Impact of metastases on survival 75 CHAPTER 5 The surgical approach depended on the location and extent of the LRRC and was performed by experienced surgical oncologists. For the purpose of this study, we categorized the type of resectionas lowanterior resection, abdominoperineal resection, multivisceral resection or nonvisceral resection. Amultivisceral resectionwas defined as a resection including a resectionof the rectumand at least one pelvic organ/structure (i.e., bladder, prostate, vesicles, uterus, vagina, ovaries, sacrum). Anonvisceral resection was defined as a resection of the recurrence without resection of the rectum. In the case of involved or narrow resection margins and when deemed feasible, intraoperative radiotherapy (IORT; dose 10-12.5 Gy) was administered. IORT was delivered by electron beam radiotherapy. In earlier years this was delivered using an Elektra SL-25 linear accelerator (ElektraOncology Systems, Stockholm, Sweden). From 2016 onwards, IORT was delivered using a Mobetron 2000 linear accelerator (IntraOp Inc., Sunnyvale CA, USA). Treatment distant metastases The treatment strategy for synchronous metastases was determined in an MDT meeting. Liver metastases were treated with surgery, radiofrequency ablation or stereotactic radiotherapy, all performed in the referring or a partnering hospital. Lung metastases were treated with metastasectomy or stereotactic radiotherapy. Lung and liver metastases were treated either during the interval between neoadjuvant (chemo) radiotherapy and surgery or postoperatively. In the case of peritoneal metastases, cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) was performed simultaneously with the LRRC resection. Inguinal or para-aortic lymph node metastases were treated with a lymphadenectomy simultaneous with the LRRC resection if residual disease was suspected after neoadjuvant treatment. Follow-up Patients were followed up in the CZE or in the referring hospital, according to the patient’s preference. Follow-up was performed according to the Dutch guidelines for colorectal cancer and consisted of carcinoembryonic antigens measurements four times a year during the first 2 years and twice a year during years 3-5. Ultrasonography of the liver and chest radiography or a thoracoabdominal computed tomography scan was performed twice a year during the first 2 years and once a year thereafter. End-points and statistical analysis Continuous data were reported as median (interquartile range), and categorical data as count (percentage). To compare individual variables, the Mann-Whitney U and chisquared tests were performed as appropriate.
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