Novel approaches to postoperative radiation therapy as part of breast-conserving therapy for early-stage breast cancer

Novel applications of proton therapy in breast carcinoma

This review will focus on the indications, clinical experience, and technical considerations of proton beam radiation therapy in the treatment of patients with breast cancer. For patients with early stage disease, proton therapy delivers less dose to non-target breast tissue for patients receiving partial breast irradiation (PBI) therapy, which may result in improved cosmesis but requires further investigation. For patients with locally advanced breast cancer requiring treatment to the regional lymph nodes, proton therapy allows for an improved dosimetric profile compared with conventional photon and electron techniques. Early clinical results demonstrate acceptable toxicity. The possible reduction in cardiopulmonary events as a result of reduced dose to organs at risk will be tested in a randomized control trial of protons vs. photons.

Progress and controversies: radiation therapy for invasive breast cancer

Radiation therapy is a critical component of the multidisciplinary management of invasive breast cancer. In appropriately selected patients, radiation not only improves local control, sparing patients the morbidity and distress of local recurrence, but it also improves survival by preventing seeding and reseeding of distant metastases from persistent reservoirs of locoregional disease. In recent years, considerable progress has been made toward improving our ability to select patients most likely to benefit from radiotherapy and to administer treatment in ways that maximize clinical benefit while minimizing toxicity and burden. This article reviews the role of radiation therapy in invasive breast cancer management, both after breast-conserving surgery and after mastectomy. It focuses particularly on emerging evidence that helps to define the clinical situations in which radiotherapy is indicated, the appropriate targets of treatment, and optimal approaches for minimizing both the toxicity and the burden of treatment, all in the context of the evolving surgical and systemic management of this common disease. It includes a discussion of new approaches in breast cancer radiotherapy, including hypofractionation and intensity modulation, as well as a discussion of promising avenues for future research.

Three-year outcomes of a once daily fractionation scheme for accelerated partial breast irradiation (APBI) using 3-D conformal radiotherapy (3D-CRT)

The aim of this study was to report 3-year outcomes of toxicity, cosmesis, and local control using a once daily fractionation scheme (49.95 Gy in 3.33 Gy once daily fractions) for accelerated partial breast irradiation (APBI) using three-dimensional conformal radiotherapy (3D-CRT). Between July 2008 and August 2010, women aged ≥40 years with ductal carcinoma in situ or node-negative invasive breast cancer ≤3 cm in diameter, treated with breast-conserving surgery achieving negative margins, were accrued to a prospective study. Women were treated with APBI using 3–5 photon beams, delivering 49.95 Gy over 15 once daily fractions over 3 weeks. Patients were assessed for toxicities, cosmesis, and local control rates before APBI and at specified time points. Thirty-four patients (mean age 60 years) with Tis 0 (n = 9) and T1N0 (n = 25) breast cancer were treated and followed up for an average of 39 months. Only 3% (1/34) patients experienced a grade 3 subcutaneous fibrosis and breast edema and 97% of the patients had good/excellent cosmetic outcome at 3 years. The 3-year rate of ipsilateral breast tumor recurrence (IBTR) was 0% while the rate of contralateral breast events was 6%. The 3-year disease-free survival (DFS), overall survival (OS), and breast cancer-specific survival (BCSS) was 94%, 100%, and 100%, respectively. Our novel accelerated partial breast fractionation scheme of 15 once daily fractions of 3.33 Gy (49.95 Gy total) is a remarkably well-tolerated regimen of 3D-CRT-based APBI. A larger cohort of patients is needed to further ascertain the toxicity of this accelerated partial breast regimen.

Unacceptable cosmesis in a protocol investigating intensity-modulated radiotherapy with active breathing control for accelerated partial-breast irradiation

PURPOSE

To report interim cosmetic results and toxicity from a prospective study evaluating accelerated partial-breast irradiation (APBI) administered using a highly conformal external beam approach.

METHODS AND MATERIALS

We enrolled breast cancer patients in an institutional review board-approved prospective study of APBI using beamlet intensity-modulated radiotherapy (IMRT) at deep-inspiration breath-hold. Patients received 38.5 Gy in 3.85 Gy fractions twice daily. Dosimetric parameters in patients who maintained acceptable cosmesis were compared with those in patients developing unacceptable cosmesis in follow-up, using t-tests.

