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Guest blog: “Are you a gambler or an accountant?”

Authors: E Back, J Häggström, K Holmgren, M M Haapamäki, P Matthiessen, J Rutegård, M Rutegård
Casio Calculator

Permanent stoma rates after anterior resection for rectal cancer

Anterior resection for rectal cancer is a beautiful operation. Whether with hand-held electrocautery or robotic scissors, uncovering the mesorectal package in embryological planes is a most satisfying moment, especially when followed up by a nice, tension-free and well-perfused anastomosis; when all goes well, of course. Unfortunately, anastomotic breakdown is a far too common and dangerous event, tripling the risk of early death1. Quite often, such an event also leads to reoperation and a permanent stoma2. No wonder then that, after decades of research on the merits of defunctioning stomas preventing anastomotic leakage3, there’s a near ubiquitous use in low anterior resection4 (though recent reports challenge this dogma5). The caveat, it seems, is that even temporary stomas cause problems6 and might never be reversed7, questioning the sphincter-saving procedure itself. Moreover, the spectre of severe low anterior resection syndrome rears its ugly head even when a textbook outcome is accomplished8; on the other hand, quality of life might be worse for patients with a permanent stoma9, and this was reported even in the stoma-friendly Scandinavian environment.

The problem is insurmountable, it seems. Do you choose bowel dysfunction and the risk of a leak, or do you opt for a permanent stoma at the get go? Would you dare omit the defunctioning stoma? In short, are you a gambler or an accountant?

In any case, information on an individual patient level is sorely needed for such an important discussion. We’ve recently published a prediction study using pre-operative variables collected from the Swedish Colorectal Cancer Registry, where an attempt has been made at forecasting the risk of a permanent stoma at two years after anterior resection for rectal cancer. While close to five thousand patients contributed data in the analysis, using the ensemble method SuperLearner to develop and validate a moderately accurate prediction model, the real thrust from this study lies in the on-line calculator. The input is shown in Figure 1, where the key predictors can be varied to reflect the patient at hand.

Figure 1. Variables included in the logistic forward-backward selection model can be varied, reflecting the individual patient.

There are certainly more variables of importance out there, and the experienced surgeon will surely add some data to a mental recalculation; smoking, on-going inflammation, continuous immunosuppressive medication, as well as a weak sphincter might decrease the chances of a stoma-free outcome even more. The output can be seen in Figure 2, where the risk of a permanent stoma is depicted in a cross-tabulation of defunctioning stoma use and laparoscopy use; those factors are the only ones that can be altered at a preoperative consultation. Importantly, the output is a predicted risk with measures of uncertainty, providing lower and upper bounds of the permanent stoma risk. Consistently, there is a higher risk of a permanent stoma with the use of a defunctioning stoma, which recently was shown using mediation analysis4.

Figure 2. Output from the prediction model with corresponding measures of uncertainty.

We urge all fellow surgeons to play around with the calculator – it’s actually quite addictive. Perhaps it can be informative in a patient-centred approach to anterior resection, as it seems that, stoma avoidance has the same priority as cure of cancer in some patient populations10. While at it, we can also recommend the internationally validated prediction model for low anterior resection syndrome, POLARS11. While all these prediction models can be improved, it is certainly worthwhile for both surgeon and patient to have some idea of the expected results after anterior resection. 


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