"Hot flashes a common curse in menopause can be especially bothersome after breast cancer. But a new study suggests an existing medication may help. The drug is oxybutynin Ditropan XL long used to treat urinary incontinence. The study found that women taking the medicine had an average of five fewer hot flashes a week compared with three fewer among women taking a placebo.  Oxybutynin is an option that can control these symptoms and improve quality of life said lead researcher Dr. Roberto LeonFerre an assistant professor of oncology at the Mayo Clinic in Rochester Minn. There are a couple of reasons for severe hot flashes after breast cancer. Chemotherapy may induce early menopause and drugs that reduce estrogen levels may make hot flashes worse the research team noted.  Hormone replacement therapy which is often recommended for menopausal symptoms is generally not advised for breast cancer survivors. Thats left women who cant take hormones at a disadvantage. Oxybutynin blocks a substance in the brain and one of its side effects is decreased sweating LeonFerre noted.  Because of this we can take advantage of the side effect and decrease involuntary sweating associated with hot flashes and decrease the hot flashes as well he explained. The drug could be gamechanging for certain women said Dr. Alice Police regional director of breast surgery at Northwell Health Cancer Institute in Sleepy Hollow N.Y. This is a really important advance in survivorship and compassionate cancer care added Police who wasnt involved in the study. Because oxybutynin is already available for other conditions LeonFerre said doctors could prescribe it offlabel. However he cautioned that its longterm effects arent known. Drugs in this class  called anticholinergics  have been linked with mental decline he said.  For example the drugs may raise the risk for problems with shortterm memory reasoning and confusion and may also hike the risk for dementia among older patients studies indicate. For the new study LeonFerre and his colleagues randomly assigned  women who experienced at least  hot flashes a week to oxybutynin or a placebo.  Almost twothirds were also taking drugs to prevent a return of breast cancer either tamoxifen or an aromatase inhibitor. The women were randomly assigned to one of three groups lowdose oxybutynin twice a day for six weeks lowdose oxybutynin for one week followed by an increased dose or a placebo.  Both doses appeared to reduce hot flashes better than the placebo. And oxybutynin doesnt interfere with the metabolism of tamoxifen LeonFerre said calling that an important consideration for breast cancer survivors. Most insurance covers oxybutynin and a months supply can range from  to . With insurance copays would be less he added.  Side effects included constipation mild diarrhea dry mouth dry eyes episodes of confusion and difficulty urinating the researchers found.  Women taking oxybutynin also reported improvement in work social activities leisure activities sleep and overall quality of life. These are vital issues Police said. I will never forget the first time a patient said Thank you for curing my breast cancer but you ruined my life  she said. The patient said endocrine therapy had caused hot flashes so severe that she could not sleep. As a result she was having trouble at work and in all other aspects of her life Police recalled. Her intimate relationship was also suffering as nighttime had become a battleground between her and her internal temperature control Police said.  The patient said she was willing to stop her hormone therapy and risk the return of breast cancer rather than live with her current symptoms she said. This study makes me hopeful that these patients may have a way out of their dilemma Police said. Instead of just telling them they should be happy to be alive we may be able to offer a reliable treatment for some of the debilitating side effects of our treatments for breast cancer.  The research was scheduled to be presented Friday at the San Antonio Breast Cancer Symposium in Texas. Studies presented at meetings are usually considered preliminary until peerreviewed for publication in a medical journal. More information The U.S. National Cancer Institute has more about hot flashes and cancer survivors https SOURCES Roberto LeonFerre M.D. assistant professor oncology Mayo Clinic Rochester Minn. Alice Police M.D. regional director breast surgery Northwell Health Cancer Institute Sleepy Hollow N.Y. Dec.   presentation San Antonio Breast Cancer Symposium Texas"