There is good news and bad news on the front of the cancer war. Overall, cancer mortality rates are decreasing. Doctors are developing better treatments for many cancers, and several of the most common cancers are decreasing, especially lung cancer in white males.

That's the good news. Bad news comes in two forms. People who survive cancer treatments are still alive, which is good, but their health and happiness has been compromised significantly, especially for children suffering from childhood cancers. Their lives will rarely be fully recovered.

The other piece of bad news is that some cancers continue to increase in frequency. More... And increasingly science points to the fact that only genetic factors cause only a small percentage of cancers. In other words, "most cancer is made, not born."

Human epidemiological studies implicate several endocrine-disrupting compounds as risk factors for various cancers, for example, breast cancer. The mechanisms of action are not clear, and the results are not consistent. Nonetheless, given the inherent biases in epidemiological studies for finding false negatives in studies of EDCs, the accumulating data justify concern.

Two points are especially important to bear in mind. First, most studies have focused on a relatively small number of compounds, especially PCBs, DDT (and its metabolites, particularly DDE) and dioxin. Some commentators have argued that because PCBs and DDT show inconclusive links to breast cancer, that EDCs in general are not involved in cancer. That is obviously false logic, often promoted strongly by industry-funded scientists.

Second, literally no studies (as of August 2002) have performed the most crucial test of EDC involvement in cancer etiology: a prospective study of exposure in the womb or at other vulnerable stages in development in relation to risk, later in life, to cancers. Virtually all studies look at adult exposures and adult risk. Recent work with dioxin and breast cancer and with PCBs/DDE and breast cancer, illustrate the importance of this.

There is one additional important point to consider on breast cancer and DDE, the most common human metabolite of DDT. One established risk factor for breast cancer is life-time exposure to estrogen. DDE is an anti-androgen, not an estrogen. On this basis, DDE would not be expected to be a risk factor for breast cancer. More...

Some specific results:

Use of household pesticides elevates the risk of childhood leukemia. This association had been noted previously, but this new study (published in August 2002) strengthens the case both with improved methodology and also by showing that the window of greatest vulnerability is exposure in the womb. More...

A new study of women exposed to dioxin in the 1976 Seveso, Italy, chemical plant explosion finds an association between dioxin levels measured in serum taken immediately after the explosion and breast cancer risk over the next 20 years. This study is an important move toward the methodology that will be necessary to confirm or refute impacts on breast cancer risk of exposure during critical periods of development. More...

The Long Island Breast Cancer Study Project published results in July 2002 which report no association between breast cancer risk and several organochlorine contaminants measured at the time of diagnosis. Aspects of the study design severely limit the conclusions that can be drawn. More...

A 2001 review of breast cancer epidemiology concludes

• Only a small portion of breast cancer cases can be explained by known risk factors.
• "There is a crucial need to better define time windows of exposure. Vulnerability periods correspond to in utero life, as well as prepubertal period both for girls and boys. In women, perimenopause may also be particularly relevant." A number of studies indicate that conditions in utero can influence the risk of breast cancer later in life.

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