Breast cancer increases while experts disagree on causes – Debate in crisis say academics

In a continuing increase in breast cancer, one in nine women in the UK now risk contracting the disease during their lifetime.

Some scientists argue that the cause may be an increased exposure to a number of environmental chemicals, a claim taken up by campaigners in the US and the UK who urge the government to provide better health protection. However, whereas the UK government has been keen to engage people in debate about genetics, GM crops and mobile phone masts, some say it is less enthusiastic about debate on breast cancer, where the research is officially regarded as equivocal.

In recognition of the concern to raise the profile of citizens’ influence and expertise in the management and control of risk, the Economic and Social Research Council has sponsored a detailed investigation of the issues involved here. A research team led by Laura Potts, Reader in Public Health and Environment, York St. John College has undertaken a project (ESRC Report “Divided we stand: bridging differential understandings of environmental risk”) in which a number of interviews, focus groups and discussions with key people were set up. It organised three local hearings at which participants were asked to map any local environmental hazards, as has been done in the US. A national hearing staged at the House of Commons drew together public health practitioners, advocacy groups, activists, environmental and non-governmental officers, dissident scientists, women with experience of breast cancer, epidemiologists, research scientists and an MP.

“Opinions on the cause of the rise in breast cancer were divided,” Ms Potts says. “Most participants agreed that an explanation of the increased incidence and its highly complex origins were certainly needed but even on this there was no consensus.”

Theories about what might cause the disease tended to cite genetic factors, internal hormone factors such as HRT and the contraceptive pill, smoking, drinking, dairy products, plastics, pesticides and the relation between the immune system, stress and the environment. Difficulties in finding out what caused breast cancer were compounded by a lack of comparable studies and controls and differing interpretations of the same data.

The science of epidemiology, the study of the incidence and distribution of disease in populations, which would normally be looked on as a prime source of information, was regarded by some research participants as being unable to provide answers, with some epidemiologists speaking of leverage and power, and it being impossible to ask questions about suspected environmental hazards. Even the epidemiological studies that have been done may have been misfocussed. One research scientist interviewed said, “All the big, solid epidemiology studies we’ve got have all…been done on blood and they don’t show any association. But the few that have been done using breast tissue, breast fat, do show an association.”

At one hearing a research scientist asserted that there was a “public health cover-up on the existence of clusters” and a public health specialist interviewed similarly claimed that “when it comes to making a public statement, as with BSE, everyone gets behind the barricades and the line is agreed”.

Participants in the project were at variance regarding how available evidence might be translated into policy. Should governments act on the basis of a precautionary approach? Some scientists claimed there was adequate evidence but that policymakers and journal editors were frightened to act on what was known. Many professionals were concerned that involvement in controversial debate could compromise their professional and career prospects in terms of funding, promotion and professional acceptance.

One epidemiologist interviewed pointed out that governments had long failed to act on smoking, where the evidence was “grotesquely strong”. However the cancer professionals felt more powerful evidence was needed before any policy could be proposed, a view echoed in Westminster adjournment debate speeches.

Meanwhile, can the deliberate staging of dialogues like these improve mutual trust and establish greater consensus? “Yes,” Ms Potts says, “Provided it is realised that the key contention, from our research, is not who participates, but their positions in relation to the evidence they cite. If protecting the public health is the key concern, then it is imperative that we find common ground on which to build preventative policies.”