A small study suggests that an injection into the nerves of the neck may reduce the frequency of hot flashes in women going through breast cancer treatment or menopause. Researchers used a local anesthetic to numb nerves that control temperature. The 13 women in the study reported that their hot flashes decreased significantly and in some cases went away entirely by the end of the 12-week study. Women being treated for breast cancer often have severe hot flashes, especially those taking anti-estrogen drugs.