WOODBURY - Levitttown native Mike Cohen embarked on a 3,100-mile journey from San Diego to Long Island on his bike last month, with one purpose in mind - to thank the oncologist he credits with saving his life. Cohen, who was diagnosed with acute lymphoblastic leukemia at the age of 18, was treated by Dr. Steve Allen of the Monter Cancer Center in Lake Success. Once so weak from the treatment that he couldn't even walk down steps, Cohen celebrated his sixth year cancer-free by cycling with a friend across the country. The ride was designed to end where he finished his treatment. It was Allen's tireless effort that inspired Cohen's 38-day journey nearly a decade later, to say thank you in person to the man that saved his life. The 27-year-old now looks forward to a happy and healthy future. For the return trip to the West Coast, however, Cohen will drive.