One in three of us will be diagnosed with cancer during our lifetime. The disease tends to affect older people — but can strike at any time. Excluding certain skin cancers, there were more than 270,000 new cases of the disease in 2001 — and the rate is increasing by about 1% a year. Some cancers, such as breast, are becoming more common, while new cases of lung cancer fall away due to the drop in the number of smokers. However, while the overall number of new cancers is not falling, the good news is that successful treatment rates for many of the most common types are improving rapidly. BBC News Online, in conjunction with Cancer Research UK, has produced a guide to some of the most common forms of cancer and the treatments used to tackle them. How many people will be diagnosed with cancer during their lifetime?