RESULTS

Thirty-four patients were enrolled; 2 were excluded from analysis because of fair baseline cosmesis. With a median follow-up of 2.5 years, new unacceptable cosmesis developed in 7 patients, leading to early study closure. We compared patients with new unacceptable cosmesis with those with consistently acceptable cosmesis. Retrospective analysis demonstrated that all but one plan adhered to the dosimetric requirements of the national APBI trial. The mean proportion of a whole-breast reference volume receiving 19.25 Gy (V50) was lower in patients with acceptable cosmesis than in those with unacceptable cosmesis (34.6% vs. 46.1%; p = 0.02). The mean percentage of this reference volume receiving 38.5 Gy (V100) was also lower in patients with acceptable cosmesis (15.5% vs. 23.0%; p = 0.02).

CONCLUSIONS

The hypofractionated schedule and parameters commonly used for external beam APBI and prescribed by the ongoing national trial may be suboptimal, at least when highly conformal techniques such as IMRT with management of breathing motion are used. The V50 and V100 of the breast reference volume seem correlated with cosmetic outcome, and stricter limits may be appropriate in this setting.

Phase I-II Trial of Prone Accelerated Intensity Modulated Radiation Therapy to the Breast to Optimally Spare Normal Tissue

Purpose

To report the clinical feasibility of a trial of accelerated whole-breast intensity modulated radiotherapy, with the patient in prone position, optimally to spare the heart and lung.

Patients and Methods

Patients with stages I or II breast cancer, excised by breast conserving surgery with negative margins, were eligible for this institutional review board–approved prospective trial. Computed tomography simulation was performed with the patient prone on a dedicated breast board, in the exact position used for treatment. A dose of 40.5 Gy, delivered at 2.7 Gy in 15 fractions, was prescribed to the index breast with an additional concomitant boost of 0.5 Gy delivered to the tumor bed, for a total dose of 48 Gy to the lumpectomy site. Physics constraints consisted of limiting ≤ 5% of the heart volume to receive ≥ 18 Gy and ≤ 10% of the ipsilateral lung volume to receive ≥ 20 Gy.

Results

Between September 2003 and August 2005, 91 patients were enrolled on the study. Median length of follow-up was 12 months (range, 1 to 28 months). In all patients the technique was feasible and heart and lung sparing was achieved as prescribed by the protocol. Acute toxicities consisting mostly of reversible grades 1-2 skin dermatitis (67%) and fatigue (18%) occurred in 75 patients. One patient sustained a regional recurrence rapidly followed by distant metastases.

Conclusion

Accelerated whole breast intensity modulated radiotherapy in the prone position is feasible and it permits a drastic reduction in the volume of lung and heart tissue exposed to significant radiation.

A treatment planning study comparing whole breast radiation therapy against conformal, IMRT and tomotherapy for accelerated partial breast irradiation

PURPOSE AND BACKGROUND

Conventional early breast cancer treatment consists of a lumpectomy followed by whole breast radiation therapy. Accelerated partial breast irradiation (APBI) is an investigational approach to post-lumpectomy radiation for early breast cancer. The purpose of this study is to compare four external beam APBI techniques, including tomotherapy, with conventional whole breast irradiation for their radiation conformity index, dose homogeneity index, and dose to organs at risk.

METHODS AND MATERIALS

Small-field tangents, three-dimensional conformal radiation therapy, intensity-modulated radiation therapy and helical tomotherapy were compared for each of 15 patients (7 right, 8 left). One radiation conformity and two dose homogeneity indices were used to evaluate the dose to the target. The mean dose to organs at risk was also evaluated.

RESULTS

All proposed APBI techniques improved the conformity index significantly over whole breast tangents while maintaining dose homogeneity and without a significant increase in dose to organs at risk.

CONCLUSION

The four-field IMRT plan produced the best dosimetric results; however this technique would require appropriate respiratory motion management. An alternative would be to use a four-field conformal technique that is less sensitive to the effects of respiratory motion.

Partial breast irradiation: Ready for routine?

Breast-conserving treatment is considered the standard therapy for most early-stage breast cancer and has given excellent results. That notwithstanding in the last years, several institutions are trying to revisit the adjuvant radiation treatment setting, especially with respect to possible changes in overall treatment time and target volume within the philosophy of modern partial breast irradiation. Up to date, no conclusive data are available on the possible role of partial breast irradiation in early-stage breast cancer but in this paper, we review the rationale and the researches currently being undertaken within the framework of this approach, trying to answer whether, in spite of the absence of the randomized evidence of the equivalence between whole and partial breast irradiation, could be already possible to suggest this treatment modality in the daily clinical practice, at least in some selected cases.

