Tom O'Brien was a race rider. The horse racing world mourn his death at the age of 39 after a cancer battle. Many publications called him a remarkable individual. O'Brien won races at the renowned racing event. The Guardian and 7NEWS reported his death after a courageous fight with cancer. At Bangor, a colleague called him a hero and a brilliant rider. Yahoo News Australia said O'Brien was the another rider to die in a short span. Tributes continue in the world of horse racing.