CERVICAL CANCER STUDY: THE LEGACY OF NATIONAL WOMEN’S UNFORTUNATE EXPERIMENT
A New Zealand study reported in the Lancet Oncology in April 2008 revealed that between 31–50% of women with untreated CIN3, a precancerous disease of the cervix, will develop cervical or vaginal cancer over 30 years.
The study’s results are based on an independent analysis by a team of medical experts at Otago University of a clinical study of the natural history of CIN3 carried out by Dr Herbert Green at National Women’s Hospital during the 1960s and 1970s. The team led by Dr Margaret McCredie analysed the data compiled by Dr Green and confirmed that there is a high risk of cervical cancer in women not treated after finding precursor lesions, and a very low risk in women who received conventional treatment.
Dr Green’s clinical study was the subject of the judicial inquiry in 1987 now known as the Cartwright Inquiry. The Inquiry found that the study was unethical because treatment was withheld without consent, monitoring of outcomes was inadequate, and the study was not ended when clinicians raised their concerns. One of Judge Silvia Cartwright’s recommendations was that the material should be made available for research.
The records of 1229 women were analysed and it was found that among the 143 women who received only a diagnostic punch or wedge biopsy, 31% developed cervical cancer after 30 years. In the subset of 92 women who had persistent disease within 24 months of the original diagnostic biopsy, 50% developed cervical cancer after 30 years. These estimates took into account later treatments for many of the women.
Among the 593 women who received conventional treatment – usually by a cone biopsy or a hysterectomy – and treatment for recurrent abnormalities, the risk of invasive cancer was about 1% over the same period.
This latest study extends the earlier analysis by Dr Bill McIndoe and colleagues which was published in 1984. Professor Ron Jones, who instigated the current study and was involved in the earlier analysis, said “The present study has employed different methods of analysis and the follow-up has been extended to 30 years. However the findings are very similar to those reported by our group 24 years ago. Whereas in the original study we assessed the risk of cancer as 25 times greater in women with in-adequately treated CIN3, compared to treated women, the present estimates are even higher.”
An article that appeared in the NZ Herald referred to Dr Green’s study as one of the most vilified pieces of research in New Zealand. It has now given the world its most valid estimates yet of the risk of the precursor lesions known as carcinoma in situ or CIN 3 developing into cervical cancer.
As the publication of this paper occurred just before the 20th anniversary of the release of the Cartwright Report on 5 August 1988, it's appearance was very timely.