From the Director's Desk
Health Policy in theFace of Scientific Debate
We’ve seen some startling resistance to the California EPA’s declaration of secondhand smoke as a toxic air contaminant. CalEPA’s January 26 announcement cited causal associations between secondhand smoke exposure and respiratory illness, lung cancer, and heart disease. In particular, the report pointed to a causal link between secondhand smoke and breast cancer in younger, pre-menopausal women.
Leading agencies including the American Cancer Society, the Centers for Disease Control, and the US Department of Health and Human Services have publicly refused to support CalEPA’s declaration, generally citing a lack of “broad scientific consensus.” This has angered breast cancer advocates who feel that the evidence is strong enough to take action.
From a scientific standpoint, the resistance is understandable—scientific rigor demands substantial and conclusive evidence, exceptional statistical significance, and consistent results across several studies when determining cause and effect. In addition, it requires analysis, debate, and eventual agreement amongst a critical mass of scientific experts. To bypass this path to scientific certainty would lead us astray as many isolated research findings have failed to hold up to this scrutiny. It can also lead advocates to apply pressure for action prematurely.
In the 1990s, thousands of women underwent high-dose chemotherapy and bone marrow/peripheral blood stem cell transplants to treat metastatic or high-risk breast cancer in light of indirect evidence that it would increase their chance of survival. The results of large clinical trials demonstrating the lack of efficacy of this treatment did not become available until 2000.
In 1994, a large, well-designed study was released reporting that abortion increased the risk of breast cancer later in life by 50%. Subsequent studies failed to verify this finding, but the National Cancer Institute was pressured by legislators and advocacy groups to modify its language about abortion in its breast cancer fact sheet. In February, 2003, the National Cancer Institute convened a workshop of over 100 scientific experts that concluded that having an abortion does not increase a woman’s subsequent risk of developing breast cancer and the information on the NCI website was revised. A search of the web today, however, reveals numerous websites dedicated to “exposing” the risk between abortion and breast cancer and calling for legislation to require this risk in informed consent for those undergoing abortions.
On the other hand, to ignore research findings and fail to take action while we await scientific certainty can delay life-saving interventions. We all cope daily with Health Policy in the Face of Scientific Debate circumstances in which we must make decisions in the absence of absolute certainty—health policy is no different. How much certainty we require before taking action is a matter of common sense and personal and collective judgment.
It DOES matter if breast
cancer is related
Does it matter whether or not breast
cancer is linked to active or passive
smoke exposure? Don’t we know
enough about the harmful effects of
smoking and secondhand smoke to
call for eliminating these toxins from
our environment? On a public health
and pragmatic level, the link to breast
cancer does matter. While the morbidity
and mortality from heart and lung
diseases (all firmly connected to smoke
exposure) far outnumbers the morbidity
and mortality from breast cancer, it has
been well-documented that women are
much more afraid of breast cancer (and
therefore perhaps more motivated to
take action to avoid it) than they are of
heart and lung disease. Thus, establishment
of a link between secondhand
smoke and breast cancer may create a
more powerful public will to eliminate
exposure. A similar argument led to the
CBCRP funding research on the link
between the spread of breast cancer
to the lungs and smoking in 2001
(see Smoking Effect on Pulmonary
Metastasis from Breast Cancer in the
research portfolio on our website). This study provided direct, experimental
evidence that exposure to cigarette
smoke is associated with an increase
in the spread of cancer cells to the
lung and highlights the need for
smoking cessation efforts directed at
women, particularly those at increased
risk of breast cancer.
There is uncertainty
So why has the CalEPA’s determination
of secondhand smoke as a toxic
air contaminant caused such a stir?
One reason is that the link between
secondhand smoke and breast cancer
is not yet widely accepted. Decades
can elapse between exposure to a
toxin and a cancer diagnosis, and we
suspect that timing of the exposure at adolescence, for example can
also
make a significant difference in one’s
later risk of a cancer diagnosis. The
data that informed CalEPA’s decision
didn’t arise from thin air. Previous research
has indicated that active smoking
actually decreased risk of breast
cancer, but the assessment of active
and passive smoke exposure in these
studies was in most cases not strong.
Growing evidence supports the possible
link between active smoking and
exposure to secondhand smoke and a
woman’s increased risk of pre-menopausal
breast cancer.
We still have to make decisions
While it may take years to unravel the
many different threads of related factors
and influences to establish scientific
certainty, common sense argues
that this is one risk factor that we, as
individuals and as a society, can control.
Add to this the strong evidence
linking secondhand smoke to cardiovascular
disease, respiratory illness
and other cancers, and the rationale
for reducing exposure is strong.
Another area in which there is a great deal of scientific uncertainty is the link between breast cancer and environmental agents. The Special Research Initiatives, which was initiated last year by the California Breast Cancer Research Program, is in the process of developing a comprehensive examination of the evidence that links environmental hazards to the increased risk of breast cancer occurrence. This review will serve as a springboard to targeted research strategies that we hope will increase scientific certainty. It is our goal to identify more ways that Californians can protect themselves from controllable risks.
Marion H. E. Kavanaugh-Lynch, M.D., M.P.H.,
Director of the CBCRP
