Table 10.

Short version: statements pertaining to other rare adenomatous polyposis syndrome

Statements	Level of evidence and agreement
OAPS.1A. Germline multigene panel testing should be considered in patients with >20 cumulative colorectal adenomas.	LE: low Agreement: 97% (SA 60%; A 37%; N 3%)
OAPS.1B. The threshold may be lowered to 10 cumulative adenomas if: Diagnosed under the age of 60, or Family history of polyposis or CRC, or Extra-colonic manifestations consistent with known polyposis syndromes	LE: low Agreement: 93% (SA 73%; A 20%; D 7%)
OAPS.1C. Germline multigene panel testing (for CRC and polyposis syndromes) should be undertaken in patients with gastrointestinal cancers presenting under the age of 50 years.	LE: low Agreement: 94% (SA 33%; A 61%; D 6%)
OAPS.1D. Somatic testing for APC mosaic mutations should be considered in unexplained polyposis patients fulfilling criteria from statements A and B.	LE: low Agreement: 94% (SA 38%; A 56%; D 6%)
OAPS.2A. In the case of autosomal recessive hereditary polyposis syndromes, testing should always be offered to siblings. Children should be tested when: the frequency of carriers of pathogenic variants in the corresponding gene is higher than 1 in 100 in the general population; parents are consanguineous; monoallelic alterations in the corresponding gene also cause increased risk of cancer (for example, MMR gene mutations in relative of CMMRD patients). In this last case, testing should be offered to all first-degree relatives followed by cascade testing.	LE: low Agreement: 90% (SA 57%; A 33%; N 10%)
OAPS.2B. In autosomal dominant polyposis syndromes, testing should be offered to all first-degree relatives followed by cascade testing.	LE: low Agreement: 97% (SA 72%; A 23%; N 3%)

A, agree; CMMRD, congenital mismatch repair deficiency; CRC, colorectal cancer; D, disagree; LE, level of evidence; MMR, mismatch repair; N, neutral; SA, strongly agree; SD, strongly disagree.