NEW YORK (Reuters Health) Dec 13 - Women treated for breast cancer with radiation, with or without chemotherapy, had more cognitive problems a few years later than women who'd never had cancer, a recent study showed.
Research suggests that some women experience mental haziness, dubbed "chemo brain," during and soon after chemotherapy. One recent study found changes in the activity of certain brain regions in women who'd undergone chemotherapy (see Reuters Health story of November 15, 2011).
But some authors have questioned whether those problems are due to the chemotherapy or to the cancer itself. In the new report, breast cancer survivors showed certain small mental deficits regardless of whether they'd had chemotherapy.
"It's a very, very subtle thing. We're not talking about patients becoming delirious, demented, amnesic," said Dr. Barbara Collins, a neuropsychologist who has studied chemotherapy-related cognitive changes at Ottawa Hospital in Ontario, Canada, but wasn't involved in the new study.
"We're talking about a group of people that are saying, 'I'm pretty much still able to function, but I find it harder...it doesn't come as easily, and I can't do as many things at the same time.'"
The current study involved 129 breast cancer survivors in their fifties, on average. About half had received radiation and chemotherapy; the others had radiation only.
Six months after finishing treatment, and another three years later, women took a range of thinking and memory tests. Their scores were compared to those of 184 matched controls who'd never had cancer.
One limitation of using tests to measure cognition is that it's not clear how exactly they apply to functioning in everyday life, Dr. Paul Jacobsen, from the Moffitt Cancer Center in Tampa, Florida, and his colleagues wrote November 15 online in Cancer. Also, the researchers didn't have information on women's cognitive status at baseline.
On three of five types of memory tests, patients and controls performed similarly. But on two, the patients' scores were noticeably lower.
At both six months and a few years after treatment, cancer survivors scored worse on tests of executive functioning. And compared to controls, women in both of the cancer groups had lower scores on tests of processing speed and concentration, by about one to three points on a scale where 50 is considered average.
On all measures of mental ability, patients scored similarly whether or not they'd had chemotherapy.
"People talk about 'chemo brain,' and there's sort of a general view that if people have cognitive problems after the cancer treatment, it must be due to the fact that they had chemotherapy," Dr. Jacobsen told Reuters Health.
"We provided the most definitive evidence to date to suspect it's not just chemotherapy that is contributing to cognitive problems after breast cancer."
What exactly might be the cause, or causes, is still up for debate.
"There is very likely something to do with having cancer that already affects your cognitive function," Dr. Collins said. "What is it? Could it be stress? Could it be anxiety? Could it be depression? That's a possibility."
It could also be that the immune system's response to cancer affects the brain, she added.
Dr. Collins said that most of the data still points to some mental effect of chemotherapy in certain patients -- but that small differences between treatment groups might have been missed in this analysis.
Still, she said, "We can't be too quick to conclude, even if we find some subtle things, that they're all due to the chemotherapy. We have to step very carefully here in terms of understanding what the real factors are."
Dr. Collins told Reuters Health that foggy thinking and memory after cancer treatment tends to improve over time.
SOURCE: bit.ly/un1Q8l