OAKLAND, Calif. — Breast cancer survivors who experience large weight gain have an increased risk of death after diagnosis, according to research released Tuesday by scientists at the Kaiser Permanente Division of Research in Oakland, Calif.
Breast cancer survivors who experienced severe weight gain (10% or more over their pre-diagnosis weight) were 14% more likely to experience a cancer recurrence, compared with women whose weight remained stable (within 5% of pre-diagnosis weight) following diagnosis.
"Most women are not gaining a large amount of weight following breast cancer diagnosis," stated lead researcher Bette Caan, a senior research scientist at the Kaiser Permanente Division of Research. "However, our analysis showed an association with poorer outcomes overall for those who do."
Caan explained that moderate weight gain did not affect breast cancer outcomes. "Women tend to worry about gaining weight after a breast cancer diagnosis," she said. "But it's actually only the larger weight gains that increase the risk of poor outcomes."
Researchers also found that women who have large weight gains after diagnosis tend to be within normal weight ranges to begin with. In addition, the post-diagnosis effect of the weight gain tends to be greater for women who were originally thinner, they explained.
Women who were leaner to begin with at diagnosis (body mass index less than 25) and who later gained 10% or more, had a 25% higher risk of cancer death and also had a higher risk of recurrence, compared with women whose weight remained stable (within 5% of pre-diagnosis weight) following diagnosis.
Extreme weight gain occurred in 16% of women overall. Slightly more than 19% of women with a BMI less than 25 fell into the large weight gain category, but only 11.1% of women with a BMI greater than 30 fell into that category.
The study results are being presented at the American Association of Cancer Research 102nd meeting, which is being held this week in Orlando, Fla.