You have heard about cancer clusters before. If you are buying a new home, you will avoid an area known for high cancer levels, if avoidance is possible. Of course, the fact that an area has gained that reputation does not in fact mean that a real cancer cluster exists.

Simply because a lot of people have cancer in a particular neighborhood does not mean that the neighborhood suffers from a cancer cluster. It might, but much more information is needed to know one way or the other.

If you throw dice on the table 1000 times, you might hit the same combination several times in a row, on a few different occasions. Several runs with the same numeric combination might be statistically normal - not the sign of an unusual event. Or, not the sign of a "cluster."

For years, Long Island, New York has been mentioned as a possible high breast cancer area. The National Cancer Institute has investigated the area, and the results are, as you might imagine, mixed.

Yes, some of the well-known breast cancer risk factors were confirmed in the study. These risk factors included increasing age, having a family history of breast cancer, having a first child at a later age (age 28 or older in this study), never having given birth to a child, and having higher income. The income thing always puzzles me.

However, other usual cancer causing suspects were not associated with having caused cancer in this study. They included early age at beginning of menstruation and having attained a higher level of education (so you can be smart, but not too rich).

There were also studies of organochlorine compounds, specifically of the pesticide DDT. The researchers anticipated that they would find a causal connection between DDT exposure and increased rates of breast cancer. In this study, no general increase of this nature was confirmed.

However, the researchers suggested that a higher breast cancer risk in some individuals may be associated with organochlorine exposures because of individual differences in metabolism and ability to repair DNA damage. Further research is planned to explore this. But so far, the Long Island study is not suggesting a general relationship between increased exposure and increased risk of breast cancer. That is big news.

One chemical exposure was found to be related to breast cancer. Exposure to PAHs, which have long been considered to be cancer causing, was linked to increased chances of contracting breast cancer. This is found in tar residue, and has historically been associated with the coal gasification process (the manner in which natural gas used to be made before transcontinental pipelines existed.) Women who had the highest levels of exposure had a what was termed a "modest" 50 percent increased risk for breast cancer.

I thought it was interesting that a 50% increased risk was termed "modest." It does not seem modest to me. But the NCI observes that compared to other known risk factors for cancer, a 50 percent increase is modest. Smoking, for example, results is a nearly 1000 % increase in risk of contacting lung cancer. Nonetheless, I still believe that a 50% increase is sizable.

For those women who live in Long Island, this information is helpful because it verifies that some causal relationships do exist. Hopefully, this will result in additional funding and assistance for those who are ill. It may also lead to research that will keep others healthy.

However, it seems to be that so many questions remain unanswered. The biggest question is this: what should women who live in possible cancer cluster areas do? Need they avoid anything? Need they change their routines. Need they seek medical evaluations more frequently that women who live elsewhere? Certainly, increased medical monitoring makes sense to me.

Published: August 22, 2002

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