Anastomotic leak is a subject close to the heart of colorectal surgeons, particularly as it can have devastating effects on patients. We know that early recognition and early source control are key to ensuring the best outcome after anastomotic leak.

A multicentre cohort study of serum and peritoneal biomarkers to predict anastomotic leakage after rectal cancer resection
Sparreboom et al Colorectal Dis 2020 22: 36-45

This study is a multicentre cohort which looks at a range of biomarkers to detect anastomotic leak following rectal resection by day 3. The biomarkers were taken from blood (CRP) or from drain fluid (MMP, and interleukins). The authors undertook logistic regression and found that Matrixmetalloprotease 2 (MMP2) and CRP rises were associated with anastomotic leak.

This fits with the rest of the literature. CRP (or the change in CRP) is constantly revisited as a detector of anastomotic leak, with varying degrees of success. MMP is an enzyme which is known to degrade extracellular matrices, leading to anastomotic breakdown. The presence of this protein may be linked to the microbiome (i.e. bacterial product).

A few caveats with this paper. With 38 events, a regression model including 12 explanatory variables may be too many to detect all effects (rule of thumb is 5-10 events per variable). This means that some markers may have been erroneously discounted. The calibration of the model also seems to have been performed on the dataset it was derived from. This will always fit reasonably well, so external validation is required. There is also the question of how to implement this into practice. Most UK surgeons will not use drains following an anterior resection, so testing for MMP by this route is not an option.

This paper of the month focuses on female sexual function following radiotherapy for rectal cancer.

Effect of Radiotherapy for Rectal Cancer on Female Sexual Function: A Prospective Cohort Study
Rojvall et al Br J Surg 2019 Dec 3 [Online ahead of print]

Functional outcomes following rectal cancer surgery are relatively understudied when compared to oncological outcomes. However, these are important as they are the after effects the patient has to live with.

This is a prospective cohort from Sweden, and recruited women with stage I-III rectal cancers. Sexual function was assessed using the Female Sexual Function Index (FSFI) at baseline, 1 year, and two years. There was also an assessment of ovarian reserve in women under the age of 45.

The study recruited 139 patients, of whom 109 had pre-operative radiotherapy. There was fairly minimal drop out. Women in the no-radiotherapy group were typically older and had lower FSFI scores at baseline (ie worse function). The authors use a regression analysis to show that deterioration in FSFI score over 2 years after is associated with pre-operative radiotherapy, increasing age, and not having a partner at baseline.

This study is interesting because it does show a decline in FSFI in the study population. There are some differences between the pre-op radiotherapy and the non-preop radiotherapy groups which might make comparison difficult. The sample size may be a bit on the small side for the type of analysis undertaken, which is reflected in the broad confidence intervals seen for some of the variables (narrow interval = well sampled = better estimate). The study also has a high number of APER and pre-operative radiotherapy, perhaps reflecting a more tertiary practice than typically seen. I do wonder if a third comparison group of similarly aged women without rectal cancer might also have been a useful comparison. Finally, whilst the FSFI is a validated tool, it has some characteristics that might impair its use in this setting.

This study does provide useful information for counselling patients, and should inform future study designs.