Meeting Highlights: International Expert Consensus on the Primary Therapy of Early Breast Cancer 2005

The ninth St Gallen (Switzerland) expert consensus meeting in January 2005 made a fundamental change in the algorithm for selection of adjuvant systemic therapy for early breast cancer. Rather than the earlier approach commencing with risk assessment, the Panel affirmed that the first consideration was endocrine responsiveness. Three categories were acknowledged: endocrine responsive, endocrine non-responsive and tumors of uncertain endocrine responsiveness. The three categories were further divided according to menopausal status. Only then did the Panel divide patients into low-, intermediate- and high-risk categories. It agreed that axillary lymph node involvement did not automatically define high risk. Intermediate risk included both node-negative disease (if some features of the primary tumor indicated elevated risk) and patients with one to three involved lymph nodes without additional high-risk features such as HER 2/neu gene overexpression. The Panel recommended that patients be offered chemotherapy for endocrine non-responsive disease; endocrine therapy as the primary therapy for endocrine responsive disease, adding chemotherapy for some intermediate- and all high-risk groups in this category; and both chemotherapy and endocrine therapy for all patients in the uncertain endocrine response category except those in the low-risk group.

Early stage breast cancer conserving treatment: High dose rate brachytherapy boost to the tumour bed

INTRODUCTION

The dose administered to the tumour bed is a risk-factor for local recurrence in localised breast cancer following breast-conserving surgery.

MATERIALS AND METHODS

All patients (n=94) received 50 Gy external beam radiotherapy and one application of 700 cGy at 85% isodose with high dose rate brachytherapy.

RESULTS

Of the cases, 84% were infiltrating ductal carcinoma; 31.2% were G3; 28% were intraductal component > 25%; 54% had margin < 1 cm or unknown. With a mean follow-up of 65 months (range: 36-107 months), the overall actuarial survival at 5 and 8 years was 93.2% and 84.2%, respectively; disease-free survival was 88.3% and 84.6%, respectively; local control was 92.2% and 88.75%, respectively. Local recurrence rate was 5.3%, and distant dissemination rate was 8.5%. Among the risk-factors analysed, only the presence of 4 or more lymph node involvement implied a higher risk for local recurrence (p =0.0001). For distant dissemination, the risk-factors were: 4 or more lymph nodes involved (p = 0.0001),G3 (p =0.029), tumour >3 cm (p = 0.001), irradiation volume with external beam radiotherapy (p =0.0001), and presence of local recurrence (p = 0.001).

CONCLUSION

High dose rate brachytherapy is an effective method for reducing local recurrence, and increasing local control.

TLD skin dose measurements and acute and late effects after lumpectomy and high-dose-rate brachytherapy only for early breast cancer

PURPOSE

This report examines the relationships between measured skin doses and the acute and late skin and soft tissue changes in a pilot study of lumpectomy and high-dose-rate brachytherapy only for breast cancer.

METHODS AND MATERIALS

Thirty-seven of 39 women enrolled in this pilot study of high-dose-rate brachytherapy (37.2 Gy in 10 fractions b.i.d.) each had thermoluminescent dosimetry (TLD) at 5 points on the skin of the breast overlying the implant volume. Skin changes at TLD dose points and fibrosis at the lumpectomy site were documented every 6 to 12 months posttreatment using a standardized physician-rated cosmesis questionnaire. The relationships between TLD dose and acute skin reaction, pigmentation, or telangiectasia at 5 years were analyzed using the GEE algorithm and the GENMOD procedure in the SAS statistical package. Fisher's exact test was used to determine whether there were any significant associations between acute skin reaction and late pigmentation or telangiectasia or between the volumes encompassed by various isodoses and fibrosis or fat necrosis.

RESULTS

The median TLD dose per fraction (185 dose points) multiplied by 10 was 9.2 Gy. In all 37 patients, acute skin reaction Grade 1 or higher was observed at 5.9% (6 of 102) of dose points receiving 10 Gy or less vs. 44.6% (37 of 83) of dose points receiving more than 10 Gy (p < 0.0001). In 25 patients at 60 months, 1.5% telangiectasia was seen at dose points receiving 10 Gy or less (1 of 69) vs. 18% (10 of 56) telangiectasia at dose points receiving more than 10 Gy (p = 0.004). Grade 1 or more pigmentation developed at 1.5% (1 of 69) of dose points receiving less than 10 Gy vs. 25% (14 of 56) of dose points receiving more than 10 Gy (p < 0.001). A Grade 1 or more acute skin reaction was also significantly associated with development of Grade 1 or more pigmentation or telangiectasia at 60 months. This association was most significant for acute reaction and telangiectasia directly over the lumpectomy site (p < 0.001). Grade 1 or more fibrosis, in 25 patients with a 60-month follow-up, occurred in 47.4% (9 of 19) of patients with a volume of 45 cm3 or less covered by the 100% isodose vs. 83.3% (5 of 6) of patients with a larger volume (p = 0.180). Asymptomatic and biopsy-proven fat necrosis occurred in 5 patients. No significant differences in fat necrosis rates according to volume were detected.

