Managing supraclavicular disease from breast cancer with brachial plexus-sparing techniques using helical tomotherapy

Use of electronic portal images to evaluate setup error and intra-fraction motion during free-breathing breast IMRT treatment

Before delivering of intensity-modulated radiotherapy, kilo-voltage image-guidance radiotherapy is widely used in setup error correction and monitoring intra-fraction motion effectively. Accordingly, this study proposes and tests an image integration technique for observing intra-fraction motion during beam delivery, with the wider objective of reducing both image-guidance time and the dose delivered to normal breast tissue. The study sample comprised 33 female patients with breast cancer, and 241 sets of portal images acquired using a VARIAN aSi-1000 electronic portal imaging device. Motion amplitudes and vectors were collected and calculated separately by two senior therapists. The setup error in 3 axes was computed for every fraction, with average shifting for lateral, longitudinal and vertical direction was -0.3-mm ± 0.5, -0.1-mm ± 0.5 and -0.6-mm ± 1.6, with the average vector of setup error being 2.9-mm ± 1.4. The average intra-fraction motion for vertical direction was (A: -0.1-mm ± 1.0; B: -0.0 ± 1.1), for longitudinal was (A: -0.4-mm ± 1.7; B: 2.0 ± 1.1), and for lateral direction was (A: 0.3-mm ± 1.3; B: 0.2 ± 1.8). The average intra-fraction vector was 2.9-mm ± 1.3 for therapist A, and 3.4-mm ± 1.8 for therapist B. Offline Review commercial software was utilized for setup error and motion analysis, and data analysis and reliability testing were conducted with statistical package of the social sciences. Pearson correlations between the two therapists was moderate (0.59, p << 0.01), and the Cohen's kappa value for inter rater agreement between different evaluators was fair in the anterior-posterior direction (0.25, p << 0.01), with slight agreement in other two directions and vectors. The study presented efficient and dose reduction method to evaluate setup error and intra-fraction motion during breast intensity-modulated radiotherapy treatment.

Helical TomoTherapy for locally advanced or recurrent breast cancer

Purpose

We report our experience of using helical tomotherapy (HT) to treat large and irregular shaped loco-regional advanced breast cancer target volumes embracing various organs at risk.

Patients and methods

We retrospectively analyzed 26 patients treated for very large, irregular shaped breast cancers. Patients were treated either with the intent to achieve local control in a primary setting (n = 14) or in a reirradiation setting (n = 12). The recurrence group was heavily pretreated with systemic therapy. Tumors were characterized by wide infiltration of the skin, encompassing mostly a complete hemithorax. The primary group underwent irradiation of supraclavicular, infraclavicular, axillary and parasternal lymphonodal region. Radiotherapy was combined with chemotherapy (n = 11). We assessed the PTV volume and its craniocaudal extension, the dose to the organs at risk, acute toxicity and survival.

Results

Median PTV was 2276 cm³ (1476–6837 cm³) with a median cranio-caudal extension of 28 cm (15–52 cm). The median dose to PTV was 40 Gy (32–60Gy). HT could be carried out in all patients without interruption. The acute toxicities were mild to moderate. The median LRFS and OS after radiotherapy was 21 and 57 months for the primary group versus 10 and 11 months for the recurrence group. Median PFS was 18 months (primary group) and 7 months (recurrence group).

Conclusions

HT is feasible for advanced thorax embracing target volumes with acceptable acute toxicity. Both curative and palliative indications can be considered good indications based on treatment volume and anatomical constellation.

Dosimetric analysis of the brachial plexus among patients with breast cancer treated with post-mastectomy radiotherapy to the ipsilateral supraclavicular area: report of 3 cases of radiation-induced brachial plexus neuropathy

Background

The purpose of this study was to evaluate the brachial plexus (BP) dose of postmastectomy radiotherapy (PMRT) to the ipsilateral supraclavicular (ISCL) area, and report the characteristics of radiation-induced brachial plexus neuropathy (RIBPN).

Methods

The BP dose of 31 patients who received adjuvant PMRT to the ISCL area and chest wall using three-dimensional conformal radiotherapy (3DCRT) and the records of 3 patients with RIBPN were retrospectively analyzed based on the standardized Radiation Therapy Oncology Group-endorsed guidelines. The total dose to the ISCL area and chest wall was 50 Gy in 25 fractions.

Results

Patients with a higher number of removed lymph nodes (RLNs) had a higher risk of RIBPN (hazard ratio [HR]: 1.189, 95% confidence interval [CI]: 1.005-1.406, p = 0.044). In 31 patients treated with 3DCRT, the mean dose to the BP without irradiation to the ISCL area was significantly less than that with irradiation to the ISCL area (0.97 ± 0.20 vs. 44.39 ± 4.13 Gy, t = 136.75, p <0.001). In the 3DCRT plans with irradiation to the ISCL area and chest wall, the maximum dose to the BP was negatively correlated with age (r = −0.40, p = 0.026), body mass index (BMI) (r = −0.44, p = 0.014), and body weight (r = −0.45, p = 0.011). Symptoms of the 3 patients with RIBPN occurred 37–65 months after radiotherapy, and included progressive upper extremity numbness, pain, and motor disturbance. After treatment, 1 patient was stable, and the other 2 patients’ symptoms worsened.

Conclusions

The incidence of RIBPN was higher in patients with a higher number of RLNs after PMRT. The dose to the BP is primarily from irradiation of the ISCL area, and is higher in slim and young patients. Prevention should be the main focus of managing RIBPN, and the BP should be considered an organ-at-risk when designing a radiotherapy plan for the ISCL area.