是不是有皮肤癌变但不发病或能自愈？
权威资料确实如此：
http://science.education.nih.gov/supplements/nih1/cancer/activities/activity5_database2.htman estimated 2 in every 5 Americans who reach the age of 65 will develop skin cancer sometime in their lives.
40-50 percent of Americans who live to age 65 will have skin cancer at least once.
http://www.tmhs.org/tmhs/basic.do?channelId=-1073830900&contentId=1073790979&contentType=HEALTHTOPIC_CONTENT_TYPEAlmost half (40 to 50 percent) of Americans age 65 or older will have had skin cancer at least once.
中文资料也这么说：
http://ill.fh21.com.cn/zl/pfa/20061208/17564882.shtml据估计凡能活到65岁的美国白人，其中有40%～50%至少患过1次皮肤癌
但中文资料中有这个说法：
http://pdt.84468003.com/main.php?news_id=112每40－50名皮肤白皙者，在他们活到65岁时，至少有1人患皮肤癌。
该说法与“每年大约有一百万名美国人被诊断得了皮肤癌”数量级上相符。
也没见白字写学习心得，俺先提个疑问吧:)