Hyperplastic polyposis in the New Zealand population: a condition associated with increased colorectal cancer risk and European ancestry.

AIM: The hyperplastic polyposis syndrome (HPS) has been described in a subset of patients with multiple or large hyperplastic polyps. HPS is associated with an increased risk of colorectal cancer (CRC). In this report, we review the presentation and management of a series of individuals with HPS.
METHODS: From 2001, gastroenterologists, surgeons, and histopathologists at Middlemore Hospital were asked to report cases of HPS. Clinical records were retrospectively reviewed to confirm the number and size of polyps and the age at diagnosis, site of involvement in the colon, and nature of surgical procedures performed in cases with CRC.
RESULTS: HPS was identified in 24 patients: 14 females and 10 males. Though 46% of patients attending our gastroenterology department are non-Europeans, all HPS cases had European ancestry. A family history of CRC was identified in four patients (16.6%). All patients had small polyps (<5mm) however 15 (63%) had at least one polyp > or =10 mm, the largest being 45 mm. There were 21 CRCs in 14 patients with a mean age at diagnosis of 61 years. The tumour site was known in 19 CRC, and 16 of these (84%) occurred in the proximal colon. Synchronous cancers were identified in four patients and metachronous tumours in two patients. Twenty-two surgical procedures were performed in 17 patients. Three patients underwent prophylactic surgery due to polyp burden or dysplasia.
CONCLUSION: HPS is rarely encountered but is associated with a significant risk of CRC and is found in the European component of the New Zealand population. Identification of this syndrome has implications regarding management and surveillance for both the individual patient and their first-degree relatives.