Treatment of localized rectal cancer in the Nordic countries-comparison of Nordic to Dutch, ESMO, and NCCN guidelines.

Rectal cancer treatment in Nordic countries has traditionally differed, especially regarding neoadjuvant treatment. The aim of this review is to give an overview of the current rectal cancer guidelines in the Nordics and compare these to international guidelines. Oncologists and colorectal surgeons from the Nordic countries (Denmark, Finland, Norway, and Sweden) and the Netherlands were invited to participate in this narrative review. Two consensus meetings were held to agree on the content.

All authors provided recommendations from their national guidelines. In addition, recommendations from the European Society of Medical Oncology (ESMO) and from the US National Comprehensive Cancer Network (NCCN) guidelines were extracted. Several differences between the included guidelines were identified. The radiological "sigmoid take-off" definition for the upper margin of the rectum has been adapted in Denmark and the Netherlands, whereas the other guidelines rely on distance from the anal verge on rigid sigmoidoscopy.

Indications for direct surgery vary considerably, where the NCCN guidelines recommend more aggressive neoadjuvant treatment, primarily total neoadjuvant therapy (TNT), the Nordic and European guidelines open for direct surgery more often, and reserve especially TNT for high-risk cases. European countries more often recommend short-course radiotherapy, whereas NCCN maintains chemoradiotherapy as the mainstay. Whereas intentional and opportunistic organ preservation is an established part of the Dutch, NCCN, and ESMO guidelines, its use is mostly restricted to clinical trials in the Nordics. The Nordics and the Netherlands are restrictive in terms of adjuvant treatment, which is frequently recommended in ESMO and NCCN.

Whereas neoadjuvant immunotherapy is recommended for mismatch repair-deficient/microsatellite instability-high (dMMR/MSI-H) rectal cancer in NCCN, this use is off-label in Europe and not routinely recommended. Although all guidelines rely on the same evidence, there are considerable differences, especially in the indications and type of oncologic treatment, both in the neoadjuvant and in the adjuvant setting.