Breast cancer screening does save lives after all, according to a paper in the Lancet which supporters of the NHS programme hailed as an end to two years of heated controversy.
Two studies, in January 2000 and then October last year, carried out by Ole Olsen and Peter Gotzsche from the Nordic Cochrane centre in Copenhagen and also published in the Lancet, came to the conclusion that breast cancer screening had been oversold, and worse, that it could even do harm. Their analysis of the seven main trials carried out in Sweden, Scotland, the US and Canada, concluded that there was no sound evidence that lives were saved.
Most trials were of poor quality, they said. The two that were of medium quality failed to show any effect on death rates. Survival rates had gone up, but much of that was due to better treatment. Screening could do harm, they said, because it led to women having mastectomies when slow growing tumours were spotted that "would never have developed into cancer in the women's remaining lifetimes".
The furore has undermined the confidence of some women in breast screening and has caused ructions in the US. The physicians data query board - expert advisors - told the National Cancer Institute in January that "mammography may not be beneficial". Shortly afterwards, the American Medical Association and the American Cancer Society were among 10 signatories to a full page advertisement in the New York Times urging women to go for screening.
The paper published today is a response to Olsen and Gotzsche. It was applauded yesterday by the coordinator of the NHS breast screening programme and is likely to be backed by the World Health Organisation which will be releasing the findings of an investigation into the screening controversy on Monday.
Lennarth Nystrom from the department of health and clinical medicine at Umea University and colleagues found there was a "modest" benefit from breast screening in women over the age of 55, although not before.
They sought to answer the criticisms of the Cochrane scientists by updating the Swedish trials. They followed up the 247,000 women in the trials by looking for deaths from breast cancer recorded in the Swedish cancer and cause of death registers up to 1996.
They found there were 511 breast cancer deaths in 1,864, 770 years of life among women who were screened and 584 breast cancer deaths in 1,688, 440 years of life among those women who were not.
This, they said, showed screening reduced the death rate by 21%. The benefits were greatest for women aged 60-69 when they entered the trial.
In a commentary in the journal, Karen Gelmon from the British Columbia cancer agency, Vancouver, Canada, writes: "These data confirm that women who are otherwise well, especially those aged 55-69 years, and who are concerned about breast cancer, should be encouraged to attend screening. Partly because of the controversy around mammography, less than half of such women, the age group most likely to benefit, access this service on a regular basis in many western countries."
Julietta Patnick, national coordinator of the NHS cancer screening programmes, said: "While the full benefits of the NHS breast screening programme will not be evident until the end of the decade, this paper corroborates our premise that breast screening saves lives."
