiation therapy to the breast.

DATA SOURCES

Medical and nursing journals and texts.

CONCLUSION

Advances in technology and a shift in the paradigm used to treat breast cancer are leading to newer and accelerated methods of treatment. APBI has gained increased attention and is the subject of numerous clinical trials.

IMPLICATIONS FOR NURSING PRACTICE

Nurses must be aware of the technical aspects associated with new technology and the rationale and implications associated with its use. The focus for nurses working in radiation therapy continues to be patient education and side effect management. Nurses must understand the ramifications such treatment entails so as to provide optimal care.

Accelerated partial-breast irradiation using proton beams: initial clinical experience

PURPOSE

We present our initial clinical experience with proton, three-dimensional, conformal, external beam, partial-breast irradiation (3D-CPBI).

METHODS AND MATERIALS

Twenty patients with Stage I breast cancer were treated with proton 3D-CPBI in a Phase I/II clinical trial. Patients were followed at 3 to 4 weeks, 6 to 8 weeks, 6 months, and every 6 months thereafter for recurrent disease, cosmetic outcome, toxicity, and patient satisfaction.

RESULTS

With a median follow-up of 12 months (range, 8-22 months), no recurrent disease has been detected. Global breast cosmesis was judged by physicians to be good or excellent in 89% and 100% of cases at 6 months and 12 months, respectively. Patients rated global breast cosmesis as good or excellent in 100% of cases at both 6 and 12 months. Proton 3D-CPBI produced significant acute skin toxicity with moderate to severe skin color changes in 79% of patients at 3 to 4 weeks and moderate to severe moist desquamation in 22% of patients at 6 to 8 weeks. Telangiectasia was noted in 3 patients. Three patients reported rib tenderness in the treated area, and one rib fracture was documented. At last follow-up, 95% of patients reported total satisfaction with proton 3D-CPBI.

CONCLUSIONS

Based on our study results, proton 3D-CPBI offers good-to-excellent cosmetic outcomes in 89% to 100% of patients at 6-month and 12-month follow-up and nearly universal patient satisfaction. However, proton 3D-CPBI, as used in this study, does result in significant acute skin toxicity and may potentially be associated with late skin (telangiectasia) and rib toxicity. Because of the dosimetric advantages of proton 3D-CPBI, technique modifications are being explored to improve acute skin tolerance.

Electron intraoperative treatment in patients with early-stage breast cancer: data update

Intraoperative radiotherapy is a technique where a high, single-fraction radiation dose is delivered directly to the tumor bed during a surgical procedure, after the removal of a neoplastic mass, with minimal exposure of surroundings tissues, which are displaced and shielded during the procedure. Intraoperative radiotherapy has been used in the treatment of various malignancies, mostly in combination with external beam radiation therapy. The long-term results suggest a positive impact on local controls that appear to be associated with increased survival. Modern intraoperative radiotherapy can be performed either with electron beams or photons, and has been used recently in early-stage cancer as a boost or as an exclusive treatment, especially for breast tumors, with extremely promising results. The results of different clinical studies have demonstrated the feasibility of the technique and it is expected that its application will become more widespread in the immediate future. Intraoperative electron radiotherapy in the treatment of initial-stage breast cancer may be an excellent alternative to external beam radiation therapy in an appropriate selected group of patients. However, intensive long-term follow-up is required for a better evaluation of local control and possible side effects.

Initial Outcomes for Patients Treated on the American Society of Breast Surgeons MammoSite Clinical Trial for Ductal Carcinoma-In-Situ of the Breast

BACKGROUND

The MammoSite device was designed as a breast brachytherapy applicator and is currently used to deliver accelerated partial breast irradiation (APBI). We hypothesized that APBI delivered with the MammoSite device would be well tolerated and be associated with a good cosmetic outcome in patients with ductal carcinoma-in-situ (DCIS).

METHODS

From 2002 to 2004, 191 patients with DCIS were enrolled in a registry trial to assess the MammoSite applicator. Fifteen patients were excluded from analysis because of device- or patient-related factors; 7 patients were excluded after receiving a radiotherapy boost, thus leaving 169 patients available for study. Follow-up information was available for 158 patients. The average length of follow-up was 7.35 months. Forty-three patients had at least 1 year of follow-up.

RESULTS

Skin spacing for the MammoSite applicator was as follows: < 5 mm, 3 patients (1.78%); 5 to 7 mm, 18 patients (10.65%); and > or = 7 mm, 148 patients (87.57%). Patients with a device-to-skin distance of > or = 7 mm had the best cosmetic result. Patients with a device-to-skin distance of > or = 7 mm also had a lower incidence of radiation dermatitis. Data on 43 patients who were followed up for at least 1 year confirmed these findings. Additional adverse events were primarily related to skin changes, with breast infections occurring in five patients (3.16%). No patient in the study has experienced a recurrence.

CONCLUSIONS

APBI delivered via MammoSite is well tolerated in patients with DCIS, and the lowest toxicity was obtained in patients with the greatest device-to-skin distance. Long-term follow-up data regarding patient satisfaction, cosmesis, and efficacy are needed and will be determined from a recently opened large randomized study.