Surgical treatment of benign colorectal polyps 2008–21

Discussion

Our results show that 2.1 % of patients diagnosed with benign polyps during the study period underwent surgery. The figures varied from 2.0 % in 2008 to 1.6 % in 2021. Despite the slight reduction in the rate of surgical procedures, the total number of surgeries is going up due to the rise in diagnosed cases. Approximately 90 % of colorectal polyps are small and can be easily removed endoscopically (11). The remainder are complex (large polyps that are technically challenging to remove endoscopically) and require a higher level of endoscopic competence. A meta-analysis of 49 studies showed that 97.3 % of complex polyps are successfully treated using endoscopic methods (12, 13). Based on these figures, only 0.3 % of all benign colorectal polyps will require surgery, assuming that there is access to adequate endoscopic expertise. An incidence of surgery of 2.1 % can therefore be regarded as too high.

Surgical resection of benign polyps leads to higher rates of complication and mortality, without improving treatment effectiveness (6–8, 14, 15). Furthermore, endoscopic methods reduce the risk of severe late complications after surgical resection (16).

If a malignant polyp requiring completion surgery is treated endoscopically first, this does not result in a poorer prognosis for the patient (17).

Our results are supported by studies from the United States and the Netherlands (18, 19). Various factors could explain the high incidence of surgical treatment. Studies show that the main factors for surgical treatment are polyp size > 20 mm, polyp in the right colon, high-grade dysplasia and sessile morphology (15, 20). These studies indicate that the endoscopist's competence and decisions impact on how many patients with benign polyps are referred for surgery. Furthermore, research shows that the inclusion of polypectomy experts in interdisciplinary polyp discussions on treatment options can reduce overtreatment of benign polyps (21–23). Two Norwegian studies have documented the need to increase competence in endoscopic polyp treatment in Norway (24, 25). In order to improve competence, the Norwegian Endoscopy School initiated polypectomy training for endoscopists in 2020, and interdisciplinary polyp discussion groups were recently established in Western Norway Regional Health Authority and South-Eastern Norway Regional Health Authority (26).

In order for colorectal cancer screening to reduce the incidence and mortality of the disease, preventing surgical overtreatment of benign polyps is crucial (2, 5). A Danish study suggests that the benefits of colorectal cancer screening may be negated by the increased mortality associated with surgical complications (27).

One of the requirements of the colorectal cancer screening programme is that a plan must be in place to manage complex polyps (28), but it is up to the individual health authorities to determine how such competence should be developed and maintained (28).

Our results show a high incidence of surgery for benign polyps, and this has financial ramifications. Endoscopic methods reduce bed days, sick leave, complication rates, long-term morbidity and loss of future capacity to work (29–31). In the United States, the estimated cost of surgical treatment for a benign polyp is approximately NOK 230 000 per patient (29, 31), compared to NOK 80 000 for endoscopic treatment (29, 31).

In our study, mean bed days after surgery for benign polyps have been reduced from more than twelve days (2008) to less than eight days (2021). However, compared to endoscopic treatment, which is mostly performed on an outpatient basis, the number of bed days remains high. In 2019, the mean cost of one bed day in a Norwegian hospital was NOK 18 175 (32). The 4566 patients in our study had a total of 53 242 bed days, giving a bed-day cost of over NOK 970 million (in 2019 kroner), which corresponds to NOK 69 million per year. Our study also shows an increase in colonoscopy activity during the study period (from 44 326 colonoscopies in 2008 to 90 158 in 2021). Colonoscopy activity, and thus also the number of diagnosed polyps, is set to increase further due to the introduction of colorectal cancer screening. If the incidence of surgery for benign polyps is not reduced, increased colonoscopy activity will significantly compromise health economics.

Endoscopic examination waiting lists, a shortage of available expertise and long travel times to a unit with the necessary expertise can all lead to patients being referred for surgery for benign polyps. A lack of DRG (diagnosis-related group) points for endoscopic polypectomy and thus underfunding of endoscopic treatment can also be a factor (33).

In our study, we used statistics from the NPR, which has near complete coverage for procedures performed in Norway. Our data source contains publicly accessible statistics in Norway that are used for research, quality measurements and decision-making. However, it is possible that diagnostic codes are less precise than procedure codes and that polyps may be miscoded in our data sources, with invasive cancer lesions incorrectly being coded as benign polyps. If incorrect coding has occurred, we see no reason why the proportion of miscoding would differ across the various regional health authorities or over time during the study period.

Some patients may have additional indications for surgery, such as other intestinal cancers, hereditary polyposis syndromes or inflammatory bowel disease. Nevertheless, this applies to only a small number of patients, and the proportion is likely to remain constant over time. Finally, we must consider the fact that some surgeries may have been performed after unsuccessful attempts at endoscopic treatment or as a result of complications from endoscopic treatment.