Two out of three women who have had breast cancer report putting on weight after their diagnosis, gaining on average 9kg, an Australian study shows.

Nearly one in five of the women who put on weight gained more than 20kg, in the first national survey of weight after breast cancer.

Sydney GP and lead author Dr Carolyn Ee said the findings highlighted the importance of GPs in helping the women to manage lifestyle factors.

“As well as significant weight gain, we also found high levels of concern about weight among our survey participants,” adding that timing was key in addressing the problem.