By Sue Rochman
How Much Are We at Risk?
By Sue Rochman
Oncologists are only now seeing the extent of the late effects in people who were treated for cancer 30 or more years ago. They have no way of knowing, though, what the risks will be for the patients who are being treated today, with new treatment regimens that include lower doses of certain chemotherapy drugs or smaller radiation fields. And by the time we do know, treatments will undoubtedly have changed again, with the aim of reducing late effects even further.
“I always tell people to keep in mind that the statistics we have for radiation-induced second cancers are based on patients who were treated a long time ago using outdated radiation treatment,” says Andrea Ng, a radiation oncologist at the Dana-Farber Cancer Institute, in Boston. “And that because our technology has evolved in the last few decades, the risk today is not necessarily the same.”
But what the exact risk is, be it for second cancers or other problems, is hard to say. Joseph Carver, an oncologic cardiologist at the University of Pennsylvania’s Abramson Cancer Center, in Philadelphia, notes that while he can tell patients who need an anthracycline or radiation therapy that their risk for cardiovascular disease is lower than for previous generations of patients, “we can’t say what that risk is. The only thing we can say for sure is that there is a risk and that it probably increases over time.”
It is especially difficult for researchers to assess the risk of late-term effects from cancer treatments in patients who are older, since they are at risk of health problems simply by virtue of their age. “We have 2.5 million breast cancer survivors and their average age at diagnosis was 61,” says Patricia Ganz, an oncologist at the Jonsson Comprehensive Cancer Center at the University of California, Los Angeles. “That means it’s hard to sort out what problems are from the treatment.” In contrast, she says, “if you are giving chemotherapy and radiation to a patient who is 35, and at age 50 they start to develop heart problems that they are too young to otherwise have, you know it’s more likely due to treatment.”
The question of how pervasive late effects are is especially important right now in the breast cancer field, because chemotherapy is being used increasingly in patients whose disease has not spread to their lymph nodes. In these women with early-stage disease, says Ganz, “you are trading a small amount of benefit for potential long-term toxicity.” It’s also possible that “you could be adding harm without adding value.”
