Gaining a lot of weight after surviving breast cancer may carry risks

Survivors of breast cancer may want to watch their post-diagnosis weight -- a study finds that women who gain a large amount of weight may be at greater risk of cancer recurrence and death.

The study, being presented at the American Assn. for Cancer Research’s meeting this week in Orlando, Fla., followed breast-cancer survivors in three groups from the United States and one from China.

Women who gained 10% or more than their pre-diagnosis weight were 14% more likely to have the disease return compared with women whose weight stayed fairly steady, within 5% of their pre-diagnosis weight.

The risk went up for women who were thinner at diagnosis, with a body-mass index of below 25. If they gained 10% or more of their pre-diagnosis body weight, they were at 25% higher risk of death and had a greater danger of cancer recurrence.

Gaining a moderate amount of weight seemed to have no effect on the risk of cancer recurrence or death. Among the participants, 16% had a large weight gain. Among the women who gained a great amount of weight, 19% had a BMI under 25, and 11.1% had a BMI over 30.

“Most women are not gaining a large amount of weight following breast-cancer diagnosis,” said lead author Bette Caan in a news release. Caan, a senior research scientist at the Kaiser Permanente Division of Research in Oakland, Calif., added, “However, our analysis showed an association with poorer outcomes overall for those who do. ... Women tend to worry about gaining weight after a breast-cancer diagnosis. But it’s actually only the larger weight gains that increase the risk of poor outcomes.”