Once again problems have been identified in BreastScreen Aotearoa, New Zealand’s breast cancer screening programme.
An internal audit of initial mammograms by a concerned radiologist working in the Southern DHB’s BreastScreen HealthCare screening programme revealed that there had been a delay in diagnosis for as many as 28 women. The review of 134 mammography films taken between 2007 – 2010 on all women screened by BreastScreen HealthCare and subsequently diagnosed with breast cancer showed that the reading of the mammogram did not flag the existence of a possible malignancy in an unknown percentage of them.
As early signs of breast cancer are notoriously difficult to pickup, normal procedure is for two radiologists to independently examine each mammogram. The Ministry of Health’s chief medical officer, Dr Don Mackie, said on National Radio’s “Nine to Noon” on Thursday 15 March 2012 that the system “wraps around a series of double checks” in the breast cancer screening pathway.1
He also explained that regular audits of the breast cancer screening programme don’t look at the problem from this perspective. Regular reviews of performance focus on the interval cancer rate, which is a cancer that develops in the intervals between routine screening. Dr Mackie said that the interval cancer rate for breast cancer screening in New Zealand is comparable with Australia and the UK. However, whether this is true for BreastScreen HealthCare remains to be seen.
A “whole of system review” of BreastScreen HealthCare is now being undertaken, and the Southern District Health Board is contacting the women whose diagnosis was delayed, Dr Mackie said.
A front-page article in the New Zealand Herald quoted breast surgeon Dr Belinda Scott as saying it was preferable to diagnose breast cancer early rather than late, but “we don’t know whether it makes any difference … or not. Because all cancers are different in their grading and their aggressiveness, we don’t really know whether you are going to be making a difference to those women diagnosed later.”2
An article in the Otago Daily Times on 17 March 2012 raised additional concerns that the problem may be much bigger than first thought. The latest three-year audit of service performance for the three years to November 2011 is still in draft form, but it is believed to have raised concerns of further potential problems.3
The MOH is putting together a special team of epidemiologists, radiologists, and screening experts to review the service with the aim of having the team review other mammograms from 2007- 2010. Dr Mackie has admitted that one possible outcome is that a mass rescreening may be required. In the meantime, Counties Manukau DHB and Mid-Central DHB will be providing second reads of mammograms. Two radiologists would also be going to the Southern DHB to perform assessment clinics (when a woman is recalled after a mammogram) indefinitely.
As reported in the December 2011 issue of the AWHC’s newsletter there is considerable controversy internationally over the effectiveness of breast cancer screening, with intense debates about breast cancer screening occurring in the UK and in Scandinavian countries.4
In October 2011 the UK announced yet another review of its breast cancer screening programme. Professor Mike Richards, the national cancer director for England, announced in the British Medical Journal that he will lead the review and said he was taking the “current controversy very seriously.”5
A review of clinical trials involving a total of 600,000 women concluded it was “not clear whether screening does more good than harm.” It said that for every 2,000 women screened in a 10-year period, one life would be saved, 10 healthy women would have unnecessary treatment and at least 200 women would face psychological distress for many months because of false positive results.
It was acknowledged that “women need more accurate, evidence-based and clear information to be able to make an informed choice about breast screening.”5
- Don Mackie. Nine to Noon. 15 March 2012. National Radio .
- Martin Johnstone. Breast cancer results delay, New Zealand Herald, 15 March 2012.
- Lynda Williams: Mammography Wars, AWHC Newsletter December 2011
- Ananya Mandal: Breast cancer screening effectiveness under scrutiny yet again, News Medical, Oct 26 2011