Seven New Zealand regions have bowel cancer rates statistically above the national average. Four of these are in the North Island.

South Canterbury has the highest rate in new data, released today and covering 2009 to 2013, at 113 patients per 100,000 people. It is followed by Wairarapa, Otago-Southland (Southern District Health Board), Nelson Marlborough, Bay of Plenty, Taranaki and Hawkes Bay.

When the data is adjusted to remove the effect of varying age structures between regions -- bowel cancer risk increases with age -- South Canterbury and Otago-Southland, remained above average.

The data is published by the Health Quality and Safety Commission in its online Atlas of Healthcare Variation. Such atlases serve to highlight differences in health and treatment by region, age, ethnicity and other factors. The aim is to prompt probing on why differences exist and if they can be avoided.


Bowel cancer is the most commonly reported cancer in New Zealand, with around 3000 new cases and 1200 deaths each year.

The Government is planning a national bowel cancer screening programme -- a staged expansion of the pilot programme at the Waitemata District health Board -- but the national scheme will invite participation from a narrower age range of people, 60-74, than at the Waitemata pilot, where the range is 50 to 74.

The data release follows the publication last year of a wide-ranging analysis of bowel-cancer incidence and treatment by cancer specialists Professor Michael Findlay and Dr Christopher Jackson and colleagues in the so-called "Piper" study.

The commission said its data showed two-thirds of people were alive two years after being diagnosed with bowel cancer.

There was up to a two-fold variation between DHBs for survival at three months after surgery. And there was wide variation between DHBs in the use of radiotherapy before surgery for people with rectal cancer.

"While these findings may be affected by missing private-hospital data the results are generally very similar to those recently reported by the Piper study."

The commission made comparisons with British data which, like Piper, suggested delays exist in diagnosis in New Zealanders.

"More people with bowel cancer were diagnosed after a visit to an emergency department in New Zealand, 27 per cent, than in England and Wales, 20 per cent."


However, overall survival at two years -- 67 per cent -- was the same for New Zealand, and England and Wales.

The charity Bowel Cancer NZ, which said it had been calling for greater transparency, welcomed the commission's data release.

The Atlas made many of the variations visible and would allow communities and healthcare providers to consider and address the possible reasons.

"In a country like New Zealand, our ethnicity and the places where we live should not result in different access to diagnosis, treatment or survival," said the charity's spokeswoman, Sarah Derrett.

The organisation said that of immediate concern were the higher proportions of Maori, 28 per cent, and Pacific people, 25 per cent, who had more advanced bowel cancer at diagnosis than the overall rate of 21 per cent; and also the higher Maori rate of diagnosis at an emergency department, 39 per cent, and the Pacific rate, 41 per cent, compared with the overall rate of 27 per cent.

"Late diagnosis and where cancer has spread from the bowel to other parts of the body means that survival rates are worse," Ms Derrett said.