A "cancer cluster," according to the Centers for Disease Control and Prevention, is "a greater-than-expected number of cancer cases that occurs within a group of people in a geographic area over a period of time." The CDC's Web page about clusters  notes that they may be difficult to define, that what might appear a cluster to some may subsequently be found to have explanations, and that identifying a cluster doesn't necessarily lead to a clear course of action.
That's all of little comfort if your colleagues keep getting diagnosed with breast cancer. Since 2000, eight professors and staff members have been diagnosed with breast cancer in the literature building at the University of California at San Diego, and two of the women have died. About 130 women worked in the building during the time period when the diagnoses started. A UCSD medical report last year found odds of 1 in 333 that chance alone could explain the incidence of breast cancer in the building.
In addition (and not counted in determining the 1 in 333 odds), individuals in the building have been diagnosed since 1997 with ovarian cancer, carcinoma of the adrenal cortex, adenoid cystic carcinoma of the salivary gland, and metastatic cervical cancer. Two women who work in the building have had large uterine masses and one a large ovarian mass -- although those were not malignant.
Nearly 1,000 people have signed a petition  demanding changes in the building to reduce risks that may be associated with cancer. Today, people who work in the building plan a walkout and to hold a teach-in about the cancer cluster.
While those organizing the rally maintain that the university has not done enough, UCSD officials are announcing new steps, including a decision to shut off an elevator some believe may be linked to the cancers.
Last year's medical report did not identify any certain feature of the building that could be definitively tied to the cancer cases. But the report suggests changes in the way the elevators are set up -- as key hydraulic elevator equipment is currently on the first floor and not in the basement, as would be common. The report noted that close exposure to surges associated with such equipment might add very modestly to the risk associated with breast cancer, and suggested changes in office locations -- and future building set-ups with elevators -- to minimize those risks.
While the report at length says that there is no sure link that could be found, it also advocates "prudent avoidance" of certain risks, even as they are still being studied. The report also finds no evidence that chemicals or mold in the building could be linked to the cancer cases.
A statement released by the university Monday said that officials "appreciate the concern" about the literature building, and noted last year's findings that did not identify a clear link between the building and the cancers. The university has hired Leeka Kheifets, a professor at UCLA and an expert on concerns similar to those that have been raised about the literature building, to lead a new study.
That project, which started last week, is expected to take a total of eight weeks. In the meantime, the university shut down the elevator and has agreed to empty offices around it, pending the outcome of the new study. University officials stressed that they are committed to identifying any health hazards faced by those work work in the building.
Oumelbanine Zhiri, a professor who is among those organizing today's protest, said that she doesn't dispute the university's contention that there has been no proof of causation to date. But she said that was the wrong standard and criticized the university for not acting sooner despite lacking definitive proof. "Such proof cannot be brought on such a small population, and one should follow the principle of prudent avoidance, to err on the side of caution to protect the health of the employees."
Some cancer cluster investigations never lead to a satisfactory finding. Last month, public health officials in Pennsylvania released a report finding no environmental link  to explain why recent former students at Susquehanna University had cancer rates that were 56 percent higher than that of the general Pennsylvania population.