Incidence rates increase with age form 20 years onwards reaching a peak earlier than most other cancers in the 50-59 year age group, then decrease slightly with advancing age.
从20岁以后发病率随年龄而增长，其达到峰值的时间是在50岁至59岁，比其他大多数癌症要早；然后随着年龄增长而缓慢降低。