CONCLUSIONS

For high-dose-rate brachytherapy to the lumpectomy site, TLD skin dose was significantly related to acute skin reaction and to pigmentation and telangiectasia at 60 months. An acute skin reaction was also significantly associated with the development of telangiectasia at 60 months. TLD skin dose measurement may allow modification of the brachytherapy implant geometry (dwell times and position) to minimize late skin toxicity.

External-beam partial-breast irradiation

Although most studies treating patients with partial-breast irradiation have used brachytherapy, giving such treatment with external-beam techniques has many potential advantages. However, there is only limited published experience using this approach. These include a randomized trial of partial-breast and whole-breast irradiation performed at the Christie Hospital in Manchester, England, and pilot studies (using much more rigorous selection criteria and sophisticated treatment planning) from groups at the University of Southern California, New York University (using prone positioning of patients), and the William Beaumont Hospital (using the supine position). A multi-institutional pilot trial based on the latter technique has been completed, which was designed to test the feasibility of using this approach in the cooperative oncology group setting. The unprecedented rapidity with which the study completed its target accrual indicates the degree of interest in this approach. This review focuses on the rationale and the reported studies of external-beam partial-breast radiation and identifies some specific issues and remaining problems associated with this approach.

Recent advances in the use of radiotherapy to treat early breast cancer

PURPOSE OF REVIEW

The past decade has seen significant advances in the delivery of radiotherapy for breast cancer. This article presents an overview of the most recent advances in radiotherapy for early breast cancer with emphasis on English-language articles published since 1 July 2003.

RECENT FINDINGS

Breast radiotherapy is usually well tolerated. However, the uptake of radiotherapy in the management of breast cancer is less than ideal. Recent research efforts in radiation oncology have concentrated on addressing the uptake of appropriate radiotherapy by quantifying toxicity, further reducing toxicity, and improving the convenience of radiotherapy. Novel radiation techniques such as partial breast irradiation and shortened radiotherapy treatment courses are under development to make radiotherapy more acceptable to patients and referring clinicians. Issues such as the optimal timing of radiotherapy after surgery and integrating the radiation with newer adjuvant systemic therapies remain important research challenges.

SUMMARY

Radiotherapy remains an important component of breast cancer therapy. Improving the acceptance of treatment and minimizing toxicity and inconvenience of treatment should lead to even greater appropriate use.

Prone accelerated partial breast irradiation after breast-conserving surgery: preliminary clinical results and dose-volume histogram analysis

PURPOSE

To report the clinical and dose-volume histogram results of the first 47 patients accrued to a protocol of accelerated partial breast irradiation. Patients were treated in the prone position with three-dimensional conformal radiotherapy after breast-conserving surgery.

METHODS AND MATERIALS

Postmenopausal women with Stage T1N0 breast cancer were eligible only after they had first refused to undergo 6 weeks of standard radiotherapy. Planning CT in the prone position was performed on a dedicated table. The postoperative cavity was defined as the clinical target volume, with a 1.5-cm margin added to determine the planning target volume. A total dose of 30 Gy at 6 Gy/fraction was delivered in five fractions within 10 days.

RESULTS

The median age of the patients was 67.5 years (range, 51-88 years). The median tumor diameter was 9 mm (range, 1.3-19 mm). In all patients, the prescribed dose encompassed the planning target volume. The mean volume of the ipsilateral breast receiving 100% of the prescription dose was 26% (range, 10-45%), and the mean volume contained within the 50% isodose surface was 47% (range, 23-75%). The lung and heart were spared by treating in the prone position. Acute toxicity was modest, limited mainly to Grade 1-2 erythema. With a median follow-up of 18 months, only Grade 1 late toxicity occurred, and no patient developed local recurrence.

CONCLUSION

These data suggest that this approach is well tolerated, with only mild acute side effects and sparing of the heart and lung.