Tom O'Brien was a horse racing enthusiast. Many in the racing industry mourn his death at the age of 39 after a cancer diagnosis. The Racing Post called him a remarkable individual. O'Brien won races at the renowned racing event. Several news outlets reported his death after a courageous battle with cancer. At Bangor, a close friend called him a hero and a skilled jockey. Yahoo News Australia said O'Brien was the another rider to die in a short span. Tributes continue across horse racing.