M. Walser

Long term outcomes of patients with skull-base low-grade chondrosarcoma and chordoma patients treated with pencil beam scanning proton therapy

PURPOSE To evaluate the long term tumor control and toxicity of skull base tumors treated with pencil beam scanning proton therapy (PT). MATERIALS AND METHODS PT was delivered to 151 (68%) and 71 (32%) chordoma and chondrosarcoma (ChSa) patients, respectively. Mean age of patients was 40.8±18.4years and the male to female ratio was 0.53. The postoperative tumor was abutting the brainstem or optic apparatus in 71 (32.0%) patients. The postoperative mean gross tumor volume (GTV) was 35.7±29.1cm(3). The delivered mean PT dose was 72.5±2.2GyRBE. RESULTS After a mean follow-up of 50 (range, 4-176) months, 35 local (15.8%) failures were observed between 10.9 and 85.4months. The estimated 7-year LC rate for chordoma (70.9%; CI95% 61.5-81.8) was significantly lower compared to the LC rate for ChSa patients (93.6%; 95%CI 87.8-99.9; P=0.014). The estimated 7-year distant metastasis-free- and overall survival rate was 91.6% (95%CI 91.6-98.6) and 81.7% (95%CI 74.7-89.5), respectively. On multivariate analysis, optic apparatus and/or brainstem compression, histology and GTV were independent prognostic factors for LC and OS. The 7-year high grade toxicity-free survival was 87.2 (95%CI 82.4-92.3). CONCLUSIONS PBS PT is an effective treatment for skull base tumors with acceptable late toxicity. Optic apparatus and/or brainstem compression, histology and GTV allow independent prediction of the risk of local failure and death in skull base tumor patients.

Radiation exposure of the heart, lung and skin by radiation therapy for breast cancer: A dosimetric comparison between partial breast irradiation using multicatheter brachytherapy and whole breast teletherapy

BACKGROUND AND PURPOSE Accelerated partial breast irradiation by means of multicatheter brachytherapy shows great promise in the modern treatment of early breast cancer combining high efficacy in preventing tumour recurrence with low levels of toxicity. The present work attempts a dosimetric comparison between this treatment modality and conventional whole breast external beam radiotherapy by looking at differences in risk organ exposure to radiation. PATIENTS AND METHODS The planning CT data sets of 16 consecutive patients with left-sided breast cancer who received external beam radiotherapy to the whole breast followed by a boost to the tumour bed using multicatheter interstitial brachytherapy after breast conserving surgery were used to create two independent physical treatment plans - one for an external radiotherapy, one for sole partial breast brachytherapy in each case assuming a total reference dose of 50Gy for each patient. Dose-volume parameters D(0.1cc), D(0.5cc), D(1cc,)D(2cc), D(5cc,)D(10cc), D(25cc), D(50cc), V(100), V(90), V(50), V(10), V(5) for the ipsilateral lung, the heart and the adjacent skin were calculated and compared between the two treatment modalities. RESULTS All organs at risk showed a substantially lower radiation exposure in the brachytherapy plan. This was most pronounced for the heart with values differing by a factor of four. Although somewhat less marked this was also true for the ipsilateral lung and the adjacent skin with exposure ratios of three and two, respectively. CONCLUSIONS With the use of multicatheter interstitial brachytherapy substantial reductions in the radiation exposure of risk organs can be achieved in comparison to whole breast external beam radiotherapy. These are likely to translate into profound clinical benefits.

Tumour control and Quality of Life in children with rhabdomyosarcoma treated with pencil beam scanning proton therapy.

PURPOSE To assess clinical outcomes in children with rhabdomyosarcoma (RMS) treated with pencil beam scanning (PBS) proton therapy (PT). METHODS AND MATERIALS Eighty-three RMS (embryonal, n=74; 89%) patients treated between January 2000 and December 2014 were included. The median age was 4.5years (range, 0.8-15.5). All patients received systemic chemotherapy according to prospective protocols. Patients had low-, intermediate-, and high-risk disease in 24%, 63%, and 13% of cases, respectively. The median total dose delivered was 54Gy(RBE) (range, 41.4-64.8). RESULTS After a median follow-up time of 55.5 months (range, 0.9-126.3), local failure occurred in 16 patients. The 5-year local-control survival rate was 78.5% [95% confidence interval (CI), 69.5-88.5%]. Significant predictors for local failure were group/stage, tumour location, and size. Fourteen patients (16%) died, all from tumour progression. The 5-year overall survival was 80.6% (95%CI, 71.8-90.0%). The 5-year incidence of grade 3 non-ocular late toxicity was 3.6% (95%CI, 1-12%). No grade 4-5 late toxicities were observed. One radiation-induced malignancy was observed (1.2%). The Quality of Life (QoL) scores increased significantly after PT compared to baseline values. CONCLUSIONS PBS PT led to excellent outcome in children with RMS. Late non-ocular toxicity was minimal and QoL good.

Long term outcome of skull-base chondrosarcoma patients treated with high-dose proton therapy with or without conventional radiation therapy

BACKGROUND AND PURPOSE Skull-base chondrosarcoma (ChSa) is a rare bone tumor and the outcome of patients with this malignancy has been documented only in a limited number of series with a restricted number of patients. OBJECTIVE This study was conducted to assess the outcome and prognostic factors of a large cohort of ChSa patients treated with radiotherapy in two proton therapy centers. MATERIALS AND METHODS From 1996 to 2015, 251 (male, 43.4%) patients (mean age, 42.0 ± 16.2 years) were treated with protons with (n = 135; 53.8%) or without photons (n = 116; 46.2%). Median delivered dose was 70.2 GyRBE. Failure-free survival (FFS), overall survival (OS) and CTCAE grade ≥3 toxicity free survival (TFS) were calculated using the Kaplan-Meier method. RESULTS After a median follow-up of 88.0 months for surviving patients, local and distant failures were observed in 12 (4.8%) and 4 (1.6%) patients, respectively. Late failures >6 years were observed in 4 (33.3%) patients. The estimated 7-year FFS was 93.1%. Twenty-five (10%) patients died. The estimated 7-year OS was 93.6%. Tumor volume (p = 0.006) and optic pathway compression (p = 0.027) were significantly associated with the risk of treatment failure on univariate analysis. Treatment failure was significantly associated with a higher risk of death (hazard ratio = 126). The estimated 7-year TFS was 84.2%. CONCLUSIONS The outcome of skull-base ChSa patients treated with high-dose protons with or without photons is excellent, particularly for patients with small tumors with no optic pathway compression. Treatment failure was however associated with a significantly increased risk of death.