br Corresponding author Department of Surgery V astmanland s
* Corresponding author. Department of Surgery, V€astmanland's Hospital V€asterås, SE-72189, V€asterås, Sweden.
E-mail address: [email protected] (I. Sverrisson).
anastomotic leakage (AL), pelvic abscesses and deep perineal wound infections [14e16]. Increased surgical complications after surgery for rectal cancer in patients who were previously treated with high-dose RT for prostate cancer has been reported in two small cohort studies that included 20 patients in total [17,18]. The selection of a proper treatment strategy for this DMOG patient cohort is a clinical challenge and requires thorough consideration. Access to two nationwide registries, the Swedish Colorectal Cancer Registry (SCRCR)  and the National Prostate Cancer Register (NPCR) , allowed us to address the treatment strategies in these patients. The aim of this study was to assess the AL rate after anterior resection (AR) in patients with rectal cancer who had previously received RT for prostate cancer.
Materials and methods
All hospitals in Sweden (approximately 10 million inhabitants)
treating patients with colorectal cancer and prostate cancer report clinical, surgical, pathological and follow-up data to the SCRCR and NPCR, respectively. In 2010, the NPCR was linked to a number of other population-based registries in Sweden, which resulted in the creation of the Prostate Cancer Database Sweden (PCBaSe) . All men included in the SCRCR who had undergone bowel resection because of rectal cancer between 2000 and 2016 and were treated with RT for prostate cancer before the diagnosis of rectal cancer were identified in the PCBaSe. The men included in this study consisted of two groups: men who underwent bowel resection for rectal cancer and had previously received RT for prostate cancer (RT-prost) and patients who underwent bowel resection for rectal cancer after pre-operative RT with or without a previous diagnosis of prostate cancer without receiving RT for prostate cancer (RT-rect).
Rectal cancer was defined in the SCRCR as an adenocarcinoma of the rectum located within 15 cm from the anal verge. Prostate cancer was defined as a malignant tumour of the prostate. The most common pre-operative RT regime for rectal cancer during the study period was short-course RT (5 Gy five times over 1 week), followed by immediate surgery. If a concomitant chemotherapy (CRT) regime was needed, a long course of RT (1.8e2 Gy for 25e28 days over 6e8 weeks) was delivered with chemotherapy. The most common curative RT regime for prostate cancer was external brachytherapy with a total dose of 78e80 Gy using 2 Gy/fraction.
To assess the level of transection of the rectum and the anas-tomoses, we looked at the height of the tumour from the anus. In patients requiring AR with a partial mesorectal excision (PME), transection 5 cm distal to the tumour is recommended according to the Swedish national guidelines. If the tumour was located 10 cm or less from the anus, we classified the operation as a low AR with TME, which is defined as a transection of the rectum below the peritoneal reflection, just above the levator ani.
To ensure that all anastomotic complications were recorded in patients with rectal cancer undergoing an anterior resection who
had previously received RT for prostate cancer, their medical re-cords were reviewed and the presence of AL up to 90 days after the operation was graded according to the International Study Group of Rectal Cancer (ISGRC). The ISGRC defines an AL as a defect of the intestinal wall at the anastomotic site leading to a communication between the intra- and extra-luminal compartments. Grade A AL requires no active therapeutic intervention; grade B requires active therapeutic intervention, but is manageable without re-laparotomy; and grade C requires re-laparotomy . The overall post-operative complications were graded according to the ClavieneDindo classification .