(Reuters) - European shares retreated from near six-month highs on Wednesday, with German stocks leading losses as chemicals producer Bayer sank 10 percent following another U.S. court verdict on weed killer Roundup's link to cancer.With eyes on a U.S. Federal Reserve statement and news conference later in the day, and Asian markets broadly lower, the pan-European STOXX 600 index fell 0.3 percent as investors booked profits after five sessions of gains. The Fed is expected to hold interest..