When his doctor told him that the sharp pain in his back was stage four lung cancer, Rocky Yiu, 57, could not bring himself to ask how long he had left to live.“It felt pointless asking because they practically gave me a death sentence,” he says.Five years on, Yiu’s battle continues, aided by traditional Chinese medicine (TCM), which he believes has helped slow the spread of the disease.The number of people diagnosed with cancer in Hong Kong is increasing every year, partly due to an ageing…