Various forms of immunotherapy, such as checkpoint blockade immunotherapy, are proving to be effective at restoring T cell-mediated immune responses that can lead to marked and sustained clinical responses, but only in some patients and cancer types. Patients and tumours may respond unpredictably to immunotherapy partly owing to heterogeneity of the immune composition and phenotypic profiles of tumour-infiltrating lymphocytes (TILs) within individual tumours and between patients. Although there is evidence that tumour-mutation-derived neoantigen-specific T cells play a role in tumour control, in most cases the antigen specificities of phenotypically diverse tumour-infiltrating T cells are largely unknown. Here we show that human lung and colorectal cancer CD8 TILs can not only be specific for tumour antigens (for example, neoantigens), but also recognize a wide range of epitopes unrelated to cancer (such as those from Epstein-Barr virus, human cytomegalovirus or influenza virus). We found that these bystander CD8 TILs have diverse phenotypes that overlap with tumour-specific cells, but lack CD39 expression. In colorectal and lung tumours, the absence of CD39 in CD8 TILs defines populations that lack hallmarks of chronic antigen stimulation at the tumour site, supporting their classification as bystanders. Expression of CD39 varied markedly between patients, with some patients having predominantly CD39 CD8 TILs. Furthermore, frequencies of CD39 expression among CD8 TILs correlated with several important clinical parameters, such as the mutation status of lung tumour epidermal growth factor receptors. Our results demonstrate that not all tumour-infiltrating T cells are specific for tumour antigens, and suggest that measuring CD39 expression could be a straightforward way to quantify or isolate bystander T cells.

The consensus molecular subtype (CMS) classification of colorectal cancer is based on bulk transcriptomics. The underlying epithelial cell diversity remains unclear. We analyzed 373,058 single-cell transcriptomes from 63 patients, focusing on 49,155 epithelial cells. We identified a pervasive genetic and transcriptomic dichotomy of malignant cells, based on distinct gene expression, DNA copy number and gene regulatory network. We recapitulated these subtypes in bulk transcriptomes from 3,614 patients. The two intrinsic subtypes, iCMS2 and iCMS3, refine CMS. iCMS3 comprises microsatellite unstable (MSI-H) cancers and one-third of microsatellite-stable (MSS) tumors. iCMS3 MSS cancers are transcriptomically more similar to MSI-H cancers than to other MSS cancers. CMS4 cancers had either iCMS2 or iCMS3 epithelium; the latter had the worst prognosis. We defined the intrinsic epithelial axis of colorectal cancer and propose a refined ‘IMF’ classification with five subtypes, combining intrinsic epithelial subtype (I), microsatellite instability status (M) and fibrosis (F).

Recurrence after laparoscopic ventral rectopexy is multifactorial, and risk factors are both clinical and technical. The use of biologic grafts was associated with lower recurrence as compared with synthetic mesh. Patients with full-thickness rectal prolapse who are elderly, have poorer baseline continence, and have prolonged pudendal nerve terminal motor latency are at increased risk of recurrence.

Circulating tumour DNA (ctDNA) has the potential to be a specific biomarker for the monitoring of tumours in patients with colorectal cancer (CRC). Here, our aim was to develop a personalised surveillance strategy to monitor the clinical course of CRC after surgery. We developed patient-specific ctDNA assays based on multiplexed detection of somatic mutations identified from patient primary tumours, and applied them to detect ctDNA in 44 CRC patients, analysing a total of 260 plasma samples. We found that ctDNA detection correlated with clinical events – it is detectable in pre-operative but not post-operative plasma, and also in patients with recurrent CRC. We also detected ctDNA in 11 out of 15 cases at or before clinical or radiological recurrence of CRC, indicating the potential of our assay for early detection of metastasis. We further present data from a patient with multiple primary cancers to demonstrate the specificity of our assays to distinguish between CRC recurrence and a second primary cancer. Our approach can complement current methods for surveillance of CRC by adding an individualised biological component, allowing us not only to point to the presence of residual or recurrent disease, but also attribute it to the original cancer.

Laparoscopic surgery for colorectal cancer requires an abdominal incision to extract the resected specimen. We describe a technique for laparoscopic resection of an early-stage upper rectal cancer in a 51-year-old man followed by transanal specimen delivery, hence avoiding the need for making any additional abdominal incisions for retrieval of the specimen. Pneumoperitoneum was created, followed by medial-tolateral mobilization of the sigmoid colon, and take down of the splenic flexure and division of the inferior mesenteric vessels laparoscopically. The upper rectum distal to the tumour and proximal colon was transected with a laparoscopic stapler. The specimen was retrieved transanally via an opening in the rectal stump. The proximal colon was then delivered transanally and the anvil of the circular stapler inserted before returning it to the pelvic cavity. The rectal stump was transected again just below the opening to close off the stump, and the colorectal anastomosis was then completed intracorporeally. The patient, a 51-year-old male (BMI 18.6 kg/m(2)) with a 2.5-cm, early-stage posterior rectal cancer 12 cm from the anal verge, underwent the above-described procedure. Postoperative recovery was uneventful. He resumed normal daily activities 1 week after surgery. Histology confirmed a T1N0 upper rectal cancer. In the effort to minimize surgical trauma and postoperative pain, natural orifice specimen extraction techniques have been attempted. This procedure may be applicable to benign tumours and early colorectal cancer, and serves as an intermediate step between laparoscopic and natural orifice surgery.