NEW YORK (AP) — Onyx Pharmaceuticals Inc. and Bayer HealthCare said Wednesday that a regimen including their cancer pill Nexavar stopped the progression of breast cancer for more than two months longer than a rival treatment. The companies said patients who took Nexavar and another cancer pill, Xeloda, lived for 6.4 months on average before their disease began to progress again. That compares with 4.1 months of progression-free survival for patients who took Xeloda and a placebo. Xeloda is made by Switzerland's Roche AG. The results were reported at an oncology conference in Berlin. Patients in the mid stage trial had advanced or metastatic breast cancer. The most serious side effects of treatment included skin reactions, diarrhea, shortness of breath, decreased white blood cell count, and inflammation of the mucous membranes in the digestive tract. The companies said in July that Nexavar met its goal in the study. The drug is currently approved to treat liver cancer and advanced kidney cancer. Onyx is based in Emeryville, Calif., and Bayer AG is based in Leverkusen, Germany.