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Aim Positron emission tomography (PET)/CT can be used to monitor the metabolic changes that occur after intensified treatment with induction chemotherapy and chemo(re)irradiation for locally recurrent rectal cancer (LRRC). This study aimed to analyse the correlation between the PET/CT response and final histopathological outcomes. Methods All LRRC patients who underwent induction chemotherapy prior to surgery between January 2010 and July 2020 and were monitored with pretreatment and post-treatment PET/CT were included. Visual qualitative analysis was performed, and patients were scored as having achieved a complete metabolic response (CMR), partial metabolic response (PMR) or no response (NR). The histopathological response was assessed according to the Mandard tumour regression (TRG) score and categorized as major (TRG 1-2), partial (TRG 3) or poor (TRG 4-5). The PET/CT and TRG categories were compared, and possible confounders were analysed. Results A total of 106 patients were eligible for analysis; 24 (23%) had a CMR, 54 (51%) had a PMR and 28 (26%) had NR. PET/CT response was a significant predictor of the negative resection margin rate, achieving 96% for CMR, 69% for PMR and 50% for NR. The overall accuracy between PET score and pathological TRG was 45%, and the positive predictive value for CMR was 63%. A longer interval between post-treatment PET/CT and surgery negatively influenced the predictive value. Conclusion Metabolic PET/CT response evaluation after neoadjuvant treatment proves to be a complementary diagnostic tool to standard MRI in assessing tumour response, and may play a role for treatment planning in LRRC patients.

Background The optimal treatment for patients with locally recurrent rectal cancer (LRRC) is controversial. The aim of this study was to investigate different treatment strategies in two leading tertiary referral hospitals in Europe. Methods All patients who underwent curative surgery for LRRC between January 2003 and December 2017 in Catharina Hospital, Eindhoven, the Netherlands (CHE), or Karolinska University Hospital, Stockholm, Sweden (KAR), were studied retrospectively. Available MRIs were reviewed to obtain a uniform staging for optimal comparison of both cohorts. The main outcomes studied were overall survival (OS), local re-recurrence-free survival (LRFS), and metastasis-free survival (MFS). Results In total, 377 patients were included, of whom 126 and 251 patients came from KAR and CHE respectively. At 5 years, the LRFS rate was 62.3 per cent in KAR versus 42.3 per cent in CHE (P = 0.017), whereas OS and MFS were similar. A clear surgical resection margin (R0) was the strongest prognostic factor for survival, with a hazard ratio of 2.23 (95 per cent c.i. 1.74 to 2.86; P < 0.001), 3.96 (2.87 to 5.47; P < 0.001), and 2.00 (1.48 to 2.69; P < 0.001) for OS, LRFS, and MFS respectively. KAR performed more extensive operations, resulting in more R0 resections than in CHE (76.2 versus 61.4 per cent; P = 0.004), whereas CHE relied more on neoadjuvant treatment and intraoperative radiotherapy, to reduce the morbidity of multivisceral resections (P < 0.001). Conclusion In radiotherapy-naive patients, neoadjuvant full-course chemoradiation confers the best oncological outcome. However, neoadjuvant therapy does not diminish the need for extended radical surgery to increase R0 resection rates.

Lateral nodal disease is of major importance in the treatment of rectal cancer in the East, but a mostly neglected entity in the West. In this article, the treatment of recurrences in the lateral compartment (latLRs) in a national tertiary referral center is evaluated. Of 214 patients with locally recurrent rectal cancer who underwent multimodality treatment in the Catharina Hospital in the last 10 years, a total of 51 patients with latLR were selected (the latLR region was classified as upper, middle, or lower). Thirteen (25 %) of these patients underwent induction chemotherapy (ICT) prior to chemo(re)irradiation. LatLRs occurred mainly after low and N+ primary tumors. Seven (14 %) patients had a complete response (pCR) and 28 (55 %) underwent an R0 resection. Patients with a lower latLR had the highest chance of undergoing an abdominoperineal resection and resection of anterior organs. ICT resulted in a 31 % pCR rate compared with 8 % without ICT (p = 0.039). Patients who received ICT had an 85 % R0 resection rate, while this was 45 % in patients who did not receive ICT (p = 0.013). The 5-year local re-recurrence (LRR) rate was 64.3 %, and overall survival (OS) was 34.2 %; the only factor improving these was an R0 resection. Five-year survival after multivariate analyses was 10.3 % after an R+ resection compared with 66.8 % after an R0 resection (p = 0.011). LatLRs impose a major surgical challenge and result in high LRR and low OS. More R0 resections can possibly be achieved with ICT, which is the only factor that can improve LRR and OS.