Margriet Kwint

Chapter 3 54 of the metastasis was the brain (42%) followed by bone (30%) and adrenal glands (18%). A mutation analysis was not mandated at the time of diagnosis in our institute. Therefore, Epidermal Growth Factor Receptor (EGFR) was only determined in 57% of the cases. In 11 patients (21%) an EGFR mutation was found. Other mutations were not analyzed since they were reported in a small minority of patients, and no statically power remained to test for this subgroup analysis. Treatment of the primary tumor consisted of (chemo) radiation (N= 81, 89%) in most patients. The other patients had a surgical intervention (N= 8, 9%) and 2 patients (2%) had no local treatment except systemic therapy. One of these 2 patients had an occult primary tumor and the other patient had a complete response of the primary tumor after targeted therapy. Seventy-five patients (82%) received systemic treatment ( Table 2 ). Nine patients (10%) received concurrent chemo- radiotherapy and 60 patients (66%) received sequential chemo- radiotherapy. Six patients (7%) received targeted therapy. The fractionation schedule for the radiotherapy was determined by a team of radiation oncologists, with the aim to achieve a radical regime. The most frequently used radiotherapy schedules were 24x2.75 Gy (48%), followed by 17x3 Gy (26%) and in 13% of the patients the primary tumor was treated with an ablative stereotactic radiotherapy schedule. Stereotactic radiotherapy to the lung tumor was chosen if the tumor was located peripheral (< 5 cm) and there were no lymph nodes involved (N0 disease). For 78 patients (86%) who received thoracic radiotherapy for the primary tumor in our institute (3 patients received the radiotherapy in another institute), the mean Gross Tumor Volume (GTV) for the primary tumor was: 71.2 +/- 114, 0 cm³ (min/ max: 0.3 - 741,5 cm³) (median 28.5 cm³). The mean total GTV (primary including lymph nodes) was 83.8 +/- 117.8 cm³ (min/max: 1.4 – 741.5 cm³) (median 45.8 cm³). Further treatment characteristics of the treatment of the primary tumor and lymph nodes are shown in Table 2 . In 48% of the patients, the metastases were treated with stereotactic radiotherapy. In 22% of the patients the metastases were in close proximity of the primary tumor or pathological lymph nodes and irradiated within the thoracic radiotherapy field (for example a rib metastasis or neck/axillary lymph nodes). Treatment modality for the brain metastases (surgery or stereotactic radiotherapy) was discussed and approved in a neuro-oncology tumor board.