Morphological factors and cardiac doses in whole breast radiation for left-sided breast cancer

Radiation dose to the heart with hypofractionation in patients with left breast cancer

Introduction

In this study we compared radiation dose received by organs at risk (OARs) after breast conservation surgery(BCS) and mastectomy in patients with left breast cancer.

Materials and methods

Total 30 patients, 15 each of BCS and mastectomy were included in this study. Planning Computerised Tomography (CT) was done for each patient. Chest wall, whole breast, heart, lungs, LAD, proximal and distal LAD, and contra lateral breast was contoured for each patient. Radiotherapy plans were made by standard tangent field. Dose prescribed was 40Gy/16#/3 weeks. Mean heart dose, LAD, proximal and distal LAD, mean and V5 of right lung, and mean, V5, V10 and V20 of left lung, mean dose and V2 of contra lateral breast were calculated for each patient and compared between BCS and mastectomy patients using student’s T test.

Results

Mean doses to the heart, LAD, proximal LAD and distal LAD were 3.364Gy, 16.06Gy, 2.7Gy, 27.5Gy; and 4.219Gy, 14.653Gy, 4.306Gy, 24.6Gy, respectively for mastectomy and BCS patients. Left lung mean dose, V5, V10 and V20 were 5.96Gy, 16%, 14%, 12.4%; and 7.69Gy, 21%, 18% and 16% in mastectomy and BCS patients, respectively. There was no statistical significant difference in the doses to the heart and left lung between mastectomy and BCS. Mean dose to the right lung was significantly less in mastectomy as compared to BCS, 0.29Gy vs. 0.51Gy, respectively (p = 0.007). Mean dose to the opposite breast was significantly lower in patients with mastectomy than BCS (0.54Gy Vs 0.37Gy, p = 0.007). The dose to the distal LAD was significantly higher than proximal LAD both in BCS (24.6Gy Vs 4.3Gy, p = <0.0001) and mastectomy (27.5Gy Vs 2.7Gy, p = <0.0001) patients.

Conclusion

There was no difference in doses received by heart and left lung between BCS and mastectomy patients. Mean doses to the right lung and breast were significantly less in mastectomy patients.

Breast size and dose to cardiac substructures in adjuvant three-dimensional conformal radiotherapy compared to tangential intensity modulated radiotherapy

Background

The aim of the study was to quantify planned doses to the heart and specific cardiac substructures in free-breathing adjuvant three-dimensional radiation therapy (3D-CRT) and tangential intensity modulated radiotherapy (t-IMRT) for left-sided node-negative breast cancer, and to assess the differences in planned doses to organs at risk according to patients’ individual anatomy, including breast volume.

Patients and methods

In the study, the whole heart and cardiac substructures were delineated for 60 patients using cardiac atlas. For each patient, 3D-CRT and t-IMRT plans were generated. The prescribed dose was 42.72 Gy in 16 fractions. Patients were divided into groups with small, medium, and large clinical target volume (CTV). Calculated dose distributions were compared amongst the two techniques and the three different groups of CTV.

Results

Mean absorbed dose to the whole heart (MWHD) (1.9 vs. 2.1 Gy, P < 0.005), left anterior descending coronary artery mean dose (8.2 vs. 8.4 Gy, P < 0.005) and left ventricle (LV) mean dose (3.0 vs. 3.2, P < 0.005) were all significantly lower with 3D-CRT technique compared to t-IMRT. Apical (8.5 vs. 9.0, P < 0.005) and anterior LV walls (5.0 vs. 5.4 Gy, P < 0.005) received the highest mean dose (D_mean). MWHD and LV-D_mean increased with increasing CTV size regardless of the technique. Low MWHD values (< 2.5 Gy) were achieved in 44 (73.3%) and 41 (68.3%) patients for 3D-CRT and t-IMRT techniques, correspondingly.

Conclusions

Our study confirms a considerable range of the planned doses within the heart for adjuvant 3D-CRT or t-IMRT in node-negative breast cancer. We observed differences in heart dosimetric metrics between the three groups of CTV size, regardless of the radiotherapy planning technique.

Breast size impact on adjuvant radiotherapy adverse effects and dose parameters in treatment planning

Background Breast radiotherapy is an established adjuvant treatment after breast conserving surgery. One of the important individual factors affecting the final cosmetic outcome after radiation is breast size. The purpose of this review is to summarise the clinical toxicity profile of adjuvant radiotherapy in women with breasts of various sizes, and to evaluate the treatment planning studies comparing target coverage and dose to thoracic organs at risk in relation to breast size. Conclusions Inhomogeneity and excessive radiation dose (hot spots) in the planning of target volume as well as large volume of the breast per se, all contribute to a higher rate of acute adverse events and suboptimal final cosmetic outcome in adjuvant breast cancer radiotherapy, regardless of the fractionation schedule. Improved homogeneity leads to a lower rate of ≥ grade 2 toxicity and can be achieved with three-dimensional conformal or modulated radiotherapy techniques. There may be an association between body habitus (higher body mass index, bigger breast size, pendulous breast, and large chest wall separation) and a higher mean dose to the ipsilateral lung and whole heart. A combination of the technical innovations (i.e. the breath-hold technique, prone position with or without holding breath, lateral decubitus position, and thermoplastic bra), dose prescription (i.e. moderate hypofractionation), and irradiated volume (i.e. partial breast irradiation) should be tailored to every single patient in clinical practice to mitigate the risk of radiation adverse effects.

Novel Radiotherapy Techniques for Breast Cancer

During the early decades of radiation therapy for breast cancer, local control of disease was documented consistently but, enigmatically, an anticipated impact on breast cancer survival was not observed, leading to confusion in our understanding of the natural history of breast cancer and radiation effects. Now, almost 90 years after its first use in breast cancer, technology developments in diagnostic imaging and radiation therapy have elucidated parts of this enigma. The data now available demonstrate a significant impact of radiation therapy on survival as well as disease control and treatment-related mortality, opening a doorway to understanding the powerful impact of radiation therapy on both breast cancer and critical organs. Efforts are focused on leveraging novel techniques to maximize the benefits of radiation for breast cancer patients.

Lack of Prognostic Impact of Adjuvant Radiation on Oncologic Outcomes in Elderly Women with Breast Cancer

BACKGROUND

Radiotherapy plays an important role as adjuvant treatment in locally advanced breast cancer and in those patients who have undergone breast-conserving surgery. This study aimed to investigate the prognostic impact of adjuvant radiation on oncologic outcomes in elderly women with breast cancer.

MATERIALS AND METHODS

In this retrospective study, we reviewed and analyzed the characteristics, treatment outcome and survival of elderly women (aged ≥ 60 years) with breast cancer who were treated and followed-up between 1993 and 2014. The median follow up for the surviving patients was 38 (range 3-207) months.

RESULTS

One hundred and seventy-eight patients with a median age of 74 (range 60-95) years were enrolled in the study. Of the total, 60 patients received postoperative adjuvant radiation (radiation group) and the remaining 118 did not (control group). Patients in the radiation group were significantly younger than those in the control group (P value=0.004). In addition, patients in radiation group had higher node stage (P value<0.001) and disease stage (P=0.003) and tended to have higher tumor grade (P=0.031) and received more frequent (P value <0.001) adjuvant and neoadjuvant chemotherapy compared to those in the control group. There was no statistically significant difference between two groups regarding the local control, disease-free survival and overall survival rates.

CONCLUSIONS

In this study, we did not find a prognostic impact for adjuvant radiation on oncologic outcomes in elderly women with breast cancer.