Non-coplanar volumetric modulated arc therapy for locoregional radiotherapy of left-sided breast cancer including internal mammary nodes

Background Non-coplanar volumetric modulated arc therapy (ncVMAT) is proposed to reduce toxicity in heart and lungs for locoregional radiotherapy of left-sided breast cancer, including internal mammary nodes (IMN). Patients and methods This retrospective study included 10 patients with left-sided breast cancer who underwent locoregional radiotherapy after breast-conserving surgery. For each patient, the ncVMAT plan was designed with four partial arcs comprising two coplanar arcs and two non-coplanar arcs, with a couch rotating to 90°. The prescribed dose was normalized to cover 95% of planning target volume (PTV), with 50 Gy delivered in 25 fractions. For each ncVMAT plan, dosimetric parameters were compared with the coplanar volumetric modulated arc therapy (coV-MAT) plan. Results T here were improvements in conformity index, homogeneity index and V55 of total target volume (PTVall) comparing ncVMAT to coVMAT (p < 0.001). Among the organs at risk, the average V30, V20, V10, V5, and mean dose (Dmean) of the heart decreased significantly (p < 0.001). Furthermore, ncVMAT significantly reduced the mean V20, V10, V5, and Dmean of left lung and the mean V10 and V5 and Dmean of contralateral lung (p < 0.001). An improved sparing of the left anterior descending coronary artery and right breast were also observed with ncVMAT (p < 0.001). Conclusions Compared to coVMAT, ncVMAT provides improved conformity and homogeneity of whole P TV, better dose sparing of the heart, bilateral lungs, left anterior descending coronary artery (LAD), and right breast for locoregional radiotherapy of left-sided breast cancer with IMN, potentially reducing the risk of normal tissue damage.

A case of contralateral inguinal lymph node metastases from breast cancer

Background Breast cancer is well known to tends to invade through the lymphatic chains mainly to the axillary and subclavian nodes or occasionally to the internal mammary nodes. However, inguinal lymph node metastasis from breast cancer is extremely rare. Case presentation We have experienced a case of an 82-year-old woman showing left inguinal lymph node metastases from right breast cancer. Previously, she had received five times abdominal operations and left artificial bone head replacement for metamorphous hip-joint disease. Although the metastases were firstly detected 46 months after the breast surgery, they had already existed at the time of the breast operation, which was retrospectively re-evaluated by CT examination. The progression pattern of inguinal lymph node metastases had much correlated with that of the breast cancer. She underwent inguinal lymph node dissections. Pathological findings revealed them being compatible with breast cancer origin. Conclusions This is the sixth case having been reported in English literature. Besides, this is the first case showing the contralateral spread to the primary breast cancer. One of the causes of this complex metastatic pattern is thought be ascribed to the previously performed prolific abdominal operations.

Reproducibility of Repeated Breathhold and Impact of Breathhold Failure in Whole Breast and Regional Nodal Irradiation in Prone Crawl Position

In whole breast and regional nodal irradiation (WB + RNI), breathhold increases organ at risk (OAR) sparing. WB + RNI is usually performed in supine position, because positioning materials obstruct beam paths in prone position. Recent advancements allow prone WB + RNI (pWB + RNI) with increased sparing of OARs compared to supine WB + RNI. We evaluate positional and dosimetrical impact of repeated breathhold (RBH) and failure to breathhold (FTBH) in pWB + RNI. Twenty left-sided breast cancer patients were scanned twice in breathhold (baseline and RBH) and once free breathing (i.e. FTBH). Positional impact was evaluated using overlap index (OI) and Dice similarity coefficient (DSC). Dosimetrical impact was assessed by beam transposition from the baseline plan. Mean OI and DSC ranges were 0.01–0.98 and 0.01–0.92 for FTBH, and 0.73–1 and 0.69–1 for RBH. Dosimetric impact of RBH was negligible. FTBH significantly decreased minimal dose to CTV WBI, level II and the internal mammary nodes, with adequate mean doses. FTBH significantly increased heart, LAD, left lung and esophagus dose. OI and DSC for RBH and FTBH show reproducible large ROI positions. Small ROIs show poor overlap. FTBH maintained adequate target coverage but increased heart, LAD, ipsilateral lung and esophagus dose. RBH is a robust technique in pWB + RNI.

Non-coplanar VMAT improves plan quality for locoregional radiotherapy of left-sided breast cancer with internal mammary nodes

Purpose A planning study was performed to evaluate the feasibility of non-coplanar volume modulated arc therapy (ncVMAT) for locoregional radiotherapy of left-sided breast cancer with internal mammary nodes. Methods and materials Ten patients with left-sided breast cancer after breast conserving surgery were retrospectively studied. The planning target volumes (PTV) were contoured encompassing the whole breast/chestwall, internal mammary nodes (IMN) and supraclavicular nodal (SCN) region. For each patient, ncVMAT plan with 4 partial arcs composing of two coplanar arcs and two non-coplanar arcs with couch rotating to 90˚ was generated. The prescription dose was normalized to cover 95% of PTV with 50 Gy delivering in 25 fractions. For each ncVMAT plan, dosimetric parameters were compared with coplanar VMAT (coVMAT) plan optimizing with identical coplanar beam angle arrangement. Results With ncVMAT, the mean conformity index of the whole PTV increased from 0.82±0.02 to 0.86±0.01 (p=0.005), and there was no significant difference for the homogeneity index. The mean coverage of internal mammary target volume (PTVimn) with ncVMAT increased from 88.77±3.07% to 91.67±3.84% comparing with coVMAT (p=0.005). Meanwhile, the V55 in PTVscn and PTVimn decreased significantly from 5.76±6.03%, 13.73±7.77% to 2.94±3.93%, 3.75±3.36%, separately (p<0.01). For organs at risk, the average V30, V20, V10, V5 and Dmean of heart decreased from 5.13±3.22%, 12.18±7.29%, 33.98±15.73%, 72.03±16.79% and 10.47±2.97 Gy to 4.86±2.54%, 9.35±5.43%, 25.16±12.42%, 62.27±13.18% and 9.08±2.34 Gy, separately (p<0.01). Furthermore, ncVMAT significantly reduced the mean V20, V10, V5, Dmean of left lung, and V10, V5, Dmean of contralateral lung (p<0.01). A better sparing of LAD descending coronary artery and right breast were also shown with ncVMAT (p<0.01). Conclusions Compared to coVMAT, ncVMAT provides better conformity, lower V55 in PTVscn and PTVimn, better coverage of PTVimn, better dose sparing in heart, bilateral lung, LAD and right breast for locoregional radiotherapy of left-sided breast cancer with internal mammary nodes, which potentially increase the local control in IMN and reduce the risk of deleterious effects.