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Trends in colorectal cancer incidence rates in New Zealand, 1981–2004
Author(s) -
Shah Ankit B.,
Sarfati Diana,
Blakely Tony,
Atkinson June,
Dennett Elizabeth R.
Publication year - 2012
Publication title -
anz journal of surgery
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.426
H-Index - 70
eISSN - 1445-2197
pISSN - 1445-1433
DOI - 10.1111/j.1445-2197.2011.05995.x
Subject(s) - medicine , colorectal cancer , incidence (geometry) , rectum , descending colon , sigmoid colon , cecum , splenic flexure , cancer , gastroenterology , oncology , demography , colonoscopy , physics , sociology , optics
Background: Incidence rates of colorectal cancer (CRC) in New Zealand rank among the highest worldwide. Internationally, there has been evidence of a shift in colon cancer from left‐ to right‐sided. The objective of this study was to determine trends in left‐ and right‐sided colon and rectal cancers incidence by sex, age and ethnicity. Methods: Using datasets created by linking data from the New Zealand Cancer Registry to the census data, we analysed a total of 47 694 CRCs from 1981 to 2004. Cancers were divided into right‐sided colon (cecum to the splenic flexure); left‐sided colon (descending and sigmoid colon); and rectal (rectosigmoid junction and rectum). Results: Left‐ and right‐sided colon, and rectal cancer incidence rates increased by 13–20% among men. In women, colon cancer rates increased by 25% for right‐sided cancers, decreased by 8% for left‐sided cancers and remained unchanged for rectal cancers. This corresponds with an increase in right‐sided cancers from 57% to 65% of total colon cancers in women. The incidence of all CRCs increased at a faster rate among Māori than non‐Māori. Conclusion: We identified a left‐ to right‐sided shift in colon cancer limited to women over the age of 65. While Māori trends in site distribution parallel those of their non‐Māori counterparts, the rapid increase in Māori incidence rates is noteworthy. It is unclear why such shifts in CRC site distribution are occurring.